Following the arrest in 2018 of a number of suspected leaders of the notorious Fin7/Carbanak cyber-gang, the group was believed to have disbanded. But Kaspersky Lab researchers have detected a number of new attacks by the same groups using GRIFFON malware.
According to the company’s experts, Fin7 might have extended the number of groups operating under its umbrella; increased the sophistication of its methods; and even positioned itself as a legitimate security vendor to recruit professional employees and dupe them into helping it steal financial assets.
Fin7 is believed to be behind attacks targeting the U.S. retail, restaurant, and hospitality sectors since mid-2015, working in close collaboration and sharing tools and methods with the infamous Carbanak group. While Carbanak focused primarily on banks, Fin7 targeted mostly businesses, potentially making off with millions of dollars in financial assets, such as payment card credentials or account information on the computers of financial departments. Once the threat actors got what they needed, they wired money to offshore accounts.
According to Kaspersky Lab’s new investigation, the group has continued its activity – despite the arrest last year of alleged group leaders – implementing sophisticated spear-phishing campaigns throughout 2018 and distributing malware to each target through specially tailored emails. In different cases, the operators exchanged messages with their intended victims over a period of weeks before finally sending the malicious documents as attachments. Kaspersky Lab estimates that by the end of 2018, more than 130 companies might have been targeted in this way.
The researchers also discovered other criminal teams operating under the Fin7 umbrella. The use of shared infrastructure and the same tactics techniques and procedures (TTPs), shows that Fin7 is likely to be collaborating with the AveMaria botnet and groups known as CobaltGoblin/EmpireMonkey, believed to be behind bank robberies in Europe and Central America.
Kaspersky Lab also found that Fin7 has created a fake company that claims to be a legitimate cybersecurity vendor with offices across Russia. The company website is registered to the server that Fin7 uses as a Command and Control center (C&C). The fake business has been used to recruit unsuspecting freelance vulnerability researchers, program developers and interpreters through legitimate online job sites. It seems that some of the individuals working in these fake companies did not suspect that they were involved in a cybercrime business, with many including the experience of working in the organizations in their CVs.
“Modern cyberthreats can be compared to the mythical creature Hydra of Lerna – you cut off one of its heads and it grows two new ones. Therefore, the best way to protect yourself from such actors is to implement advanced, multi-layered protection: install all software patches as soon as they are released and do regular security analysis across all networks, systems and devices,” said Yury Namestnikov, security researcher at Kaspersky Lab.
Recent FIN7 campaigns
The FIN7 intrusion set continued its tailored spear phishing campaigns throughout last year. Kaspersky Lab has been able to retrieve some of these exchanges from a FIN7 target. The spear phishing campaigns were remarkably sophisticated from a social engineering perspective. In various cases, the operators exchanged numerous messages with their victims for weeks before sending their malicious documents. The emails were efficient social-engineering attempts that appealed to a vast number of human emotions (fear, stress, anger, etc.) to elicit a response from their victims. One of the domains used by the attackers in their 2018 campaign of spear phishing contained more than 130 email aliases, leading us to think that more than 130 companies had been targeted by the end of 2018.
We have seen two types of documents sent to victims in these spear phishing campaigns. The first one exploits the INCLUDEPICTURE feature of Microsoft Word to get context information about the victim’s computer, and the availability and version number of Microsoft Word. The second one, which in many cases is an Office document protected with a trivial password, such as “12345”, “1234”, etc., uses macros to execute a GRIFFON implant on the target’s computer. In various cases, the associated macro also scheduled tasks to make GRIFFON persistent.
Interestingly, following some open-source publications about them, the FIN7 operators seems to have developed a homemade builder of malicious Office document using ideas from ThreadKit, which they employed during the summer of 2018. The new builder inserts random values in the Author and Company metadata fields. Moreover, the builder allows these to modify different IOCs, such as the filenames of wscript.exe or sctasks.exe copies, etc.
IOCs extracted from docs which use sctasks for GRIFFON persistence
IOCs extracted from regular documents associated to GRIFFON
The GRIFFON implant is a lightweight JScript validator-style implant without any persistence mechanism. The malware is designed for receiving modules to be executed in-memory and sending the results to C2s. We were able to obtain four different modules during the investigation.
The first module downloaded by the GRIFFON malware to the victim’s computer is an information-gathering JScript, which allows the cybercriminals to understand the context of the infected workstation. This module mainly relies on WMI and Windows objects to deliver results, which will be sent back to the operators. Interestingly, more than 20 artifacts are retrieved from the system by this implant during the reconnaissance stage, from the date and time of operating system installation and membership in a Windows domain to a list of and the resolutions of the workstation’s monitors.
The second module is used by the operators to execute an obfuscated PowerShell script, which contains a Meterpreter downloader widely known as “Tinymet“. This downloader, seen in past FIN7 campaigns, downloads a one-byte XOR-encrypted (eg. with the key equal to 0x50 or 0x51) piece of meterpreter shellcode to execute.
The third module allows the operators to take a screenshot of the remote system. To do that, it also drops a PowerShell script on the workstation to execute. The script executes an open-source .NET class used for taking a screenshot. The resulting screenshot is saved at “%TMP%/image.png”, sent back to the attackers by the GRIFFON implant and then deleted.
The last retrieved module is a persistence module. If the victim appears valuable to the attackers, a GRIFFON implant installer is pushed to the victim’s workstation. This module stores another instance of the GRIFFON implant inside the registry to achieve persistence. Here is a PowerLinks-style method used by the attackers to achieve persistence and execute the GRIFFON implant at each user logon. The new GRIFFON implant is written to the hard drive before each execution, limiting the “file-less” aspect of this method.
Through its light weight and modular architecture, the GRIFFON implant is the perfect validator. Even though we have been able to retrieve four different modules, it is possible that the FIN7 operators have more modules in their toolsets for achieving their objectives on the victim’s workstation.
On the hunt for GRIFFON infrastructure
Attackers make mistakes, and FIN7 are no exception. The major error made by its operators allowed us to follow the command and control server of the GRIFFON implant last year. In order to trick blue teams and other DFIR analysts, the operators created fake HTTP 302 redirection to various Google services on their C2s servers.
HTTP/1.1 302 Found
Content–Type: text/html; charset=UTF–8
Returned headers for most of the GRIFFON C2s servers on port 443
This error allowed us to follow the infrastructure week by week, until an individual pushed on Twitter the heuristic to track their C2 at the end of December 2018. A few days after the tweet, in January 2019, the operators changed their landing page in order to prevent this type of tracking against their infrastructure.
Fake pentest company
During the investigation related to the GRIFFON infrastructure, we found a strange overlap between the WHOIS record of an old GRIFFON C2 and the website of a fake company.
According to the website, that domain supposedly belongs to a legitimate security company “fully owned by the Russian Government” (sic.) and having offices in “Moscow, Saint Petersburg and Yekaterinburg”, but the address says the company is located in Trump Tower, in New York. Given FIN7’s previous use of false security companies, we decided to look deeper into this one.
As we were looking at the content of the website, it became evident that almost all of the text used was lifted from legitimate security-company websites. Phrases and sentences were borrowed from at least the following companies/sites:
- DKSec – www.dksec.com
- OKIOK – www.okiok.com/services/tailored-solutions
- MainNerve – www.mainnerve.com
- Datics – www.datatics.com/cyber-security
- Perspective Risk – www.perspectiverisk.com
- Synack – https://www.synack.com/company
- FireEye – https://www.fireeye.com/services/penetration-testing.html
This company seems to have been used by the FIN7 threat actor to hire new people as translators, developers and pentesters. During our research, we found various job advertisements associated with the company on freelance and remote-work websites.
In addition to that, various individuals have mentioned the company in their resumes. We believe that some of these individuals may not even be aware that they are working for a cybercrime business.
Links to other intrusion sets
While tracking numerous threat actors on a daily basis during the final days of 2018 and at the beginning of 2019, we discovered various activity clusters sharing certain TTPs associated with the FIN7 intrusion set. The link between these threat actors and FIN7 is still weak, but we decided to disclose a few hints regarding these in this blog post.
In his history, FIN7 has overlapped several times with Cobalt/EmpireMonkey in terms of TTPs. This activity cluster, which Kaspersky Lab has followed for a few years, uses various implants for targeting mainly banks, and developers of banking and money processing software solutions. At the end of 2018, the cluster started to use not only CobaltStrike but also Powershell Empire in order to gain a foothold on the victims’ networks. After a successful penetration, it uses its own backdoors and the CobaltStrike framework or Powershell Empire components to hop to interesting parts of the network, where it can monetize its access.
FIN7’s last campaigns were targeting banks in Europe and Central America. This threat actor stole suspected of stealing €13 million from Bank of Valetta, Malta earlier this year.
A few interesting overlaps in recent FIN7 campaigns:
- Both used macros to copy wscript.exe to another file, which began with “ms” (mses.exe – FIN7, msutil.exe – EmpireMonkey).
- Both executed a JScript file named “error” in %TEMP% (Errors.txt in the case of FIN7, Errors.bat for EmpireMonkey).
- Both used DocuSign decoy documents with different macros. The macros popped the same “Document decryption error” error message—even if macro code remain totally different.
We have a high level of confidence in a historic association between FIN7 and Cobalt, even though we believe that these two clusters of activity are operated by different teams.
AveMaria is a new botnet, whose first version we found in September 2018, right after the arrests of the FIN7 members. We have medium confidence that this botnet falls under the FIN7 umbrella. In fact, AveMaria is a classic infostealer bot that collects all possible credentials from various types of software: browsers, email clients, messengers, etc., and can act as a keylogger. Since the beginning of 2019, we have collected more than 1300 samples and extracted more than 130 C2s.
To deliver their malware, the cyber criminals use spearphishing emails with various types of attachments: MS Office documents or spreadsheet files exploiting some known vulnerability like CVE-2017-11882, or documents with Ole2Link and SCT. They also use AutoIT droppers, password-protected EXE files and even ISO images. What is interesting, in some emails, they ask targets to phone them if they have any questions, like the FIN7 guys do.
During the investigation into FIN7, our threat-hunting systems found an interesting overlap in between the infrastructure of FIN7 and AveMaria. Basically, two servers in the same IP range and AS14576 (autonomous system) share a non-standard SSH port, which is 222. One of the servers is a Griffon C2, and the other one, an AveMaria C2.
Distribution of targets is another factor suggesting that these two malware families may be connected. We analyzed AveMaria targets during February and March of 2019. The spearphishing emails were sent to various kinds of businesses only and did not target individuals. Thirty percent of the targets were small and medium-sized companies that were suppliers or service providers for bigger players and 21% were various types of manufacturing companies. We also spotted several typical FIN7 targets, such as retailers and hotels. Most AveMaria targets (72%) were in the EU.
At the end of 2018, while searching for new FIN7 campaigns via telemetry, we discovered a set of activity that we temporarily called “CopyPaste” from a previously unknown APT. Interestingly, this actor targeted financial entities and companies in one African country, which lead us to think that CopyPaste was associated with cybermercenaries or a training center.
This set of activity relied on open-source tools, such as Powershell Empire, and well-documented red teaming techniques, in order to get a foothold within the victim’s networks and avoid detection.
Here are the main similarities between CopyPaste and FIN7:
- Both used the same Microsoft PowerShell argument obfuscation order: “powershell.exe -NoP -NonI -ExecutionPolicy Bypass”. We have only seen FIN7 and CopyPaste use this argument list for executing their malicious Powershell Scripts.
- Both used decoy 302 HTTP redirections and typosquatting on their C2s (reminiscent of Cobalt and FIN7). The Empire C2s associated with CopyPaste had decoy redirections to Digitcert and Microsoft websites and used decoy job employment and tax websites with decoy redirections to host their payloads. FIN7 and Cobalt used decoy 302 HTTP redirections too, FIN7 on its GRIFFON C2s before January 2018, and Cobalt, on its staging servers, similar to CopyPaste.
- Quite recently, FIN7 threat actors typosquatted the brand “Digicert” using the domain name digicert-cdn[.]com, which is used as a command and control server for their GRIFFON implants. CopyPaste, in turn, also typosquatted this brand with their domains digicertweb[.]com and digi-cert[.]org, both used as a Powershell Empire C2 with decoy HTTP 302 redirects to the legitimate Digicert website.
The links between CopyPaste and FIN7 are still very weak. It is possible that the CopyPaste operators were influenced by open-source publications and do not have any ties with FIN7.
During 2018, Europol and DoJ announced the arrest of the leader of the FIN7 and Carbanak/CobaltGoblin cybercrime groups. It was believed that the arrest of the group leader will have an impact on the group’s operations. However, recent data seems to indicate that the attacks have continued without significant drawbacks. One may say CobaltGoblin and FIN7 have even extended the number of groups operating under their umbrella. We observe, with various level of confidence, that there are several interconnected groups using very similar toolkits and the same infrastructure to conduct their cyberattacks.
The first of them is the well-known FIN7, which specializes in attacking various companies to get access to financial data or PoS infrastructure. They rely on a Griffon JS backdoor and Cobalt/Meterpreter, and in recent attacks, Powershell Empire. The second one is CobaltGoblin/Carbanak/EmpireMonkey, which uses the same toolkit, techniques and similar infrastructure but targets only financial institutions and associated software/services providers.
We link the AveMaria botnet to these two groups with medium confidence: AveMaria’s targets are mostly suppliers for big companies, and the way AveMaria manages its infrastructure is very similar to FIN7. The last piece is the newly discovered CopyPaste group, who targeted financial entities and companies in one African country, which lead us to think that CopyPaste was associated with cybermercenaries or a training center. The links between CopyPaste and FIN7 are still very weak. It is possible that the operators of this cluster of activity were influenced by open-source publications and do not have any ties with FIN7.
All of the aforementioned groups greatly benefit from unpatched systems in corporate environments. They thus continue to use effective spearphishing campaigns in conjunction with well-known MS Office exploits generated by the framework. So far, the groups have not used any zero-days.
FIN7/Cobalt phishing documents may seem basic, but when combined with their extensive social engineering and focused targeting, they are quite successful. As with their previous fake company “Combi Security”, we are confident that they continue to create new personas for use in either targeting or recruiting under a “new” brand, “IPC”.
More information about these and related attacks is available to customers of Kaspersky Intelligence Reports. Contact: firstname.lastname@example.org
Indicators of compromise
In order to preserve the privacy of the potential victims, we stripped the targeted entities from the domain names.