Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

ABTV

1/2/2020
09:25 AM
Larry Loeb
Larry Loeb
Larry Loeb
50%
50%

Fortinet Finds Loader Uses Updated Version of Backdoor

Security firm Fortinet has found traces of how the financially motivated FIN7 group manages to keep on delivering the Carbanak backdoor malware.

When malware has been around for a while, its authors are faced with the need for its maintenance if they want it to continue to succeed in their criminal activity.

Security firm Fortinet has found traces of how the financially motivated FIN7 group does this kind of maintenance on delivering the Carbanak backdoor malware.

FireEye has already looked at one way that FIN7 does this with its BOOSTWRITE loader tool. Fortinet found that the predecessor BIOLOAD tool is a loader as well, but with a different and singular payload. BIOLOAD is not as easily detected as BOOSTWRITE but has the same end effect.

The malware subverts the normal way that Windows will load a Dynamic Linked Library (DLL), by a technique known as DLL search order hijacking (or binary planting). In this case, the attackers use FaceFodUninstaller.exe. This exists on a clean OS installation starting from Windows 10 RS4 (1803) at the "%WINDR%\System32\WinBioPlugIns" folder. The executable is also dependent on winbio.dll, which is usually found in the parent directory ("%WINDR%\System32").

The uninstaller program is started by a built-in scheduled task named FODCleanupTask, which minimizes the attacker's footprint on the machine and therefore reduces the chances of detection even further.\r\nBIOLOAD has the encrypted payload DLL embedded in it. Unlike BOOSTWRITE, it does not support multiple payloads. Decrypting the payload is done by a simple XOR decryption. This is a key point, because it implies that BIOLOAD is tailor-made for every machine it infects. It will use the machine name to derive the decryption key. This means that it does not need to access a remote server in order to fetch the key.

The attacker places the resultant malicious WinBio.dll in the "\System32\WinBioPlugIns" folder, which is home of the legitimate DLL "winbio".

Fortinet says that, "The samples [that they found] target a 64-bit OS and were compiled in March and July of 2019. BOOSTWRITE targets 32-bit machines and was compiled (and signed) in May 2019."

Fortinet also found that BIOLOAD contained newer builds of the Carbanak backdoor than BOOSTWRITE. They were dated January and April of 2019, according to their timestamps. This version checks to see if another Anti-Virus (AV) is running on the machine, besides Kaspersky, AVG and TrendMicro. The result, however, has no effect on the operations of the backdoor.

BIOLOAD has the characteristic of being the first public case of FaceFodUninstaller.exe being abused as host process by a threat actor.

Also, BIOLOAD shows that the attackers are specifically building infections for each targeted machine as well as somehow obtaining the needed administrative permissions to deploy it. This implies that the group needs to gather other critical information about its targets' networks in order to carry out the attack.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Edge-DRsplash-10-edge-articles
I Smell a RAT! New Cybersecurity Threats for the Crypto Industry
David Trepp, Partner, IT Assurance with accounting and advisory firm BPM LLP,  7/9/2021
News
Attacks on Kaseya Servers Led to Ransomware in Less Than 2 Hours
Robert Lemos, Contributing Writer,  7/7/2021
Commentary
It's in the Game (but It Shouldn't Be)
Tal Memran, Cybersecurity Expert, CYE,  7/9/2021
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
Enterprise Cybersecurity Plans in a Post-Pandemic World
Download the Enterprise Cybersecurity Plans in a Post-Pandemic World report to understand how security leaders are maintaining pace with pandemic-related challenges, and where there is room for improvement.
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2018-20686
PUBLISHED: 2021-09-17
** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: This candidate was withdrawn by its CNA. Further investigation showed that it was not a security issue. Notes: none.
CVE-2021-38402
PUBLISHED: 2021-09-17
Delta Electronic DOPSoft 2 (Version 2.00.07 and prior) lacks proper validation of user-supplied data when parsing specific project files. This could lead to a stack-based buffer overflow while trying to copy to a buffer during font string handling. An attacker could leverage this vulnerability to ex...
CVE-2021-38404
PUBLISHED: 2021-09-17
Delta Electronic DOPSoft 2 (Version 2.00.07 and prior) lacks proper validation of user-supplied data when parsing specific project files. This could result in a heap-based buffer overflow. An attacker could leverage this vulnerability to execute code in the context of the current process.
CVE-2021-38406
PUBLISHED: 2021-09-17
Delta Electronic DOPSoft 2 (Version 2.00.07 and prior) lacks proper validation of user-supplied data when parsing specific project files. This could result in multiple out-of-bounds write instances. An attacker could leverage this vulnerability to execute code in the context of the current process.
CVE-2021-41326
PUBLISHED: 2021-09-17
In MISP before 2.4.148, app/Lib/Export/OpendataExport.php mishandles parameter data that is used in a shell_exec call.