Ztorg: from rooting to SMS

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I’ve been monitoring Google Play Store for new Ztorg Trojans since September 2016, and have so far found several dozen new malicious apps. All of them were rooting malware that used exploits to gain root rights on the infected device.

Then, in the second half of May 2017 I found one that wasn’t. Distributed on Google Play through two malicious apps, it is related to the Ztorg Trojans, although not a rooting malware but a Trojan-SMS that can send Premium rate SMS and delete incoming SMS. The apps had been installed from Google Play more than 50,000 and 10,000 times respectively.

Kaspersky Lab products detect the two Trojan apps as Trojan-SMS.AndroidOS.Ztorg.a. We reported the malware to Google, and both apps have been deleted from the Google Play Store.

The first malicious app, called “Magic browser” was uploaded to Google Play on May 15, 2017 and was installed more than 50,000 times.

Ztorg: from rooting to SMS

Trojan-SMS.AndroidOS.Ztorg.a on Google Play Store

The second app, called “Noise Detector”, with the same malicious functionality, was installed more than 10,000 times.

Ztorg: from rooting to SMS

Trojan-SMS.AndroidOS.Ztorg.a on Google Play Store

What can they do?

After starting, the Trojan will wait for 10 minutes before connecting to its command and control (C&C) server. It uses an interesting technique to get commands from the C&C: it makes two GET requests to the C&C, and in both includes part of the International Mobile Subscriber Identity (IMSI). The first request will look like this:

GET c.phaishey.com/ft/x250_c.txt, where 250 – first three digits of the IMSI.

If the Trojan receives some data in return, it will make the second request. The second request will look like this:

GET c.phaishey.com/ft/x25001_0.txt, where 25001 – first five digits of the IMSI.

Why does the Trojan need these digits from the IMSI?

The interesting thing about the IMSI is that the first three digits are the MCC (mobile country code) and the third and fourth digits are the MNC (mobile network code). Using these digits, the cybercriminals can identify the country and mobile operator of the infected user. They need this to choose which premium rate SMS should be sent.

In answer to these requests, the Trojan may receive an encrypted JSON file with some data. This data should include a list of offers, and every offer carries a string field called ‘url’, which may or may not contain an actual url. The Trojan will try to open/view the field using its own class. If this value is indeed a url, the Trojan will show its content to the user. But if it is something else and carries an “SMS” substring, the user will send an SMS containing the text supplied to the number provided.

Ztorg: from rooting to SMS

Malicious code where the Trojan decides if it should send an SMS.

This is an unusual way to send SMS. Just after it receives urls to visit, or SMS to send, the Trojan will turn off the device sound, and start to delete all incoming SMS.

I wasn’t able to get any commands for the Trojans distributed through Google Play. But for other Trojans located elsewhere that have the same functionality, I got the command:

{“icon”:”http://down.rbksbtmk.com/pic/four-dault-06.jpg”,”id”:”-1″,”name”:”Brower”,”result”:1,”status”:1,”url”:”http://global.621.co/trace?offer_id=111049&aff_id=100414&type=1″}

It was a regular advertising offer.

WAP billing subscriptions

I was able to find several more malicious apps with the same functionality distributed outside the Google Play Store. The interesting thing is that they don’t look like standalone Trojans, more like an additional module for some Trojan.

Further investigation revealed that these Trojans were installed by a regular Ztorg Trojan along with other Ztorg modules.

In a few of these Trojans, I found that they download a JS file from the malicious url using the MCC.

Ztorg: from rooting to SMS

Malicious code where the Trojan downloads a JS file.

I downloaded several JS files, using different MCC’s, to find out what cybercriminals are going to do with users from a different countries. I wasn’t able to get a file for a US MCC, but for other countries that I tried I received files with some functions. All the files contain a function called “getAocPage” which most likely references AoC – Advice of Charge. After analyzing these files, I found out that their main purpose is to perform clickjacking attacks on web pages with WAP billing. In doing so, the Trojan can steal money from the user’s mobile account. WAP billing works in a similar way to Premium rate SMS, but usually in the form of subscriptions and not one-time payments as most Premium rate SMS.

Ztorg: from rooting to SMS

JS file from a CnC for Russian users (MCC = 250)

It means that urls which the Trojan receives from the CnC may not only be advertising urls, but also urls with WAP billing subscriptions. Furthermore some Trojans with this functionality use CnC urls that contain “/subscribe/api/” which may reference subscriptions too.

All of these Trojans, including Trojans from Google Play, are trying to send SMS from any device. To do so they are using lots of methods to send SMS:

Ztorg: from rooting to SMS

Part of the “Magic browser” app’s code

In total, the “Magic browser” app tries to send SMS from 11 different places in its code. Cybercriminals are doing this in order to be able to send SMS from different Android versions and devices. Furthermore, I was able to find another modification of the Trojan-SMS.AndroidOS.Ztorg that is trying to send an SMS via the “am” command, although this approach should not work.

Ztorg: from rooting to SMS

Connection with the Ztorg malware family

The “Magic browser” app was promoted in a similar way to other Ztorg Trojans. Both the Magic browser” and “Noise detector” apps shared code similarities with other Ztorg Trojans. Furthermore, the latest version of the “Noise detector” app contains the encrypted file “girl.png” in the assets folder of the installation package. After decryption, this file become a Ztorg Trojan.

I found several more Trojans with the same functionality that were installed by a regular Ztorg Trojan along with the other Ztorg modules. And it isn’t the first case where additional Ztorg modules were distributed from Google Play as a standalone Trojan. In April 2017, I found that a malicious app called “Money Converter”, had been installed more than 10,000 times from Google Play. It uses Accessibility Services to install apps from Google Play. Therefore, the Trojan can silently install and run promoted apps without any interaction with the user, even on updated devices where it cannot gain root rights.

Trojan-SMS vs. rooting

There were two malicious apps on Google Play with the same functionality – “Noise Detector” and “Magic browser” but I think that they each had a different purpose. “Magic browser” was uploaded first and I assume that the cybercriminals were checking if they were able to upload this kind of functionality. After they uploaded the malicious app they didn’t update it with newer versions.

But it is a different story with “Noise Detector” – here it looks like the cybercriminals were trying to upload an app infected with a regular version of the Ztorg Trojan. But in the process of uploading they decided to add some malicious functionality to make money while they were working on publishing the rooting malware. And the history of “Noise Detector” updates prove it.

On May 20 they uploaded a clean app called “Noise Detector”. A few days later they updated it with another clean version.

Then, a few days after that, they uploaded a version to Google Play that contained an encrypted Ztorg Trojan, but without the possibility of decrypting and executing it. On the following day they finally updated their app with the Trojan-SMS functionality, but still didn’t add the possibility to execute the encrypted Ztorg module. It is likely that, if the app hadn’t been removed from Google Play, they would have added this functionality at the next stage. There is also the possibility that attempting to add this functionality is what alerted Google to the Trojan’s presence and resulted in its deletion.

Conclusions

We found a very unusual Trojan-SMS being distributed through Google Play. It not only uses around a dozen methods to send SMS, but also initializes these methods in an unusual way: by processing web-page loading errors using a command from the CnC. And it can open advertising urls. Furthermore, it is related to Ztorg malware with the same functionality, that is often installed by Ztorg as an additional module.

By analyzing these apps I found that cybercriminals are working on clickjacking WAP billing. It means that these Trojans may not only open ad urls, or send Premium rate SMS, but also open web-pages with WAP billing and steal money from a user’s account. To hide these activities the Trojans turn off the device sound and delete all incoming SMS.

This isn’t the first time that the cybercriminals distributed Ztorg modules through Google Play. For example, on April 2017 they uploaded a module that can click on Google Play Store app buttons to install or even buy promoted apps.

Most likely, the attackers are publishing Ztorg modules to make some additional money while they are trying to upload the regular rooting Ztorg Trojan. I suggest this because one of the malicious apps had an encrypted Ztorg module but it wasn’t able to decrypt it.

MD5

  • F1EC3B4AD740B422EC33246C51E4782F
  • E448EF7470D1155B19D3CAC2E013CA0F
  • 55366B684CE62AB7954C74269868CD91
  • A44A9811DB4F7D39CAC0765A5E1621AC
  • 1142C1D53E4FBCEFC5CCD7A6F5DC7177

Honeypots and the Internet of Things

There were a number of incidents in 2016 that triggered increased interest in the security of so-called IoT or ‘smart’ devices. They included, among others, the record-breaking DDoS attacks against the French hosting provider OVH and the US DNS provider Dyn. These attacks are known to have been launched with the help of a massive botnet made up of routers, IP cameras, printers and other devices.

Last year the world also learned of a colossal botnet made up of nearly five million routers. The German telecoms giant Deutsche Telekom also encountered router hacking after the devices used by the operator’s clients became infected with Mirai. The hacking didn’t stop at network hardware: security problems were also detected in smart Miele dishwashers and AGA stoves. The ‘icing on the cake’ was the BrickerBot worm that didn’t just infect vulnerable devices like most of its ‘peers’ but actually rendered them fully inoperable.

According to Gartner, there are currently over 6 billion IoT devices on the planet. Such a huge number of potentially vulnerable gadgets could not possibly go unnoticed by cybercriminals. As of May 2017, Kaspersky Lab’s collections included several thousand different malware samples for IoT devices, about half of which were detected in 2017.

The number of IoT malware samples detected each year (2013 – 2017)

Threat to the end user

If there is an IoT device on your home network that is poorly configured or contains vulnerabilities, it could cause some serious problems. The most common scenario is your device ending up as part of a botnet. This scenario is perhaps the most innocuous for its owner; the other scenarios are more dangerous. For example, your home network devices could be used to perform illegal activities, or a cybercriminal who has gained access to an IoT device could spy on and later blackmail its owner – we have already heard of such things happening. Ultimately, the infected device can be simply broken, though this is by no means the worst thing that can happen.

The main problems of smart devices

Firmware

In the best-case scenario, device manufacturers are slow to release firmware updates for smart devices. In the worst case, firmware doesn’t get updated at all, and many devices don’t even have the ability to install firmware updates.

Software on devices may contain errors that cybercriminals can exploit. For example, the Trojan PNScan (Trojan.Linux.PNScan) attempted to hack routers by exploiting one of the following vulnerabilities:

  • CVE-2014-9727 for attacking Fritz!Box routers;
  • A vulnerability in HNAP (Home Network Administration Protocol) and the vulnerability CVE-2013-2678 for attacking Linksys routers;
  • ShellShock (CVE-2014-6271).

If any of these worked, PNScan infected the device with the Tsunami backdoor.

The Persirai Trojan exploited a vulnerability present in over 1000 different models of IP cameras. When successful, it could run arbitrary code on the device with super-user privileges.

There’s yet another security loophole related to the implementation of the TR-069 protocol. This protocol is designed for the operator to remotely manage devices, and is based on SOAP which, in turn, uses the XML format to communicate commands. A vulnerability was detected within the command parser. This infection mechanism was used in some versions of the Mirai Trojan, as well as in Hajime. This was how Deutsche Telekom devices were infected.

Passwords, telnet and SSH

Another problem is preconfigured passwords set by the manufacturer. They can be the same not just for one model but for a manufacturer’s entire product range. Furthermore, this situation has existed for so long that the login/password combinations can easily be found on the Internet – something that cybercriminals actively exploit. Another factor that makes the cybercriminal’s work easier is that many IoT devices have their telnet and/or SSH ports available to the outside world.

For instance, here is a list of login/password combinations that one version of the Gafgyt Trojan (Backdoor.Linux.Gafgyt) uses:

root root
root
telnet telnet
!root
support support
supervisor zyad1234
root antslq
root guest12345
root tini
root letacla
root Support1234

Statistics

We set up several honeypots (traps) that imitated various devices running Linux, and left them connected to the Internet to see what happened to them ‘in the wild’. The result was not long in coming: after just a few seconds we saw the first attempted connections to the open telnet port. Over a 24-hour period there were tens of thousands of attempted connections from unique IP addresses.

Number of attempted attacks on honeypots from unique IP addresses. January-April 2017.

In most cases, the attempted connections used the telnet protocol; the rest used SSH.

Distribution of attempted attacks by type of connection port used. January-April 2017

Below is a list of the most popular login/password combinations that malware programs use when attempting to connect to a telnet port:

User Password
root xc3511
root vizxv
admin admin
root admin
root xmhdipc
root 123456
root 888888
root 54321
support support
root default
root root
admin password
root anko
root
root juantech
admin smcadmin
root 1111
root 12345
root pass
admin admin1234

Here is the list used for SSH attacks. As we can see, it is slightly different.

User Password
admin default
admin admin
support support
admin 1111
admin
user user
Administrator admin
admin root
root root
root admin
ubnt ubnt
admin 12345
test test
admin <Any pass>
admin anypass
administrator
admin 1234
root password
root 123456

Now, let’s look at the types of devices from which the attacks originated. Over 63% of them could be identified as DVR services or IP cameras, while about 20% were different types of network devices and routers from all the major manufacturers. 1% were Wi-Fi repeaters and other network hardware, TV tuners, Voice over IP devices, Tor exit nodes, printers and ‘smart-home’ devices. About 20% of devices could not be identified unequivocally.

Distribution of attack sources by device type. January-April 2017

Most of the IP addresses from which attempted connections arrived at our honeypots respond to HTTP requests. Typically, there are several devices using each IP address (NAT technology is used). The device responding to the HTTP request is not always the device that attacked our honeypot, though that is usually the case.

The response to such a request was a web page – a device control panel, some form of monitoring, or maybe a video from a camera. With this returned page, it is possible to try and identify the type of device. Below is a list of the most frequent headers for the web pages returned by the attacking devices:

HTTP Title Device %
NETSurveillance WEB 17.40%
DVR Components Download 10.53%
WEB SERVICE 7.51%
main page 2.47%
IVSWeb 2.0 – Welcome 2.21%
ZXHN H208N V2.5 2.04%
Web Client 1.46%
RouterOS router configuration page 1.14%
NETSuveillance WEB 0.98%
Technicolor 0.77%
Administration Console 0.77%
MГіdem – Inicio de sesiГіn 0.67%
NEUTRON 0.58%
Open Webif 0.49%
hd client 0.48%
Login Incorrect 0.44%
iGate GW040 GPON ONT 0.44%
CPPLUS DVR – Web View 0.38%
WebCam 0.36%
GPON Home Gateway 0.34%

We only see a portion of the attacking devices at our honeypots. If we need an estimate of how many devices there are globally of the same type, dedicated search services like Shodan or ZoomEye can help out. They scan IP ranges for supported services, poll them and index the results. We took some of the most frequent headers from IP cameras, DVRs and routers, and searched for them in ZoomEye. The results were impressive: millions of devices were found that potentially could be (and most probably are) infected with malware.

Numbers of IP addresses of potentially vulnerable devices: IP cameras and DVRs.

HTTP Title Devices
WEB SERVICE 2 785 956
NETSurveillance WEB 1 621 648
dvrdvs 1 569 801
DVR Components Download 1 210 111
NetDvrV3 239 217
IVSWeb 55 382
Total 7 482 115

Numbers of IP addresses of potentially vulnerable devices: routers

HTTP Title Devices
Eltex NTP 2 653
RouterOS router 2 124 857
GPON Home Gateway 1 574 074
TL-WR841N 149 491
ZXHN H208N 79 045
TD-W8968 29 310
iGate GW040 GPON ONT 29 174
Total 3 988 604

Also noteworthy is the fact that our honeytraps not only recorded attacks coming from network hardware classed as home devices but also enterprise-class hardware.

Even more disturbing is the fact that among all the IP addresses from which attacks originated there were some that hosted monitoring and/or device management systems with enterprise and security links, such as:

  • Point-of-sale devices at stores, restaurants and filling stations
  • Digital TV broadcasting systems
  • Physical security and access control systems
  • Environmental monitoring devices
  • Monitoring at a seismic station in Bangkok
  • Industry-grade programmable microcontrollers
  • Power management systems

We cannot confirm that it is namely these types of devices that are infected. However, we have seen attacks on our honeypots arriving from the IP addresses used by these devices, which means at least one or more devices were infected on the network where they reside.

Geography of infected devices

If we look at the geographic distribution of the devices with the IP addresses that we saw attacking our honeypots, we see the following:

Breakdown of attacking device IP addresses by country. January-April 2017

As we mentioned above, most of the infected devices are IP cameras and DVRs. Many of them are widespread in China and Vietnam, as well as in Russia, Brazil, Turkey and other countries.

Geographical distribution of server IP addresses from which malware is downloaded to devices

So far in 2017, we have recorded over 2 million hacking attempts and more than 11,000 unique IP addresses from which malware for IoT devices was downloaded.

Here is the breakdown by country of these IP addresses (Top 10):

Country Unique IPs
Vietnam 2136
Taiwan, Province of China 1356
Brazil 1124
Turkey 696
Korea, Republic of 620
India 504
United States 429
Russian Federation 373
China 361
Romania 283

If we rank the countries by the number of downloads, the picture changes:

Country Downloads
Thailand 580267
Hong Kong 367524
Korea, Republic of 339648
Netherlands 271654
United States 168224
Seychelles 148322
France 68648
Honduras 36988
Italy 20272
United Kingdom 16279

We believe that this difference is due to the presence in some of these countries of bulletproof servers, meaning it’s much faster and easier to spread malware than it is to infect IoT devices.

Distribution of attack activity by days of the week

When analyzing the activities of IoT botnets, we looked at certain parameters of their operations. We found that there are certain days of the week when there are surges in malicious activity (such as scanning, password attacks, and attempted connections).

Distribution of attack activity by days of the week. April 2017

It appears Monday is a difficult day for cybercriminals too. We couldn’t find any other explanation for this peculiar behavior.

Conclusion

The growing number of malware programs targeting IoT devices and related security incidents demonstrates how serious the problem of smart device security is. 2016 has shown that these threats are not just conceptual but are in fact very real. The existing competition in the DDoS market drives cybercriminals to look for new resources to launch increasingly powerful attacks. The Mirai botnet has shown that smart devices can be harnessed for this purpose – already today, there are billions of these devices globally, and by 2020 their number will grow to 20-50 billion devices, according to predictions by analysts at different companies.

In conclusion, we offer some recommendations that may help safeguard your devices from infection:

  1. Do not allow access to your device from outside of your local network, unless you specifically need it to use your device;
  2. Disable all network services that you don’t need to use your device;
  3. If the device has a preconfigured or default password and you cannot change it, or a preconfigured account that you cannot deactivate, then disable the network services where they are used, or disable access to them from outside the local network.
  4. Before you start using your device, change the default password and set a new strong password;
  5. Regularly update your device’s firmware to the latest version (when such updates are available).

If you follow these simple recommendations, you’ll protect yourself from a large portion of existing IoT malware.

Nigerian phishing: Industrial companies under attack

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In late 2016, the Kaspersky Lab Industrial Control Systems Cyber Emergency Response Team (Kaspersky Lab ICS CERT) reported on phishing attacks that were primarily targeting industrial companies from the metallurgy, electric power, construction, engineering and other sectors. As further research demonstrated, this was just part of a bigger story that began much earlier and is unlikely to end any time soon.

Targeted Attack

In October 2016, Kaspersky Lab products detected a surge in malware infection attempts on the computers of our customers who had industrial control systems installed. The malware used in these attacks was a specific modification of an exploit for a vulnerability dating back to 2015.

Further analysis of the incident led us to phishing messages disguised as business correspondence that were used to distribute the exploit.

Phishers have long since discovered the advantages of attacking companies (they obviously have much more money in their accounts than ordinary users and they usually conduct much larger transactions than individuals). The emails used in such attacks are made to look as legitimate as possible so that the employees who receive them open the accompanying malicious attachments without giving them much thought.

In this case, we were dealing with well crafted phishing messages that targeted not only commercial organizations but, in most cases, industrial enterprises. All in all, we discovered over 500 attacked companies in more than 50 countries. Most of these companies are industrial enterprises and large transportation and logistics corporations.

The Emails

The emails were sent on behalf of various companies that did business with potential victims: suppliers, customers, commercial organizations and delivery services. The emails asked recipients to check information in an invoice as soon as possible, clarify product pricing or receive goods specified in the delivery note attached.

Nigerian Phishing

Nigerian Phishing

Nigerian Phishing

Examples of phishing emails

The phishers clearly tried hard to make their fake messages look very convincing to the employees of targeted companies. We have seen attachments with names such as “Energy & Industrial Solutions W.L.L_pdf”, “Woodeck Specifications best Prices Quote.uue” and “Saudi Aramco Quotation Request for October 2016”.

Malicious Files

All the emails had malicious attachments: RTF files with an exploit for the CVE-2015-1641 vulnerability, archives of different formats containing malicious executable files, as well as documents with macros and OLE objects designed to download malicious executable files.

In late 2016, our mail antivirus solutions detected between several hundred and several thousand emails per day containing given exploit for CVE-2015-1641.

Nigerian Phishing

Number of daily mail antivirus detections
of the exploit for CVE-2015-1641 (Exploit.MSWord.Agent.hp)

A characteristic feature of such phishing campaigns is that the number of emails sent varies depending on the day of the week: fewer emails are sent on weekends than weekdays.

The malware used in these attacks belonged to families that are popular among cybercriminals, such as ZeuS, Pony/FareIT, LokiBot, Luminosity RAT, NetWire RAT, HawkEye, ISR Stealer, and iSpy keylogger. The phishers selected a toolset that included the functionality they needed, choosing from malware available on cybercriminal forums. At the same time, the malware was packed using VB and .NET packers – a distinct feature of this campaign. To evade detection by security tools, the malicious files were regularly repacked using new modifications of the same packers.

The attackers used malware belonging to at least eight different Trojan-Spy and Backdoor families. All malicious programs selected for these attacks are designed primarily to steal confidential data and install stealthy remote administration tools on infected systems.

Domains Used by the Attackers

When we extracted C&C addresses from the detected malicious files, it turned out that in some cases the same resources were used as command-and-control servers for malware from different families. From this, it can be concluded that either there is one cybercriminal group behind these attacks, using different malware families, or different groups are cooperating closely with each other and using the same C&C to communicate to “their” malware.

The domain names of some of the malware command-and-control servers used by the attackers mimicked domain names used by industrial companies – more proof that the attacks were primarily targeting industrial companies.

An analysis of these domain names sheds light on the tactics used by the phishers. They try to register the same domain name as the targeted company’s legitimate resource, but in a different top-level domain. If this is impossible, the attackers register a domain with a name that looks very similar to the legitimate domain’s name (a standard technique is to replace one or more characters). We have also seen another technique used in these attacks: the domain name is made up of the legitimate site’s name and the name of its top-level domain.

Malware CnC Real industrial company site
hi***quil-ar.com hi***quil.com.ar
em***uae.com em***u.ae
lus***lt.com lus***lt.pt

Phishing domain names mimicking legitimate domain names

In some cases, the attackers gained unauthorized access to the legitimate websites of industrial companies and used them as a platform for hosting malware and C&C servers. The websites were accessed using credentials stolen earlier from infected computers used by the companies’ employees.

Nigerian Phishing

Compromised legitimate site

In the course of our investigation we found that, according to the publicly available information provided by Whois services, most domains used for malware C&C servers were registered to residents of Nigeria. All indications are that these were business email compromise (BEC) attacks that have come to be associated with Nigerian cybercriminals.

Attack Scenario

Business email compromise attacks are well-known. Several scenarios for these attacks have been described to date. Some of these scenarios were used in the targeted attacks we have been investigating.

Nigerian Phishing

Attack outline

In the first stage, phishers send emails with malicious attachments – Trojan-Spies or Backdoors. All malware used is available on the black market. It is worth noting that a complete set of malware for carrying out this type of attack usually costs no more than US$200.

Among other things, we have discovered messages sent using compromised email accounts of company employees, in which cybercriminals sent malicious attachments to corporate addresses at other companies.

After infecting a corporate computer, the attackers are able to make screenshots of the correspondence using malware or set up hidden redirection of messages from the attacked computer’s mailbox to their own mailbox. This enables them to track which transactions are being prepared in the company.

After selecting the most promising transaction among those in the pipeline, the attackers register domain names that are very similar to the names of the seller companies. Using the newly registered domains, the cybercriminals are able to carry out a man-in-the-middle attack: they intercept the email with the seller’s invoice and forward it to the buyer after replacing the seller’s account details with the details of an account belonging to the attackers. Alternatively, they can send a request on behalf of the seller for an urgent change of bank details in addition to the seller’s legitimate email containing the invoice.

Nigerian Phishing

Hijacking the correspondence between the seller and the buyer using a phishing email address

Another option for the cybercriminals is to send the emails on behalf of a seller with spoofed email header in such a way that it points to the seller’s legitimate mailbox as a sender. It’s worth saying that this way of sending emails is less reliable as some programs and mail servers can reveal the replacement.

In any event the chances of the recipient never suspecting anything and the criminals getting the money are very high.

Nigerian Fishing

‘Nigerian letters’ (a.k.a. 419 scams) have become classics of online fraud. The creators of fascinating stories about heiresses/widows/secretaries/lawyers of deceased millionaires/disgraced dictators/other fat cats didn’t win the Ig Nobel Prize for literature in 2005 for nothing. They may not be very highly qualified, but they certainly have a talent for extortion, and may well have been profiting from the greed and gullibility of their victims for years.

Several years ago, Nigerian phishers appeared on the radar of researchers. They were the same scammers who specialized in so-called Nigerian letters, but at the same time they were mastering new techniques for stealing money – this time, from companies. They are usually the ones behind business email compromise attacks.

There have been a good many publications on phishing attacks by Nigerian fraudsters in the past three years. This is no coincidence: this relatively new type of criminal business is gaining momentum. According to FBI estimates, the damage from Nigerian phisher activity from October 2013 to May 2016 exceeded US$3 billion and the number of affected companies was as high as 22,143. Those companies are scattered across 79 countries of the world.

In 2013-2015, mostly small and medium-size companies were attacked. The phishers gathered the email addresses of potential victims on the Internet.

Nigerian Phishing

Cybercriminals exchanging addresses for phishing email distribution. Most addresses are on publicly available email services

Since the fraudsters are interested primarily in companies that buy and sell, they use resources such as Alibaba.

Nigerian Phishing

Message with spoofed header and replaced banking details allegedly sent from Alibaba seller’s legitimate email

Phishers also buy databases of email addresses that are of interest to them. Addresses belonging to different categories of company are available on the black market. Relatively small industrial companies are among those targeted by phishers.

Nigerian Phishing

An offer to buy categorized email addresses sent to a Nigerian phisher

Clearly, targeted attacks focusing on specific regions already took place in 2015. The screenshot below shows a message that confirms the purchase of a database of UAE company addresses by a Nigerian phisher. This purchase set the cybercriminal back $99.

Nigerian Phishing

Purchase of an email address database for attacks on UAE companies by a Nigerian phisher

Some cybercriminals are prepared to pay a small fortune for email addresses:

Nigerian Phishing

Purchase of corporate data by a Nigerian phisher for $995

Hunting the Big Phish

Cybercriminals want to steal as much money as possible in one go. As a result, the companies attacked in 2016 included some major corporations.

The average value of a sales transaction can be quite high for a large company. Apparently, Nigerian hackers took note of this in 2016. We believe that a group of Nigerian phishers (or several groups working together) chose industrial and transportation companies as their main targets in 2016.

For example, Palo Alto Networks published two reports in June 2015 and February 2016 based on their analysis of phishing attacks against companies. These reports painted a familiar picture: Nigerian attackers targeted phishing emails and malware that steals confidential data – a Trojan-Spy called KeyBase was used in those attacks. Remarkably, unlike the 2015 attack, the 2016 attack targeted primarily industrial companies.

In August 2016, our colleague studied a series of phishing attacks that he dubbed Operation Ghoul. Operation Ghoul also made use of targeted phishing emails that contained malware designed to steal authentication credentials from different applications, including KeyBase. That operation in fact had much in common with the targeted attacks that we detected in the fall of 2016. In both cases, the attacks targeted mostly industrial companies and the texts of phishing emails and attached files were very similar. We also noticed fake emails sent in both campaigns on behalf of the same sender – Emirates NDB Bank. Finally, in the Operation Ghoul attacks we found files packed with a specific .NET packer (sold on hacker forums as Data Protector) that was one of the markers of the attacks we uncovered.

In the attacks analyzed by Kaspersky Lab, industrial companies account for over 80% of potential victims.

Potential Losses

Nigerian phishing attacks are particularly dangerous for industrial companies. In the event of a successful attack, the company making a purchase not only loses money but also fails to receive the goods they need on time. This can be critical for industrial companies: if the goods are raw materials used in manufacturing or spare parts needed to repair equipment, their non-delivery can result in downtime or failure to perform scheduled maintenance or commissioning and start-up work.

However, there are other possible consequences, as well. The spyware programs used by phishers send a variety of information from infected machines to their command-and-control servers.

We analyzed data from some command-and-control servers used in 2017 attacks. The amount and contents of data obtained by Nigerian phishers is truly disturbing. Cybercriminals have gained access to information on industrial companies’ operations and main assets, including information on contracts and projects.

For example, screenshots found on malware command-and-control servers included various cost estimates and project plans for some of the current projects at victim enterprises.

Nigerian Phishing Nigerian Phishing

Screenshots from infected computers

We also found screenshots that were clearly not made on the computers of project managers or procurement managers, but rather on the workstations of operators, engineers, designers and architects. They show, among other things, technical drawings, floor plans, diagrams showing the structure of electrical and information networks.

Nigerian Phishing Nigerian Phishing
Nigerian Phishing Nigerian Phishing
Nigerian Phishing

Screenshots from infected computers

Clearly, this is not needed to carry out the cybercriminals’ Nigerian scams. What do they do with this information? Do they destroy it after completing an attack? Could someone order the theft of data from a specific company?

So far, we have not seen any of the information stolen by Nigerian cybercriminals on the black market. However, it is clear that, for the companies being attacked, in addition to the direct financial loss a Nigerian phishing attack poses other, possibly more serious, threats.

This malicious phishing campaign is ongoing and is unlikely to cease in the foreseeable future.

Nigerian Phishing

Phishing attacks agains industrial companies continue

Nigerian phishing is clearly a profitable type of cybercrime that does not require significant financial investment or a high level of technical knowledge. It appears that Nigerian threat actors don’t face stiff competition, at least for now: they readily share information as well as command-and-control servers used by malware. However, as in the case of Nigerian letter scams, this type of cybercriminal activity, can easily be adopted by other criminals. That is if they haven’t already done so, of course.

P.S. The Hidden Threat

And last – though by no means least – it is very dangerous if as a result of an infection cybercriminals gain access to computers that are part of an industrial control system (ICS). In such cases, they can gain remote access to the ICS and unauthorized control over industrial processes.

Remote access to SCADA machines enables attackers to simply switch industrial equipment off or change its settings. There are known cases of hackers changing the parameters of an industrial process without any obvious malicious intent – simply out of curiosity. In 2016, Verizon published data breach digest describes several attacks investigated by the company, including one aimed at the systems of an unnamed US water utility. In the course of the attack, the cybercriminals managed to infiltrate the control system and change the amounts of chemicals used to treat tap water and the flow rate. At the same time, according to Verizon experts, the hackers didn’t understand what the results of the changes they were making would be and changed the settings randomly. In this context, it has to be hoped that the interests of Nigerian phishers will be limited to stealing money and that they won’t tamper with ICS controls.

Unfortunately, there is no guarantee that people who want to carry out acts of sabotage will not gain access to computers in industrial enterprises, including SCADA systems.

Protection Measures

The following measures are needed to mitigate attacks which involve social engineering techniques:

  • Regularly brief employees on security rules when working with email and the Internet. Train employees in the basic rules of cyber-hygiene, such as not opening suspicious links and attachments, carefully checking sender and recipient addresses, company names and the actual domain names from which messages were sent.
  • Inform employees not only about the tools that can be used by cybercriminals, but also about the fraudulent schemes they use.
  • In the course of conducting a transaction, if an unexpected request is received from the seller to change the bank details, payment methods or other parameters of the transaction, it is best to contact the seller by phone or using other methods unrelated to email and ask for confirmation of the changes.

The following protection measures are recommended to minimize the risk of infection and any damage from attacks:

  • Install a security solution on all workstations and servers where possible.
  • Keep security software, signature databases, heuristic and decision rule databases up to date.
  • Where possible, install operating system and software updates without delay.
  • In the event of a system being compromised, change the passwords for all accounts used on that system.
  • Promptly send suspicious emails, attachments and domain names for analysis to highly qualified experts, such as Kaspersky Lab ICS CERT experts.

On industrial information systems, whose composition and configuration cannot be changed quickly, the greatest effect can be achieved by using application startup control and device control technologies in whitelisting mode in combination with application behavior control technologies and protection against network attacks. We also recommend the following measures:

  • Install tools that provide passive monitoring of network activity on the industrial network, capable of detecting newly connected devices, suspicious network connections, and malware network communication. These tools will help to detect and monitor attempts by threat actors to penetrate the enterprise’s network. Importantly, some of these tools are very easy to install and do not require the composition or configuration of the industrial control systems to be changed in any way.
  • Install tools that provide deep analysis of network traffic on the industrial network and detection of commands that can potentially disrupt the industrial process. Using this class of system is absolutely necessary for the detection and timely prevention of advanced attacks designed to physically damage an enterprise’s systems and carried out by highly qualified external or internal threat actors. This type of technology can also be implemented passively, without any impact on the operation of industrial control systems.
  • Minimize the range and quantity of software products used in ICS segments.
  • Restrict the use of computers that are part of an ICS for purposes unrelated to the industrial processes. These measures can be implemented using application startup control tools included in endpoint security solutions.

High-quality and properly configured security solutions help to protect an enterprise against the vast majority of chance infections and many targeted attacks, especially those carried out using tools that are not particularly sophisticated.

TA17-164A: HIDDEN COBRA – North Korea’s DDoS Botnet Infrastructure

Original release date: June 13, 2017

Systems Affected

Networked Systems

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). This alert provides technical details on the tools and infrastructure used by cyber actors of the North Korean government to target the media, aerospace, financial, and critical infrastructure sectors in the United States and globally. Working with U.S. Government partners, DHS and FBI identified Internet Protocol (IP) addresses associated with a malware variant, known as DeltaCharlie, used to manage North Korea’s distributed denial-of-service (DDoS) botnet infrastructure. This alert contains indicators of compromise (IOCs), malware descriptions, network signatures, and host-based rules to help network defenders detect activity conducted by the North Korean government. The U.S. Government refers to the malicious cyber activity by the North Korean government as HIDDEN COBRA.

If users or administrators detect the custom tools indicative of HIDDEN COBRA, these tools should be immediately flagged, reported to the DHS National Cybersecurity Communications and Integration Center (NCCIC) or the FBI Cyber Watch (CyWatch), and given highest priority for enhanced mitigation. This alert identifies IP addresses linked to systems infected with DeltaCharlie malware and provides descriptions of the malware and associated malware signatures. DHS and FBI are distributing these IP addresses to enable network defense activities and reduce exposure to the DDoS command-and-control network. FBI has high confidence that HIDDEN COBRA actors are using the IP addresses for further network exploitation.

This alert includes technical indicators related to specific North Korean government cyber operations and provides suggested response actions to those indicators, recommended mitigation techniques, and information on reporting incidents to the U.S. Government.

For a downloadable copy of IOCs, see:

Description

Since 2009, HIDDEN COBRA actors have leveraged their capabilities to target and compromise a range of victims; some intrusions have resulted in the exfiltration of data while others have been disruptive in nature. Commercial reporting has referred to this activity as Lazarus Group[1] and Guardians of Peace.[2] DHS and FBI assess that HIDDEN COBRA actors will continue to use cyber operations to advance their government’s military and strategic objectives. Cyber analysts are encouraged to review the information provided in this alert to detect signs of malicious network activity.

Tools and capabilities used by HIDDEN COBRA actors include DDoS botnets, keyloggers, remote access tools (RATs), and wiper malware. Variants of malware and tools used by HIDDEN COBRA actors include Destover,[3] Wild Positron/Duuzer,[4] and Hangman.[5] DHS has previously released Alert TA14-353A,[6] which contains additional details on the use of a server message block (SMB) worm tool employed by these actors. Further research is needed to understand the full breadth of this group’s cyber capabilities. In particular, DHS recommends that more research should be conducted on the North Korean cyber activity that has been reported by cybersecurity and threat research firms.

HIDDEN COBRA actors commonly target systems running older, unsupported versions of Microsoft operating systems. The multiple vulnerabilities in these older systems provide cyber actors many targets for exploitation. These actors have also used Adobe Flash player vulnerabilities to gain initial entry into users’ environments.

HIDDEN COBRA is known to use vulnerabilities affecting various applications. These vulnerabilities include:

  • CVE-2015-6585: Hangul Word Processor Vulnerability
  • CVE-2015-8651: Adobe Flash Player 18.0.0.324 and 19.x Vulnerability
  • CVE-2016-0034: Microsoft Silverlight 5.1.41212.0 Vulnerability
  • CVE-2016-1019: Adobe Flash Player 21.0.0.197 Vulnerability
  • CVE-2016-4117: Adobe Flash Player 21.0.0.226 Vulnerability

We recommend that organizations upgrade these applications to the latest version and patch level. If Adobe Flash or Microsoft Silverlight is no longer required, we recommend that those applications be removed from systems.

The indicators provided with this alert include IP addresses determined to be part of the HIDDEN COBRA botnet infrastructure, identified as DeltaCharlie. The DeltaCharlie DDoS bot was originally reported by Novetta in their 2016 Operation Blockbuster Malware Report. This malware has used the IP addresses identified in the accompanying .csv and .stix files as both source and destination IPs. In some instances, the malware may have been present on victims’ networks for a significant period.

Technical Details

DeltaCharlie is a DDoS tool used by HIDDEN COBRA actors, and is referenced and detailed in Novetta’s Operation Blockbuster Destructive Malware report. The information related to DeltaCharlie from the Operation Blockbuster Destructive Malware report should be viewed in conjunction with the IP addresses listed in the .csv and .stix files provided within this alert. DeltaCharlie is a DDoS tool capable of launching Domain Name System (DNS) attacks, Network Time Protocol (NTP) attacks, and Character Generation Protocol attacks. The malware operates on victims’ systems as a svchost-based service and is capable of downloading executables, changing its own configuration, updating its own binaries, terminating its own processes, and activating and terminating denial-of-service attacks. Further details on the malware can be found in Novetta’s report available at the following URL:

https://www.operationblockbuster.com/wp-content/uploads/2016/02/Operation-Blockbuster-Destructive-Malware-Report.pdf

Detection and Response

HIDDEN COBRA IOCs related to DeltaCharlie are provided within the accompanying .csv and .stix files of this alert. DHS and FBI recommend that network administrators review the IP addresses, file hashes, network signatures, and YARA rules provided, and add the IPs to their watchlist to determine whether malicious activity has been observed within their organization.

When reviewing network perimeter logs for the IP addresses, organizations may find numerous instances of these IP addresses attempting to connect to their systems. Upon reviewing the traffic from these IP addresses, system owners may find that some traffic corresponds to malicious activity and some to legitimate activity. System owners are also advised to run the YARA tool on any system they suspect to have been targeted by HIDDEN COBRA actors. Additionally, the appendices of this report provide network signatures to aid in the detection and mitigation of HIDDEN COBRA activity.

Network Signatures and Host-Based Rules

This section contains network signatures and host-based rules that can be used to detect malicious activity associated with HIDDEN COBRA actors. Although created using a comprehensive vetting process, the possibility of false positives always remains. These signatures and rules should be used to supplement analysis and should not be used as a sole source of attributing this activity to HIDDEN COBRA actors.

Network Signatures

alert tcp any any -> any any (msg:”DPRK_HIDDEN_COBRA_DDoS_HANDSHAKE_SUCCESS”; dsize:6; flow:established,to_server; content:”|18 17 e9 e9 e9 e9|”; fast_pattern:only; sid:1; rev:1;)

________________________________________________________________

alert tcp any any -> any any (msg:”DPRK_HIDDEN_COBRA_Botnet_C2_Host_Beacon”; flow:established,to_server; content:”|1b 17 e9 e9 e9 e9|”; depth:6; fast_pattern; sid:1; rev:1;)

________________________________________________________________

YARA Rules

“strings:

$rsaKey = {7B 4E 1E A7 E9 3F 36 4C DE F4 F0 99 C4 D9 B7 94

A1 FF F2 97 D3 91 13 9D C0 12 02 E4 4C BB 6C 77

48 EE 6F 4B 9B 53 60 98 45 A5 28 65 8A 0B F8 39

73 D7 1A 44 13 B3 6A BB 61 44 AF 31 47 E7 87 C2

AE 7A A7 2C 3A D9 5C 2E 42 1A A6 78 FE 2C AD ED

39 3F FA D0 AD 3D D9 C5 3D 28 EF 3D 67 B1 E0 68

3F 58 A0 19 27 CC 27 C9 E8 D8 1E 7E EE 91 DD 13

B3 47 EF 57 1A CA FF 9A 60 E0 64 08 AA E2 92 D0}

condition: any of them”

________________________________________________________________

“strings:

$STR1 = “Wating” wide ascii

$STR2 = “Reamin” wide ascii

$STR3 = “laptos” wide ascii

condition: (uint16(0) == 0x5A4D or uint16(0) == 0xCFD0 or uint16(0) == 0xC3D4 or uint32(0) == 0x46445025 or uint32(1) == 0x6674725C) and 2 of them}”

________________________________________________________________

“strings:

$randomUrlBuilder = { 83 EC 48 53 55 56 57 8B 3D ?? ?? ?? ?? 33 C0 C7 44 24 28 B4 6F 41 00 C7 44 24 2C B0 6F 41 00 C7 44 24 30 AC 6F 41 00 C7 44 24 34 A8 6F 41 00 C7 44 24 38 A4 6F 41 00 C7 44 24 3C A0 6F 41 00 C7 44 24 40 9C 6F 41 00 C7 44 24 44 94 6F 41 00 C7 44 24 48 8C 6F 41 00 C7 44 24 4C 88 6F 41 00 C7 44 24 50 80 6F 41 00 89 44 24 54 C7 44 24 10 7C 6F 41 00 C7 44 24 14 78 6F 41 00 C7 44 24 18 74 6F 41 00 C7 44 24 1C 70 6F 41 00 C7 44 24 20 6C 6F 41 00 89 44 24 24 FF D7 99 B9 0B 00 00 00 F7 F9 8B 74 94 28 BA 9C 6F 41 00 66 8B 06 66 3B 02 74 34 8B FE 83 C9 FF 33 C0 8B 54 24 60 F2 AE 8B 6C 24 5C A1 ?? ?? ?? ?? F7 D1 49 89 45 00 8B FE 33 C0 8D 5C 11 05 83 C9 FF 03 DD F2 AE F7 D1 49 8B FE 8B D1 EB 78 FF D7 99 B9 05 00 00 00 8B 6C 24 5C F7 F9 83 C9 FF 33 C0 8B 74 94 10 8B 54 24 60 8B FE F2 AE F7 D1 49 BF 60 6F 41 00 8B D9 83 C9 FF F2 AE F7 D1 8B C2 49 03 C3 8B FE 8D 5C 01 05 8B 0D ?? ?? ?? ?? 89 4D 00 83 C9 FF 33 C0 03 DD F2 AE F7 D1 49 8D 7C 2A 05 8B D1 C1 E9 02 F3 A5 8B CA 83 E1 03 F3 A4 BF 60 6F 41 00 83 C9 FF F2 AE F7 D1 49 BE 60 6F 41 00 8B D1 8B FE 83 C9 FF 33 C0 F2 AE F7 D1 49 8B FB 2B F9 8B CA 8B C1 C1 E9 02 F3 A5 8B C8 83 E1 03 F3 A4 8B 7C 24 60 8D 75 04 57 56 E8 ?? ?? ?? ?? 83 C4 08 C6 04 3E 2E 8B C5 C6 03 00 5F 5E 5D 5B 83 C4 48 C3 }

condition: $randomUrlBuilder”

________________________________________________________________

 

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.

Solution

Mitigation Strategies

Network administrators are encouraged to apply the following recommendations, which can prevent as many as 85 percent of targeted cyber intrusions. The mitigation strategies provided may seem like common sense. However, many organizations fail to use these basic security measures, leaving their systems open to compromise:

  1. Patch applications and operating systems – Most attackers target vulnerable applications and operating systems. Ensuring that applications and operating systems are patched with the latest updates greatly reduces the number of exploitable entry points available to an attacker. Use best practices when updating software and patches by only downloading updates from authenticated vendor sites.
  2. Use application whitelisting – Whitelisting is one of the best security strategies because it allows only specified programs to run while blocking all others, including malicious software.
  3. Restrict administrative privileges – Threat actors are increasingly focused on gaining control of legitimate credentials, especially credentials associated with highly privileged accounts. Reduce privileges to only those needed for a user’s duties. Separate administrators into privilege tiers with limited access to other tiers.
  4. Segment networks and segregate them into security zones – Segment networks into logical enclaves and restrict host-to-host communications paths. This helps protect sensitive information and critical services, and limits damage from network perimeter breaches.
  5. Validate input – Input validation is a method of sanitizing untrusted input provided by users of a web application. Implementing input validation can protect against the security flaws of web applications by significantly reducing the probability of successful exploitation. Types of attacks possibly averted include Structured Query Language (SQL) injection, cross-site scripting, and command injection.
  6. Use stringent file reputation settings – Tune the file reputation systems of your anti-virus software to the most aggressive setting possible. Some anti-virus products can limit execution to only the highest reputation files, stopping a wide range of untrustworthy code from gaining control.
  7. Understand firewalls – Firewalls provide security to make your network less susceptible to attack. They can be configured to block data and applications from certain locations (IP whitelisting), while allowing relevant and necessary data through.

Response to Unauthorized Network Access

Enforce your security incident response and business continuity plan. It may take time for your organization’s IT professionals to isolate and remove threats to your systems and restore normal operations. Meanwhile, you should take steps to maintain your organization’s essential functions according to your business continuity plan. Organizations should maintain and regularly test backup plans, disaster recovery plans, and business continuity procedures.

Contact DHS or your local FBI office immediately. To report an intrusion and request resources for incident response or technical assistant, you are encouraged to contact DHS NCCIC ([email protected] or 888-282-0870), the FBI through a local field office, or the FBI’s Cyber Division ([email protected] or 855-292-3937).

Protect Against SQL Injection and Other Attacks on Web Services

To protect against code injections and other attacks, system operators should routinely evaluate known and published vulnerabilities, periodically perform software updates and technology refreshes, and audit external-facing systems for known web application vulnerabilities. They should also take the following steps to harden both web applications and the servers hosting them to reduce the risk of network intrusion via this vector.

  • Use and configure available firewalls to block attacks.
  • Take steps to secure Windows systems, such as installing and configuring Microsoft’s Enhanced Mitigation Experience Toolkit (EMET) and Microsoft AppLocker.
  • Monitor and remove any unauthorized code present in any www directories.
  • Disable, discontinue, or disallow the use of Internet Control Message Protocol (ICMP) and Simple Network Management Protocol (SNMP) as much as possible.
  • Remove unnecessary HTTP verbs from web servers. Typical web servers and applications only require GET, POST, and HEAD.
  • Where possible, minimize server fingerprinting by configuring web servers to avoid responding with banners identifying the server software and version number.
  • Secure both the operating system and the application.
  • Update and patch production servers regularly.
  • Disable potentially harmful SQL-stored procedure calls.
  • Sanitize and validate input to ensure that it is properly typed and does not contain escaped code.
  • Consider using type-safe stored procedures and prepared statements.
  • Audit transaction logs regularly for suspicious activity.
  • Perform penetration testing on web services.
  • Ensure error messages are generic and do not expose too much information.

Permissions, Privileges, and Access Controls

System operators should take the following steps to limit permissions, privileges, and access controls.

  • Reduce privileges to only those needed for a user’s duties.
  • Restrict users’ ability (permissions) to install and run unwanted software applications, and apply the principle of “Least Privilege” to all systems and services. Restricting these privileges may prevent malware from running or limit its capability to spread through the network.
  • Carefully consider the risks before granting administrative rights to users on their own machines.
  • Scrub and verify all administrator accounts regularly.
  • Configure Group Policy to restrict all users to only one login session, where possible.
  • Enforce secure network authentication, where possible.
  • Instruct administrators to use non-privileged accounts for standard functions such as web browsing or checking webmail.
  • Segment networks into logical enclaves and restrict host-to-host communication paths. Containment provided by enclaving also makes incident cleanup significantly less costly.
  • Configure firewalls to disallow Remote Desktop Protocol (RDP) traffic coming from outside of the network boundary, except for in specific configurations such as when tunneled through a secondary virtual private network (VPN) with lower privileges.
  • Audit existing firewall rules and close all ports that are not explicitly needed for business. Specifically, carefully consider which ports should be connecting outbound versus inbound.
  • Enforce a strict lockout policy for network users and closely monitor logs for failed login activity. Failed login activity can be indicative of failed intrusion activity.
  • If remote access between zones is an unavoidable business need, log and monitor these connections closely.
  • In environments with a high risk of interception or intrusion, organizations should consider supplementing password authentication with other forms of authentication such as challenge/response or multifactor authentication using biometric or physical tokens.

Logging Practices

System operators should follow these secure logging practices.

  • Ensure event logging, including applications, events, login activities, and security attributes, is turned on or monitored for identification of security issues.
  • Configure network logs to provide adequate information to assist in quickly developing an accurate determination of a security incident.
  • Upgrade PowerShell to new versions with enhanced logging features and monitor the logs to detect usage of PowerShell commands, which are often malware-related.
  • Secure logs in a centralized location and protect them from modification.
  • Prepare an incident response plan that can be rapidly administered in case of a cyber intrusion.

 

References

Revision History

  • June 13, 2017: Initial Release

This product is provided subject to this Notification and this Privacy & Use policy.

TA17-163A: CrashOverride Malware

Original release date: June 12, 2017

Systems Affected

Industrial Controls Systems

Overview

The National Cybersecurity and Communications Integration Center (NCCIC) is aware of public reports from ESET and Dragos outlining a new, highly capable Industrial Controls Systems (ICS) attack platform that was reportedly used in 2016 against critical infrastructure in Ukraine. As reported by ESET and Dragos, the CrashOverride malware is an extensible platform that could be used to target critical infrastructure sectors. NCCIC is working with its partners to validate the ESET and Dragos analysis, and develop a better understanding of the risk this new malware poses to the U.S. critical infrastructure.

Although this activity is still under investigation, NCCIC is sharing this report to provide organizations with detection and mitigation recommendations to help prevent future compromises within their critical infrastructure networks. NCCIC continues to work with interagency and international partners on this activity and will provide updates as information becomes available.

For a downloadable copy of listings of IOCs, see:

To report activity related to this Incident Report Alert, please contact NCCIC at [email protected] or 1-888-282-0870.

Risk Evaluation

NCCIC Cyber Incident Scoring System (NCISS) Rating Priority Level (Color)
Yellow (Medium)
A medium priority incident may affect public health or safety, national security, economic security, foreign relations, civil liberties, or public confidence.

Details

There is no evidence to suggest this malware has affected U.S. critical infrastructure; however, the tactics, techniques, and procedures (TTPs) described as part of the CrashOverride malware could be modified to target U.S. critical information networks and systems.

Description

Technical Analysis

CrashOverride malware represents a scalable, capable platform. The modules and capabilities publically reported appear to focus on organizations using ICS protocols IEC101, IEC104, and IEC61850, which are more commonly used outside the United States in electric power control systems. The platform fundamentally abuses a targeted ICS system’s legitimate control systems functionality to achieve its intended effect. While the known capabilities do not appear to be U.S.-focused, it is more important to recognized that the general TTPs used in CrashOverride could be leveraged with modified technical implementations to affect U.S.-based critical infrastructure. With further modification, CrashOverride or similar malware could have implications beyond electric power so all critical infrastructure organizations should be evaluating their systems to susceptibilities in the TTPs outlined. The malware has several reported capabilities:

  1. Issues valid commands directly to remote terminal units (RTUs) over ICS protocols. As reported by Dragos, one such command sequence toggles circuit breakers in a rapid open-close-open-close pattern. This could create conditions where individual utilities may island from infected parties, potentially resulting in a degradation of grid reliability.
  2. Denies service to local serial COM ports on windows devices, therefore preventing legitimate communications with field equipment over serial from the affected device.
  3. Scans and maps ICS environment using a variety of protocols, including Open Platform Communications (OPC). This significantly improves the payload’s probability of success.
  4. Could exploit Siemens relay denial-of-service (DoS) vulnerability, leading to a shutdown of the relay. In this instance, the relay would need to be manually reset to restore functionality.
  5. Includes a wiper module in the platform that renders windows systems inert, requiring a rebuild or backup restoration.

Detection

As CrashOverride is a second stage malware capability and has the ability to operate independent of initial C2, traditional methods of detection may not be sufficient to detect infections prior to the malware executing. As a result, organizations are encouraged to implement behavioral analysis techniques to attempt to identify pre-courser activity to CrashOverride. As additional information becomes available on stage one infection vectors and TTPs, this alert will be updated.

NCCIC is providing a compilation of indicators of compromise (IOCs) from a variety of sources to aid in the detection of this malware in the appendices. The sources provided do not constitute an exhaustive list and the U.S. Government does not endorse or support any particular product or vendor’s information referenced in this report. However, NCCIC has included this data to ensure wide distribution of the most comprehensive information available and will provide updates as warranted.

Signatures

import “pe”
import “hash”

rule dragos_crashoverride_exporting_dlls
{
meta:
description = “CRASHOVERRIDE v1 Suspicious Export”
author = “Dragos Inc”
condition:
pe.exports(“Crash”) & pe.characteristics
}

rule dragos_crashoverride_suspcious
{
meta:
description = “CRASHOVERRIDE v1 Wiper”
author = “Dragos Inc”
strings:
$s0 = “SYS_BASCON.COM” fullword nocase wide
$s1 = “.pcmp” fullword nocase wide
$s2 = “.pcmi” fullword nocase wide
$s3 = “.pcmt” fullword nocase wide
$s4 = “.cin” fullword nocase wide
condition:
pe.exports(“Crash”) and any of ($s*)
}

rule dragos_crashoverride_name_search {
meta:
description = “CRASHOVERRIDE v1 Suspicious Strings and Export”
author = “Dragos Inc”
strings:
$s0 = “101.dll” fullword nocase wide
$s1 = “Crash101.dll” fullword nocase wide
$s2 = “104.dll” fullword nocase wide
$s3 = “Crash104.dll” fullword nocase wide
$s4 = “61850.dll” fullword nocase wide
$s5 = “Crash61850.dll” fullword nocase wide
$s6 = “OPCClientDemo.dll” fullword nocase wide
$s7 = “OPC” fullword nocase wide
$s8 = “CrashOPCClientDemo.dll” fullword nocase wide
$s9 = “D2MultiCommService.exe” fullword nocase wide
$s10 = “CrashD2MultiCommService.exe” fullword nocase wide
$s11 = “61850.exe” fullword nocase wide
$s12 = “OPC.exe” fullword nocase wide
$s13 = “haslo.exe” fullword nocase wide
$s14 = “haslo.dat” fullword nocase wide
condition:
any of ($s*) and pe.exports(“Crash”)
}

rule dragos_crashoverride_hashes {
meta:
description = “CRASHOVERRIDE Malware Hashes”
author = “Dragos Inc”

condition:
filesize < 1MB and
hash.sha1(0, filesize) == “f6c21f8189ced6ae150f9ef2e82a3a57843b587d” or
hash.sha1(0, filesize) == “cccce62996d578b984984426a024d9b250237533” or
hash.sha1(0, filesize) == “8e39eca1e48240c01ee570631ae8f0c9a9637187” or
hash.sha1(0, filesize) == “2cb8230281b86fa944d3043ae906016c8b5984d9” or
hash.sha1(0, filesize) == “79ca89711cdaedb16b0ccccfdcfbd6aa7e57120a” or
hash.sha1(0, filesize) == “94488f214b165512d2fc0438a581f5c9e3bd4d4c” or
hash.sha1(0, filesize) == “5a5fafbc3fec8d36fd57b075ebf34119ba3bff04” or
hash.sha1(0, filesize) == “b92149f046f00bb69de329b8457d32c24726ee00” or
hash.sha1(0, filesize) == “b335163e6eb854df5e08e85026b2c3518891eda8”
}

rule dragos_crashoverride_moduleStrings {
meta:
description = “IEC-104 Interaction Module Program Strings”
author = “Dragos Inc”
strings:
$s1 = “IEC-104 client: ip=%s; port=%s; ASDU=%u” nocase wide ascii
$s2 = “ MSTR ->> SLV” nocase wide ascii
$s3 = “ MSTR <<- SLV” nocase wide ascii
$s4 = “Unknown APDU format !!!” nocase wide ascii
$s5 = “iec104.log” nocase wide ascii
condition:
any of ($s*)
}

rule dragos_crashoverride_configReader
{
meta:
description = “CRASHOVERRIDE v1 Config File Parsing”
author = “Dragos Inc”
strings:
$s0 = { 68 e8 ?? ?? ?? 6a 00 e8 a3 ?? ?? ?? 8b f8 83 c4 ?8 }
$s1 = { 8a 10 3a 11 75 ?? 84 d2 74 12 }
$s2 = { 33 c0 eb ?? 1b c0 83 c8 ?? }
$s3 = { 85 c0 75 ?? 8d 95 ?? ?? ?? ?? 8b cf ?? ?? }
condition:
all of them
}

rule dragos_crashoverride_configReader
{
meta:
description = “CRASHOVERRIDE v1 Config File Parsing”
author = “Dragos Inc”
strings:
$s0 = { 68 e8 ?? ?? ?? 6a 00 e8 a3 ?? ?? ?? 8b f8 83 c4 ?8 }
$s1 = { 8a 10 3a 11 75 ?? 84 d2 74 12 }
$s2 = { 33 c0 eb ?? 1b c0 83 c8 ?? }
$s3 = { 85 c0 75 ?? 8d 95 ?? ?? ?? ?? 8b cf ?? ?? }
condition:
all of them
}

rule dragos_crashoverride_weirdMutex
{
meta:
description = “Blank mutex creation assoicated with CRASHOVERRIDE”
author = “Dragos Inc”
strings:
$s1 = { 81 ec 08 02 00 00 57 33 ff 57 57 57 ff 15 ?? ?? 40 00 a3 ?? ?? ?? 00 85 c0 }
$s2 = { 8d 85 ?? ?? ?? ff 50 57 57 6a 2e 57 ff 15 ?? ?? ?? 00 68 ?? ?? 40 00}
condition:
all of them
}

rule dragos_crashoverride_serviceStomper
{
meta:
description = “Identify service hollowing and persistence setting”
author = “Dragos Inc”
strings:
$s0 = { 33 c9 51 51 51 51 51 51 ?? ?? ?? }
$s1 = { 6a ff 6a ff 6a ff 50 ff 15 24 ?? 40 00 ff ?? ?? ff 15 20 ?? 40 00 }
condition:
all of them
}

rule dragos_crashoverride_wiperModuleRegistry
{
meta:
description = “Registry Wiper functionality assoicated with CRASHOVERRIDE”
author = “Dragos Inc”
strings:
$s0 = { 8d 85 a0 ?? ?? ?? 46 50 8d 85 a0 ?? ?? ?? 68 68 0d ?? ?? 50 }
$s1 = { 6a 02 68 78 0b ?? ?? 6a 02 50 68 b4 0d ?? ?? ff b5 98 ?? ?? ?? ff 15 04 ?? ?? ?? }
$s2 = { 68 00 02 00 00 8d 85 a0 ?? ?? ?? 50 56 ff b5 9c ?? ?? ?? ff 15 00 ?? ?? ?? 85 c0 }
condition:
all of them
}

rule dragos_crashoverride_wiperFileManipulation
{
meta:
description = “File manipulation actions associated with CRASHOVERRIDE wip¬er”
author = “Dragos Inc”
strings:
$s0 = { 6a 00 68 80 00 00 00 6a 03 6a 00 6a 02 8b f9 68 00 00 00 40 57 ff 15 1c ?? ?? ?? 8b d8 }
$s2 = { 6a 00 50 57 56 53 ff 15 4c ?? ?? ?? 56 }
condition:
all of them
}

Impact

A successful network intrusion can have severe impacts, particularly if the compromise becomes public and sensitive information is exposed. Possible impacts include:

  • temporary or permanent loss of sensitive or proprietary information,
  • disruption to regular operations,
  • financial losses incurred to restore systems and files, and
  • potential harm to an organization’s reputation.
     

Solution

Properly implemented defensive techniques and common cyber hygiene practices increase the complexity of barriers that adversaries must overcome to gain unauthorized access to critical information networks and systems. In addition, malicious network activity should trigger detection and prevention mechanisms that enable organizations to contain and respond to intrusions more rapidly. There is no set of defensive techniques or programs that will completely avert all attacks however, layered cybersecurity defenses will aid in reducing an organization’s attack surface and will increase the likelihood of detection. This layered mitigation approach is known as defense-in-depth.
NCCIC has based its mitigations and recommendations on its analysis of the public reporting of this malware and will be provide updates as more information becomes available.
Critical infrastructure companies should to ensure that they are following best practices, which are detailed in such as those outlined in the Seven Steps to Effectively Defend Industrial Control Systems document produced jointly by DHS, NSA, and FBI.

Application Whitelisting

Application whitelisting (AWL) can detect and prevent attempted execution of malware uploaded by adversaries. Application whitelisting hardens operating systems and prevents the execution of unauthorized software. The static nature of some systems, such as database servers and human-machine interface (HMI) computers make these ideal candidates to run AWL. NCCIC encourages operators to work with their vendors to baseline and calibrate AWL deployments.
Operators may choose to implement directory whitelisting rather than trying to list every possible permutation of applications in an environment. Operators may implement application or application directory whitelisting through Microsoft Software Restriction Policy (SRP), AppLocker, or similar application whitelisting software. Safe defaults allow applications to run from PROGRAMFILES, PROGRAMFILES(X86), SYSTEM32, and any ICS software folders. All other locations should be disallowed unless an exception is granted.

Manage Authentication and Authorization

This malware exploits the lack of authentication and authorization in common ICS protocols to issue unauthorized commands to field devices. Asset owners/operators should implement authentication and authorization protocols to ensure field devices verify the authenticity of commands before they are actioned. In some instances, legacy hardware may not be capable of implementing these protections. In these cases, asset owners can either leverage ICS firewalls to do stateful inspection and authentication of commands, or upgrade their control field devices.

Adversaries are increasingly focused on gaining control of legitimate credentials, especially those associated with highly privileged accounts. Compromising these credentials allows adversaries to masquerade as legitimate users, leaving less evidence of compromise than more traditional attack options (i.e., exploiting vulnerabilities or uploading malware). For this reason, operators should implement multi-factor authentication where possible and reduce privileges to only those needed for a user’s duties. If passwords are necessary, operators should implement secure password policies, stressing length over complexity. For all accounts, including system and non-interactive accounts, operators should ensure credentials are unique, and changed, at a minimum, every 90 days.

NCCIC also recommends that operators require separate credentials for corporate and control network zones and store them in separate trust stores. Operators should never share Active Directory, RSA ACE servers, or other trust stores between corporate and control networks. Specifically, operators should:

  • Decrease a threat actor’s ability to access key network resources by implementing the principle of least privilege;
  • Limit the ability of a local administrator account to login from a local interactive session (e.g., “Deny access to this computer from the network”) and prevent access via a remote desktop protocol session;
  • Remove unnecessary accounts, groups, and restrict root access;
  • Control and limit local administration; and
  • Make use of the Protected Users Active Directory group in Windows Domains to further secure privileged user accounts against pass-the-hash attacks.

Handling Destructive Malware

Destructive malware continues to be a threat to both critical infrastructure and business systems. NCCIC encourages organizations to review the ICS-CERT destructive malware white paper for detailed mitigation guidance. It is important for organizations to maintain backups of key data, systems, and configurations such as:

  • Server gold images;
  • ICS Workstation gold configurations;
  • Engineering workstation images;
  • PLC/RTU configurations;
  • Passwords and configuration information; and
  • Offline copies of install media for operating systems and control applications.

Ensure Proper Configuration/Patch Management

Adversaries often target unpatched systems. A configuration/patch management program centered on the safe importation and implementation of trusted patches will help render control systems more secure.

Such a program will start with an accurate baseline and asset inventory to track what patches are needed. The program will prioritize patching and configuration management of “PC-architecture” machines used in HMI, database server, and engineering workstation roles, as current adversaries have significant cyber capabilities against these systems. Infected laptops are a significant malware vector. Such a program will limit the connection of external laptops to the control network and ideally supply vendors with known-good company laptops. The program will also encourage initial installation of any updates onto a test system that includes malware detection features before the updates are installed on operational systems.

NCCIC recommends operators to:

  • Use best practices when downloading software and patches destined for their control network;
  • Take measures to avoid watering hole attacks;
  • Use a web Domain Name System (DNS) reputation system;
  • Obtain and apply updates from authenticated vendor sites;
  • Validate the authenticity of downloads;
  • Insist that vendors digitally sign updates, and/or publish hashes via an out-of-bound communications path, and only use this path to authenticate; and
  • Never load updates from unverified sources.
    • Reduce your attack surface area
    • To the greatest extent possible, NCCIC recommends operators:
  • Isolate ICS networks from any untrusted networks, especially the Internet;
  • Lock down all unused ports;
  • Turn off all unused services; and
  • Only allow real-time connectivity to external networks if there is a defined business requirement or control function.
    • If one-way communication can accomplish a task, operators should use optical separation (“data diode”).
    • If bidirectional communication is necessary, operators should use a single open port over a restricted network path.

Build a Defendable Environment

Building a defendable environment will help limit the impact from network perimeter breaches. NCCIC recommends operators segment networks into logical enclaves and restrict host-to-host communications paths. This can prevent adversaries from expanding their access, while allowing the normal system communications to continue operating. Enclaving limits possible damage, as threat actors cannot use compromised systems to reach and contaminate systems in other enclaves. Containment provided by enclaving also makes incident cleanup significantly less costly.

If one-way data transfer from a secure zone to a less secure zone is required, operators should consider using approved removable media instead of a network connection. If real-time data transfer is required, operators should consider using optical separation technologies. This allows replication of data without placing the control system at risk.

Additional details on effective strategies for building a defendable ICS network can be found in the ICS-CERT Defense-in-Depth Recommended Practice.

Implement Secure Remote Access

Some adversaries are effective at gaining remote access into control systems, finding obscure access vectors, even “hidden back doors” intentionally created by system operators. Operators should remove such accesses wherever possible, especially modems, as these are fundamentally insecure.
Operators should:

  • Limit any accesses that remain;
  • Where possible, implement “monitoring only” access enforced by data diodes, and not rely on “read only” access enforced by software configurations or permissions;
  • Not allow remote persistent vendor connections into the control network;
  • Require any remote access to be operator controlled, time limited, and procedurally similar to “lock out, tag out;
  • Use the same remote access paths for vendor and employee connections; do not allow double standards; and
  • Use two-factor authentication if possible, avoiding schemes where both tokens are similar and can be easily stolen (e.g., password and soft certificate).

Monitor and Respond

Defending a network against modern threats requires actively monitoring for adversarial penetration and quickly executing a prepared response. Operators should

  • Consider establishing monitoring programs in the following key places: at the internet boundary; at the business to Control DMZ boundary; at the Control DMZ to control LAN boundary; and inside the Control LAN;
  • Watch IP traffic on ICS boundaries for abnormal or suspicious communications;
  • Monitor IP traffic within the control network for malicious connections or content;
  • Use host-based products to detect malicious software and attack attempts;
    • Use login analysis (time and place for example) to detect stolen credential usage or improper access, verifying all anomalies with quick phone calls;
    • Watch account/user administration actions to detect access control manipulation; and
  • Have a response plan for when adversarial activity is detected.
    • Such a plan may include disconnecting all Internet connections, running a properly scoped search for malware, disabling affected user accounts, isolating suspect systems, and immediately resetting 100 percent of passwords.
    • Such a plan may also define escalation triggers and actions, including incident response, investigation, and public affairs activities.
  • Have a restoration plan, including “gold disks” ready to restore systems to known good states.
     

References

Revision History

  • July 12, 2017: Initial Release

This product is provided subject to this Notification and this Privacy & Use policy.

Two Tickets as Bait

Over the previous weekend, social networks were hit with a wave of posts that falsely claimed that major airlines were giving away tickets for free. Users from all over the world became involved in this: they published posts that mentioned Emirates, Air France, Aeroflot, S7 Airline, Eva Air, Turkish Airlines, Air Asia, Air India, and other companies. We cannot rule out that similar posts mentioning other brands may appear in the nearest future as well.

Naturally, there have been no promotions to give away airline tickets. Users were addressed by fraudsters who assumed the names of the largest airlines in order to subscribe their victims to paid mobile services, collect personal data, install malware, and increase traffic to websites with advertisements and dubious content. To do this, fraudsters have been registering a multitude of domains, where they host content on behalf of well-known brands. At the mentioned resources, users are congratulated on winning two airline tickets. Then, they’re asked to perform a series of actions to receive the gift. As a result, the victim ends up on another website that belongs to fraudsters, which monetizes their “work” and spreads information about the nonexistent campaign on a social network.

An example of a social-network post with a link to a fraudulent website

This is by no means the first case where users themselves have started spreading fraudulent content on social networks. We have previously about a fake petition in defense of Suarez, which was distributed by Facebook users, fake donations, and pornware. All of the incidents have one thing in common: the threats are distributed over social networks, which users themselves often participate in.

The attack model

Let us return to the most recent case and examine it a bit closer. By following the link from a social network news feed, a user navigates to a fraudulent website. We have found a series of domains that belong to fraudsters: deltagiveaway.com, vvxwx9.us, aeroflot-com.us, aeroflot-ticket.us, qq3mz9.us, emiratesnow.us, emiratesgo.us, com-beforeitsends.us, emirates.iwelltrip.us, and many others.

Some examples of fraudulent websites that make use of famous airline brands

Since the fraudulent schemes only varied by logo, language, and color scheme, depending on the brand, let’s take one website out of the many and discuss it. The website that claims to belong to American Airlines contains information about a promotional giveaway of two tickets to respondents who must answer three questions.

An example of a fraudulent website that uses American Airlines branding.

After completing the survey, the victim is asked to take two more steps. First, the victim is asked to post the promotional information on his or her page on a social network and thank the airline in the comment. Secondly, the victim has to click the “Like” button. It should be noted that the web page shows what appear to be Facebook comments from users who have already won tickets. An investigation showed that the comments are actually fake. We can even leave our own comment, but it will disappear after the page is refreshed. All of this is directed at coaxing a victim into believing that the page is legitimate.

We would like to note that most comments are posted in various languages by the same people, and the messages are similar in content and most likely are translated using machine translation.

After performing all of the necessary actions, the website redirects the user to various web pages by using the geolocation feature. In some cases, we were redirected to the websites shown below.

Each time all of the same aforementioned actions are performed and the same survey is completed, the website does something different and may redirect users to various web pages. We have found websites with a variety of dubious content, including lotteries, advertisements, new surveys with giveaways, links to suspicious files that can be downloaded, and so on.

Among other things, some websites suggests users download a certain useful file and at the same time urge them to install a potentially dangerous extension for a browser. The extension obtains permission to read all of the data in a browser, potentially allowing fraudsters to get a hold of passwords, logins, credit-card data, and other confidential information entered by the user. Aside from that, later on, the extension may continue spreading links that redirect users to the extension itself on Facebook but on behalf of the user and among his or her friends. This is exactly the threat that was carried out by an attack that we discussed previously.

At the moment of publication, this indicated extension alone had been installed on the systems of over 5,000 users, according to the statistics of the web apps store.

The number of victims and their location

Most resources that utilize the fraudulent scheme contain links to external services that collect statistics for website traffic. These data show that the attack was widely distributed and was mostly directed at smartphone users. For example, here are some impressive statistics for only two of all the domains that we discovered.

Statistics for the aeroflot-ticket.us website

Statistics for the aeroflot-ticket.us website

Statistics for the emirateswow.us website

Unfortunately, numerous users took the bait of the fraudsters. These users tried their luck and did not pay attention to a multitude of signs that are typical for a scam, which resulted in spreading potentially dangerous content among friends over a social network.

Some examples of published posts with links to fraudulent websites

Thus, fraudulent web resources and a plethora of their counterparts across the Internet gained huge popularity in a matter of hours.
The possibilities of social networks are endless when it comes to spreading information across the globe. These fraudsters only confirm this fact.

Some examples of published posts with links to fraudulent websites

Finally, here are a few pieces of advice.

  • You should be sensibly skeptical about similar “promotions”. Before navigating to suspicious links and entering your personal data on a web resource, you should contact a representative of the company that is supposedly running the promotion and confirm the information.
  • A scrupulous examination of a web resource’s address will help identify fraud. It may be a good idea to verify whether the domain belongs to the company indicated on the website or not. Services that provide whois data about domains may prove helpful in that endeavor.
  • Be responsible when posting content from your account on a social network. In order to avoid becoming involved in a fraudulent scheme, do not spread information with questionable authenticity.
  • Do not install suspicious browser extensions. Upon detection of an installed extension that seems suspicious or whose purpose you do not remember, delete the extension immediately in the settings section of your browser and change the passwords of websites that you visit, especially those dealing with online banking.
  • Use security solutions that protect users from phishing, such as Internet Security-level solutions and higher. They will block any attempts to navigate your browser to fraudulent websites.

SambaCry is coming

Not long ago, news appeared online of a younger sibling for the sensational vulnerability EternalBlue. The story was about a new vulnerability for *nix-based systems – EternalRed (aka SambaCry). This vulnerability (CVE-2017-7494) relates to all versions of Samba, starting from 3.5.0, which was released in 2010, and was patched only in the latest versions of the package (4.6.4/4.5.10/4.4.14).

On May 30th our honeypots captured the first attack to make use of this particular vulnerability, but the payload in this exploit had nothing in common with the Trojan-Crypt that was EternalBlue and WannaCry. Surprisingly, it was a cryptocurrency mining utility!

Vulnerability exploitation

In order to check that an unauthorized user has permissions to write to the network drive, the attackers first try to write a text file, consisting of 8 random symbols. If the attempt is successful they delete the file.

Writing and deleting the text file

After this check, it is time for the exploit’s payload (it is assembled as a Samba plugin). After successful exploitation of the vulnerability, this runs with super-user privileges, although first the attackers have to guess the full path to the dropped file with their payload, starting from the root directory of the drive. We can see such attempts in the traffic captured on our honeypot. They are just brute-forcing the most obvious paths (specified in different manuals, etc.), where files can be stored on the drive.

Bruteforcing the path to the payload

After the path to the file is found, it can be loaded and executed in the context of the Samba-server process, using the SambaCry vulnerability. Afterwards the file is deleted in order to hide the traces. From this moment it exists and runs only in the virtual memory.

In our case two files were uploaded and executed in such a way: INAebsGB.so (349d84b3b176bbc9834230351ef3bc2a – Backdoor.Linux.Agent.an) and cblRWuoCc.so (2009af3fed2a4704c224694dfc4b31dc – Trojan-Downloader.Linux.EternalMiner.a).

INAebsGB.so

This file stores the simplest reverse-shell. It connects to the particular port of the IP-address specified by its owner, giving him remote access to the shell (/bin/sh). As a result, the attackers have an ability to execute remotely any shell-commands. They can literally do anything they want, from downloading and running any programs from the Internet, to deleting all the data from the victim’s computer.

Listing of INAebsGB.so

It’s worth noting that a similar payload can be found in the implementation of the SambaCry exploit in Metasploit.

cblRWuoCc.so

The main functionality of this file is to download and execute one of the most popular open-source cryptocurrency mining utilities – cpuminer (miderd). It is done by the hardcoded shell-command, shown on the screenshot below.

The main functionality of cblRWuoCc.so

The file minerd64_s (8d8bdb58c5e57c565542040ed1988af9 — RiskTool.Linux.BitCoinMiner.a) downloaded in such a way is stored in /tmp/m on the victim’s system.

Cpuminer and what it actually mines

The interesting part is that the version of cpuminer used is “upgraded”, so it can be launched without any parameters to mine currency directly to the hardcoded attackers’ wallet. We obviously became interested in this wallet, so we decided to investigate a bit and uncover the balance of the attackers account.

Along with the attackers’ wallet number, the pool address (xmr.crypto-pool.fr:3333) can be found in the body of the miner. This pool is created for mining the open-source cryptocurrency – monero. Using all this data we managed to check out the balance on the attackers’ wallet and the full log of transactions. Let’s have a look:

Balance of the attackers’ account on 08.06.2017

Log of transactions with all the attackers’ cryptocurrency income

The mining utility is downloaded from the domain registered on April 29th 2017. According to the log of the transactions, the attackers received their first crypto-coins on the very next day, on April 30th. During the first day they gained about 1 XMR (about $55 according to the currency exchange rate for 08.06.2017), but during the last week they gained about 5 XMR per day. This means that the botnet of devices working for the profit of the attackers is growing.

Considering that the world discovered the EternalRed vulnerability only at the end of May, and the attackers had already adopted it, the rate of growth in the number of infected machines has significantly increased. After about a month of mining, the attackers gained 98 XMR, which means they earned about $5,500 according to the currency exchange rate at the time of writing.

Conclusion

As a result, the attacked machine turns into a workhorse on a large farm, mining crypto-currency for the attackers. In addition, through the reverse-shell left in the system, the attackers can change the configuration of a miner already running or infect the victim’s computer with other types of malware.

At the moment we don’t have any information about the actual scale of the attack. However, this is a great reason for system administrators and ordinary Linux users to update their Samba software to the latest version immediately to prevent future problems.

Dvmap: the first Android malware with code injection

no-image

In April 2017 we started observing new rooting malware being distributed through the Google Play Store. Unlike other rooting malware, this Trojan not only installs its modules into the system, it also injects malicious code into the system runtime libraries. Kaspersky Lab products detect it as Trojan.AndroidOS.Dvmap.a.

The distribution of rooting malware through Google Play is not a new thing. For example, the Ztorg Trojan has been uploaded to Google Play almost 100 times since September 2016. But Dvmap is very special rooting malware. It uses a variety of new techniques, but the most interesting thing is that it injects malicious code into the system libraries – libdmv.so or libandroid_runtime.so.

This makes Dvmap the first Android malware that injects malicious code into the system libraries in runtime, and it has been downloaded from the Google Play Store more than 50,000 times. Kaspersky Lab reported the Trojan to Google, and it has now been removed from the store.

Dvmap: the first Android malware with code injection

Trojan.AndroidOS.Dvmap.a on Google Play

To bypass Google Play Store security checks, the malware creators used a very interesting method: they uploaded a clean app to the store at the end of March, 2017, and would then update it with a malicious version for short period of time. Usually they would upload a clean version back on Google Play the very same day. They did this at least 5 times between 18 April and 15 May.

All the malicious Dvmap apps had the same functionality. They decrypt several archive files from the assets folder of the installation package, and launch an executable file from them with the name “start.”

Dvmap: the first Android malware with code injection

Encrypted archives in the assets folder

The interesting thing is that the Trojan supports even the 64-bit version of Android, which is very rare.

Dvmap: the first Android malware with code injection

Part of code where the Trojan chooses between 32-bit and 64-bit compatible files

All encrypted archives can be divided into two groups: the first comprises Game321.res, Game322.res, Game323.res and Game642.res – and these are used in the initial phase of infection, while the second group: Game324.res and Game644.res, are used in the main phase.

Initial phase

During this phase, the Trojan tries to gain root rights on the device and to install some modules. All archives from this phase contain the same files except for one called “common”. This is a local root exploit pack, and the Trojan uses 4 different exploit pack files, 3 for 32-bit systems and 1 for 64-bit-systems. If these files successfully gain root rights, the Trojan will install several tools into the system. It will also install the malicious app “com.qualcmm.timeservices.”

These archives contain the file “.root.sh” which has some comments in Chinese:

Dvmap: the first Android malware with code injection

Part of .root.sh file

Main phase

In this phase, the Trojan launches the “start” file from Game324.res or Game644.res. It will check the version of Android installed and decide which library should be patched. For Android 4.4.4 and older, the Trojan will patch method _Z30dvmHeapSourceStartupBeforeForkv from libdvm.so, and for Android 5 and newer it will patch method nativeForkAndSpecialize from libandroid_runtime.so. Both of these libraries are runtime libraries related to Dalvik and ART runtime environments. Before patching, the Trojan will backup the original library with a name bak_{original name}.

Dvmap: the first Android malware with code injection

Patched libdvm.so

During patching, the Trojan will overwrite the existing code with malicious code so that all it can do is execute /system/bin/ip. This could be very dangerous and cause some devices to crash following the overwrite. Then the Trojan will put the patched library back into the system directory. After that, the Trojan will replace the original /system/bin/ip with a malicious one from the archive (Game324.res or Game644.res). In doing so, the Trojan can be sure that its malicious module will be executed with system rights. But the malicious ip file does not contain any methods from the original ip file. This means that all apps that were using this file will lose some functionality or even start crashing.

Malicious module “ip”

This file will be executed by the patched system library. It can turn off “VerifyApps” and enable the installation of apps from 3rd party stores by changing system settings. Furthermore, it can grant the “com.qualcmm.timeservices” app Device Administrator rights without any interaction with the user, just by running commands. It is a very unusual way to get Device Administrator rights.

Malicious app com.qualcmm.timeservices

As I mentioned before, in the “initial phase”, the Trojan will install the “com.qualcmm.timeservices” app. Its main purpose is to download archives and execute the “start” binary from them. During the investigation, this app was able to successfully connect to the command and control server, but it received no commands. So I don’t know what kind of files will be executed, but they could be malicious or advertising files.

Conclusions

This Trojan was distributed through the Google Play Store and uses a number of very dangerous techniques, including patching system libraries. It installs malicious modules with different functionality into the system. It looks like its main purpose is to get into the system and execute downloaded files with root rights. But I never received such files from their command and control server.

These malicious modules report to the attackers about every step they are going to make. So I think that the authors are still testing this malware, because they use some techniques which can break the infected devices. But they already have a lot of infected users on whom to test their methods.

I hope that by uncovering this malware at such an early stage, we will be able to prevent a massive and dangerous attack when the attackers are ready to actively use their methods.

MD5

43680D1914F28E14C90436E1D42984E2
20D4B9EB9377C499917C4D69BF4CCEBE

50 hashes per hour

How often do you turn off your computer when you go home from work? We bet you leave it on so you don’t have to wait until it boots up in the morning. It’s possible that your IT staff have trained you to lock your system for security reasons whenever you leave your workplace. But locking your system won’t save your computer from a new type of attack that is steadily gaining popularity on Raspberry Pi enthusiast forums.

We previously investigated the security of charging a smartphone via a USB port connection. In this research we’ll be revisiting the USB port – this time in attempts to intercept user authentication data on the system that a microcomputer is connected to. As we discovered, this type of attack successfully allows an intruder to retrieve user authentication data – even when the targeted system is locked. It also makes it possible to get hold of administrator credentials. Remember Carbanak, the great bank robbery of 2015, when criminals were able to steal up to a billion dollars? Finding and retrieving the credentials of users with administrative privileges was an important part of that robbery scheme.

In our research we will show that stealing administrator credentials is possible by briefly connecting a microcomputer via USB to any computer within the corporate perimeter. By credentials in this blogpost we mean the user name and password hash and we won’t go into detail how to decipher the retrieved hash, or how to use it in the pass-the-has types of attacks. What we’re emphasizing is that the hardware cost of such an attack is no more than $20 and it can be carried out by a person without any specific skills or qualifications. All that’s needed is physical access to corporate computers. For example, it could be a cleaner who is asked to plug “this thing” into any computer that’s not turned off.

50 hashes per hour

We used a Raspberry Pi Zero in our experiments. It was configured to enumerate itself as an Ethernet adapter on the system it was being plugged into. This choice was dictated by the popularity of Raspberry Pi Zero mentions on forums where enthusiasts discuss the possibility of breaking into information systems with single-board computers. This popularity is understandable, given the device capabilities, size and price. Its developers were able to crank the chip and interfaces into a package that is slightly larger than an ordinary USB flash drive.

50 hashes per hour

Yes, the idea of using microcomputers to intercept and analyze network packets or even as a universal penetration testing platform is nothing new. Most known miniature computing devices are built on ARM microprocessors, and there is a special build of Kali Linux that is specifically developed for pen testing purposes.

There are specialized computing sticks that are designed specifically for pen testing purposes, for example, USB Armory. However, with all its benefits, like integrated USB Type A connector (Raspberry Pi requires an adapter), USB Armory costs much more (around $135) and absolutely pales in comparison when you look at its availability vs. Raspberry Pi Zero. Claims that Raspberry Pi can be used to steal hashes when connected via USB to a PC or Mac surfaced back in 2016. Soon there were claims that Raspberry Pi Zero could also be used for stealing cookies fromh3 browsers – something we also decided to investigate.

So, armed with one of the most widespread and available microcomputers at the moment, we conducted two series of experiments. In the first, we attempted to intercept user credentials within the corporate network, trying to connect to laptop and desktop computers running different operating systems. In the second, we attempted to retrieve cookies in a bid to restore the user session on a popular website.

Experiment 1: stealing domain credentials

Methodology

The key principle behind this attack is emulation of the network adapter. We had absolutely no difficulties in finding the module emulating the Ethernet adapter under Raspbian OS (for reference, at the time of writing, we hadn’t found a similar module for Kali Linux). We made a few configuration changes in the cmdline.txt and config.txt files to load the module on boot.

50 hashes per hour

50 hashes per hour

A few extra steps included installing the python interpreter, sqlite3 database library and a special app called Responder for packet sniffing:

apt-get install -y python git python-pip python-dev screen sqlite3
pip install pycrypto
git clone
https://github.com/spiderlabs/responder

And that wasn’t all – we set up our own DHCP server where we defined the range of IP addresses and a mask for a subnet to separate it from the network we’re going to peer into. The last steps included configuring the usb0 interface and automatic loading of Responder and DHCP server on boot. Now we were ready to rock.

Results

Just as soon as we connected our “charged” microcomputer to Windows 10, we saw that the connected Raspberry Pi was identified as a wired LAN connection. The Network Settings dialogue shows this adapter as Remote NDIS Internet sharing device. And it’s automatically assigned a higher priority than others.

50 hashes per hour

Responder scans the packets that flow through the emulated network and, upon seeing the username/password hash pairs, directs them to a fake HTTP/HTTPS/NTLM (it supports v1 and v2) server. The attack is triggered every time applications, including those running in the background, send authentication data, or when a user enters them in the standard dialogue windows in the web browser – for example, when user attempts to connect to a shared folder or printer.

50 hashes per hour

Intercepting the hash in automatic mode, which is effective even if the system is locked, only works if the computer has another active local network connection.

As stated above, we tried this proof of concept in three scenarios:

  1. Against a corporate computer logged into a domain
  2. Against a corporate computer on a public network
  3. Against a home computer

In the first scenario we found that the device managed to intercept not only the packets from the system it’s connected to via USB but also NTLM authentication requests from other corporate network users in the domain. We mapped the number of intercepted hashes against the time elapsed, which is shown in the graph below:

Playing around with our “blackbox” for a few minutes, we got proof that the longer the device is connected, the more user hashes it extracts from the network. Extrapolating the “experimental” data, we can conclude that the number of hashes it can extract in our setting is around 50 hashes per hour. Of course, the real numbers depend on the network topology, namely, the amount of users within one segment, and their activity. We didn’t risk running the experiment for longer than half an hour because we also stumbled on some peculiar side effects, which we will describe in a few moments.

The extracted hashes are stored in a plain-text file:

50 hashes per hour

In the second scenario we were only able to extract the connected system’s user credentials: domain/Windows name and password hash. We might have gotten more if we had set up shared network resources which users could try to access, but we’re going to leave that outside the scope of this research.

In the third scenario, we could only get the credentials of the owner of the system, which wasn’t connect to a domain authentication service. Again, we assume that setting up shared network resources and allowing other users to connect to them could lead to results similar to those we observed in the corporate network.

The described method of intercepting the hashes worked on Mac OS, too. When we tried to reach an intranet site which requires entering a domain name, we saw this dialogue warning that the security certificate is invalid.

50 hashes per hour

Now, the interesting side effect we mentioned above was that when the device was connected to a[ny] system in the network, tasks sent out to the network printer from other machines in the same network were put on hold in the printer queue. When the user attempted to enter the credentials in the authentication dialogue window, the queue didn’t clear. That’s because these credentials didn’t reach the network printer, landing in the Raspberry Pi’s flash memory instead. Similar behavior was observed when trying to connect to remote folders via the SMB protocol from a Mac system.

50 hashes per hour

Bonus: Raspberry Pi Zero vs. Raspberry Pi 3

Once we saw that the NTLM systems of both Windows and Mac had come under attack from the microcomputer, we decided to try it against Linux. Furthermore, we decided to attack the Raspberry Pi itself, since Raspbian OS is built on the Debian Weezy core.

We reproduced the experiment, this time targeting Raspberry Pi 3 (by the way, connecting it to the corporate network was a challenging task in itself, but doable, so we won’t focus on it here). And here we had a pleasant surprise – Raspbian OS resisted assigning the higher priority to a USB device network, always choosing the built-in Ethernet as default. In this case, the Responder app was active, but could do nothing because packets didn’t flow through the device. When we manually removed the built-in Ethernet connection, the picture was similar to that we had observed previously with Windows.

50 hashes per hour

Similar behavior was observed on the desktop version of Debian running on Chromebook – the system doesn’t automatically set the USB Ethernet adapter as default. Therefore, if we connect Raspberry Pi Zero to a system running Debian, the attack will fail. And we don’t think that creating Raspberry Pi-in-the-middle attacks is likely to take off, because they are much harder to implement and much easier to detect.

Experiment 2: stealing cookies

Methodology

While working on the first experiment, we heard claims that it’s possible to steal cookies from a PC when a Raspberry Pi Zero is connected to it via USB. We found an app called HackPi, a variant of PoisonTap (an XSS JavaScript) with Responder, which we described above.

The microcomputer in this experiment was configured just like in the previous one. HackPi works even better at establishing itself as a network adapter because it has an enhanced mechanism of desktop OS discovery: it is able to automatically install the network device driver on Windows 7/8/10, Mac and –nix operating systems. While in the first series of experiments, an attack could fail on Windows 7, 8 or Vista if the Remote NDIS Internet sharing device didn’t install itself automatically (especially when the PC is locked). And, unlike in the previous series, HackPi never had trouble assigning itself the default network adapter priority under Mac OS either.

What differs from the first experiment is that the cookies are stolen using the malicious Java Script launched from the locally stored web page. If successful, PoisonTap’s script saves the cookies intercepted from sites, a list of which is also locally stored.

Results

If the computer is not locked and the user opens the browser, Java Script initiates the redirecting of web requests to a malicious local web page. Then the browser opens the websites from the previously defined list. It is indeed quite spectacular:

50 hashes per hour

If the user does nothing, Raspberry Pi Zero launches the default browser with URL go.microsoft.com in the address line after a short timeout. Then the process goes ahead as described. However, if the default browser has no cookies in the browser history, the attackers gain nothing.

Among the sites we’ve seen in the list supplied with the script were youtube.com, google.com, vk.com, facebook.com, twitter.com, yandex.ru, mail.ru and over 100 other web addresses. This is what the log of stolen cookies looks like:

50 hashes per hour

We checked the validity of stolen cookies using the pikabu.ru website as an example by pasting the info into a clean browser field on other machines and were able to get hold of the user’s account along with all the statistics. On another website belonging to a railroad company vending service, we were able to retrieve the user’s token and take over the user’s account on another computer, because authentication protocol used only one LtpaToken2 for session identification.

50 hashes per hour

Now this is more serious, because in this case the criminals can get information about previous orders made by the victim, part of their passport number, name, date of birth, email and phone number.

50 hashes per hour

One of the strong points of this attack is that enthusiasts have learned how to automatically install the network device driver on all systems found in today’s corporate environments: Windows 7/8/10, Mac OS X. However, this scenario doesn’t work against a locked system – at least, for now. But we don’t think you should become too complacent; we assume it’s only a matter of time before the enthusiasts overcome this as well. Especially given that the number of these enthusiasts is growing every day.

Also, the malicious web page is blocked by all Kaspersky Lab products, which detect it as Trojan.JS.Poisontap.a. We also assume that this malicious web page will be blocked by the products of all other major anti-malware vendors.

50 hashes per hour

Conclusions

There is already a wide array of single-board microcomputers: from the cheap and universal Raspberry Pi Zero to computing sticks specifically tuned for penetration testing, which cannot be visually differentiated from USB flash drives. To answer the main question of just how serious this threat is, we can say that at the moment it is overrated. However, we don’t advise underestimating the capabilities of IoT enthusiasts and it’s better to assume that those obstacles which we discovered in our experiment, have already been overcome.

Right now we can say that Windows PCs are the systems most prone to attacks aimed at intercepting the authentication name and password with a USB-connected Raspberry Pi. The attack works even if the user doesn’t have local or system administrator privileges, and can retrieve the domain credentials of other users, including those with administrator privileges. And it works against Mac OS systems, too.

50 hashes per hour

The second type of attack that steals cookies only works (so far) when the system is unlocked, which reduces the chances of success. It also redirects traffic to a malicious page, which is easily blocked by a security solution. And, of course, stolen cookies are only useful on those websites that don’t employ a strict HTTP transport policy.

Recommendations

However, there are a number of recommendations we’d like to give you to avoid becoming easy prey for attackers.

Users

1. Never leave your system unlocked, especially when you need to leave your computer for a moment and you are in a public place.

2. On returning to your computer, check to see if there are any extra USB devices sticking out of your ports. See a flash drive, or something that looks like a flash drive? If you didn’t stick it in, we suggest you remove it immediately.

3. Are you being asked to share something via external flash drive? Again, it’s better to make sure that it’s actually a flash drive. Even better – send the file via cloud or email.

4. Make a habit of ending sessions on sites that require authentication. Usually, this means clicking on a “Log out” button.

5. Change passwords regularly – both on your PC and the websites you use frequently. Remember that not all of your favorite websites may use mechanisms to protect against cookie data substitution. You can use specialized password management software for easy management of strong and secure passwords, such as the free Kaspersky Password Manager.

6. Enable two-factor authentication, for example, by requesting login confirmation or with a hardware token.

7. Of course, it’s strongly recommended to install and regularly update a security solution from a proven and trusted vendor.

Administrators

1. If the network topology allows it, we suggest using solely Kerberos protocol for authenticating domain users. If, however, there is a demand for supporting legacy systems with LLNMR and NTLM authentication, we recommend breaking down the network into segments, so that even if one segment is compromised, attackers cannot access the whole network.

2. Restrict privileged domain users from logging in to the legacy systems, especially domain administrators.

3. Domain user passwords should be changed regularly. If, for whatever reason, the organization’s policy does not involve regular password changes, please change the policy. Like, yesterday.

4. All of the computers within a corporate network have to be protected with security solutions and regular updates should be ensured.

5. In order to prevent the connection of unauthorized USB devices, it can be useful to activate a Device Control feature, available in the Kaspersky Endpoint Security for Business suite.

6. If you own the web resource, we recommend activating the HSTS (HTTP strict transport security) which prevents switching from HTTPS to HTTP protocol and spoofing the credentials from a stolen cookie.

7. If possible, disable the listening mode and activate the Client (AP) isolation setting in Wi-Fi routers and switches, disabling them from listening to other workstations’ traffic.

8. Activate the DHCP Snooping setting to protect corporate network users from capturing their DHCP requests by fake DHCP servers.

Last, but not least, you never know if your credentials have been leaked from a site you’ve been to before – online or physical. Thus, we strongly recommend that you check your credentials on the HaveIbeenPwned website to be sure.

TA17-156A: Reducing the Risk of SNMP Abuse

Original release date: June 05, 2017

Systems Affected

SNMP enabled devices

Overview

The Simple Network Management Protocol (SNMP) may be abused to gain unauthorized access to network devices. SNMP provides a standardized framework for a common language that is used for monitoring and managing devices in a network.

This Alert provides information on SNMP best practices, along with prevention and mitigation recommendations.

Description

SNMP depends on secure strings (or “community strings”) that grant access to portions of devices’ management planes. Abuse of SNMP could allow an unauthorized third party to gain access to a network device. 

SNMPv3 should be the only version of SNMP employed because SNMPv3 has the ability to authenticate and encrypt payloads. When either SNMPv1 or SNMPv2 are employed, an adversary could sniff network traffic to determine the community string. This compromise could enable a man-in-the-middle or replay attack.

Although SNMPv1 and SNMPv2 have similar characteristics, 64-bit counters were added to SNMPv2 so it could support faster interfaces. SNMPv3 replaces the simple/clear text password sharing used in SNMPv2 with more securely encoded parameters. All versions run over the User Datagram Protocol (UDP).

Simply using SNMPv3 is not enough to prevent abuse of the protocol. A safer approach is to combine SNMPv3 with management information base (MIB) whitelisting using SNMP views. This technique ensures that even with exposed credentials, information cannot be read from or written to the device unless the information is needed for monitoring or normal device re-configuration. The majority of devices that support SNMP contain a generic set of MIBs that are vendor agnostic. This approach allows the object identifier (OID) to be applied to devices regardless of manufacturer.

Impact

A remote attacker may abuse SNMP-enabled network devices to access an organization’s network infrastructure.

Solution

A fundamental way to enhance network infrastructure security is to safeguard networking devices with secure configurations. US-CERT recommends that administrators:

  • Configure SNMPv3 to use the highest level of security available on the device; this would be authPriv on most devices. authPriv includes authentication and encryption features, and employing both features enhances overall network security. Some older images may not contain the cryptographic feature set, in which case authNoPriv needs to be used. However, if the device does not support Version 3 authPriv, it should be upgraded.
  • Ensure administrative credentials are properly configured with different passwords for authentication and encryption. In configuring accounts, follow the principle of least privilege. Role separation between polling/receiving traps (reading) and configuring users or groups (writing) is imperative because many SNMP managers require login credentials to be stored on disk in order to receive traps.
  • Refer to your vendor’s guidance for implementing SNMP views. SNMP view is a command that can be used to limit the available OIDs. When OIDs are included in the view, all other MIB trees are inherently denied. The SNMP view command must be used in conjunction with a predefined list of MIB objects.
  • Apply extended access control lists (ACLs) to block unauthorized computers from accessing the device. Access to devices with read and/or write SNMP permission should be strictly controlled. If monitoring and change management are done through separate software, then they should be on separate devices.
  • Segregate SNMP traffic onto a separate management network. Management network traffic should be out-of-band; however, if device management must coincide with standard network activity, all communication occurring over that network should use some encryption capability. If the network device has a dedicated management port, it should be the sole link for services like SNMP, Secure Shell (SSH), etc.
  • Keep system images and software up-to-date.

References

Revision History

  • June 5, 2017: Initial Release

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