New Global Cyber Attack on Point of Sale Systems

This post was authored by Michael Gorelik and Alon Groisman.

Over the past 8-10 weeks, Morphisec has been tracking multiple sophisticated attacks targeting Point of Sale thin clients globally.

More specifically, on the 6^th of February we identified an extremely high number of prevention events stopping Cobalt Strike backdoor execution, with some of the attacks expressly targeting Point of Sale VMWare Horizon thin clients.

Based on the initial indicators, we identified FrameworkPOS scraping malware installed on some of the thin clients, after initializing PowerShell/WMI stages that downloaded and reflectively loaded Cobalt-Strike beacon with PowerShell extension directly into the memory.

We found many indicators linking specifically to the FIN6 group (WMI/PowerShell, FrameworkPOS, lateral movement and privilege escalation), with the difference of moving from Metasploit to Cobalt-Strike). Some indicators are also tied to the EmpireMonkey group. At this point, we don’t have enough data for proper attribution.

If successful, the Cobalt Strike beacon payload gives attackers full control over the infected system and the ability to move laterally to other systems, harvest user credentials, execute code and more, all while evading advanced EDR scanning techniques.

Digging deeper into the notification and the telemetry, we identified victims across the United States, Japan and India from the finance, insurance and healthcare (diagnostic image processing) sectors, as well as additional targets globally.

Following additional retro-hunting on Virus Total, we identified multiple servers that were, and still are, delivering the Cobalt Strike beacon using the same delivery pattern and same C2 communication pattern. We have notified the customers and the legal authorities about the currently active C2 servers.

Morphisec Labs is currently still analyzing the infiltration methods (unknown); due to this we will present only partial technical information in this report. However, we believe it important to publish even a partial analysis so that enterprises are aware of, and immediately block, any access to the URLs listed below.

Technical information:

Infiltration

As stated in the introduction, the infiltration vector is yet to be determined, although after retro-hunting on VT and matching it to our known telemetry events, we believe that at least one vector is executed through HTA files that execute PowerShell scripts as part of an embedded VBScript.

Script stager

Additional hunting reveals additional scripts that lead to the same Cobalt Strike beacon. It is not known if the scripts below are part of a lateral movement or just additional examples of infiltration samples. However, at least some of them are executed through WMI which may indicate an intermediate stage. 

POWERSHELL

JAVASCRIPT

BAT

PowerShell Stager

All the various scripts are decoded to the following PowerShell pattern:

The script above decompresses an additional level of PowerShell stager (regular Gzip):

Clearly, the marked base64 encoded script represents the next stage shellcode that is either remotely injected into the existing 32 bit or into a newly created 32 bit PowerShell process (if the current PowerShell is 64bit). Some samples differentiate in the way the VirtualAlloc and CreateThread are declared.

Shellcode Stager

The injected shellcode is a regular Metasploit downloader shellcode that traverses the PEB, resolves the function names by the standard ROR 13 hash, and downloads the next stage shellcode directly into memory from the C2. The pattern of the C2 download request destination is generally URL:PORT/[a-zA-Z0-9]{4}.

It executes InternetConnectA, InternetOpenA, HttpOpenRequestA, HttpSendRequestA for the purpose of downloading the next stage.

Cobalt Strike Beacon

Morphisec observed 2 types of beacons during this campaign, the first one is a regular direct reflective loaded Cobalt Strike DLL beacon, usually XOR encoded.

The second type is a shellcode backdoor beacon with PowerShell and Mimikatz functionality.

Persistency and FrameworkPOS

In some cases, after executing the backdoors, the attackers install “WindowsHelpAssistant” task in the task scheduler. In turn, this, on login, uses rundll32.exe with System privileges to execute and export function “workerInstance” from a downloaded binary DLL “Assistant32.dll”. We also observed similar command execution as part of the HKLM Run key.

The “Assistant32.dll” is the FrameworkPOS scraper that shares similar TTPs to a previously seen FrameworkPOS used by FIN6.

The malware XOR’s (xor 0xAA) the credit card information before exfiltration through DNS tunneling.

Conclusions

These types of advanced attacks that utilize memory to evade detection solutions either by reflectively loading libraries, hollowing process memory or injecting code into new processes, are harder and harder to attribute due to the simple fact that more and more criminals are taking advantage of the strength of these evasion techniques and the weakness of runtime detection technologies to cope with such evasion. The attackers have the advantage of choosing where to execute their malicious code and when to execute it, while runtime detection solutions cannot constantly scan the memory to detect the attack precisely when it manifests without significantly impacting the performance of the process runtime.

It is important to note that Morphisec prevents these types of attacks immediately, without any prior knowledge of the attack form or techniques. The forensic information used in this analysis was captured after the attack was already prevented.

Artifacts

Domains C2s

STILL ACTIVE:

hxxp://217.12.218[.]95:22222/c7Pr 

hxxp://89.105.194[.]236:443/Xaq2

hxxp://46.166.173[.]109:443/Qq9a

hxxp://bbing.co[.]za:443/tXY7 

hxxp://47.75.151[.]154:443/ZyBG 

hxxp://185.80.233[.]166:443/qPe6 

INACTIVE:

hxxp://5.39.219[.]15:8081/JVZb
hxxp://45.247.22[.]27:4444/EzFB
hxxp://standardcertifications[.]com:8080/cArF
hxxp://34.245.88[.]113:9090/tNDV
hxxp://2.72.0[.]200/9RyX
hxxp://185.202.174[.]91:443 
hxxp://192.81.223[.]204/rr3E
hxxp://172.16.196[.]200/JSlT

hxxp://37.139.21[.]20/Orb9

hxxp://185.135.157[.]138:8080/9Par

hxxp://188.166.105[.]24/o9ZZ

hxxp://185.202.174[.]84:443/c9Fz

hxxp://35.182.31[.]181:443/jquery-3.3.1.slim.min.js

hxxp://209.126.106[.]228:443 (only 32 bit)

hxxp://172.17.3[.]2/G9fv

hxxp://104.237.131[.]29:443

hxxp://93.115.26[.]171:443

hxxp://188.166.105[.]24/cYj7

SCRIPT DOWNLOADERS:

0328fcc8229397c7bb4d0ccc958b09caa9a116b549cf59ae95b2d030ef70d54c

063060e5031ad4de170ea979e0a8e36c053904f5f4a33f147f9351328c465594

0ac9795a9eb6b374250523f29f55d07bea2c4c7077ab59c1fb38b38eca1f6f2a

0d8cd722c9cb741c68672612d9668aac59b3b116d11943fb4e010940272fe72f

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1d53bf1f98cab29509c9211e6dcf6d830ba602dd8886d1d9339c426a1ab4dbcf

1e3a4e51b9fe9d2fb94e040d3fcdb6a7874b035233ffc7ef779bd8ba01857097

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