TA416 Increases Operational Tempo Against European Governments as Conflict in Ukraine Escalates

Close analysis of the delivered payloads and legitimate resources retrieved from URLs by the first stage malware dropper reveals that TA416 is once again using an updated version of PlugX malware to target their victims.
Historically, the group has relied on a variety of legitimate antivirus files, including the Avast file resource wsc_proxy.exe, to begin the process of DLL search order hijacking that results in PlugX malware installation.
In the January 2022 campaigns, TA416 used the PE file potplayermini.exe to initiate DLL search order hijacking.
This is a legitimate executable file that is part of the publicly available media player Daum PotPlayer 1.5.29825, which Mandiant has previously documented as being susceptible to search order hijacking since at least 2016.
Numerous Chinese APT groups, which are not directly correlated to TA416, have utilized it since that time. This campaign leveraged the vulnerability of potplayermini.exe to load the file PotPlayer.dll which contains an obfuscated launcher that in turn executes the file PotPlayerDB.dat.
The file DocConvDll.dll has also intermittently been used as a loader of the PlugX DAT configuration files.
For those that are familiar with TA416’s historic tactics, techniques, and procedures (TTPs), this is highly similar to the Trident Loader method which the group used to install PlugX in previous campaigns.

While PotPlayerDB.dat is a variant of PlugX malware, TA416 has updated the payload by changing both its encoding method and expanding the payload’s configuration capabilities.
Historically, TA416 relied on the DLL launcher to decode the PlugX payload utilizing an XOR key included at the offset 0 within the PlugX DAT configuration file.
In this case, TA416 has abandoned that approach in favor of something with less dependencies that is more convoluted.
The latest version contains obfuscation to thwart analysis.
One of the main ways it does this is by resolving API functions during runtime. Generally, malware loads a DLL, iterates over the set of exports of the DLL and hashes the string, looking for a matching hash.
This iteration of PlugX does standard API hashing, but only to resolve the address of the functions GetProcAddress as well as LoadLibrary.

In addition to this obfuscation attempt, most of the functions that contain the “business logic” of the malware are obfuscated with a state machine.
At a high level this obscures the order of which blocks are executed within a function. It does this by maintaining a state variable with many comparisons in the function.
After each block, the state variable is modified to whatever the subsequent block should be, making analysis more difficult. This sample further implements anti-analysis techniques via the malware’s design.
After every iteration of the state machine, the malware sample will modify the state with a XOR operation.
This makes it difficult to analyze as the states are not hardcoded as the result of a function.

Sign Up For Threat Alerts

Loading...
Threats Icon

Aug 16, 2022

LockBit Ransomware Abuses Legitimate Windows Defender Utility

The LockBit ransomware-as-a-service was identified using a legitimate Windows Defender command line utility to decrypt...

Threats Icon

Aug 14, 2022

US Cert Alert – Zeppelin Ransomware

The Federal Bureau of Investigation (FBI) and the Cybersecurity and Infrastructure Security Agency (CISA) are...

Threats Icon

Aug 11, 2022

Cisco Talos shares insights related to recent...

Initial access to the Cisco VPN was achieved via the successful compromise of a Cisco...

Threats Icon

Aug 11, 2022

Andariel deploys DTrack and Maui ransomware

The CISA published an alert, entitled, "North Korean State-Sponsored Cyber Actors Use Maui Ransomware To...

Threats Icon

Aug 09, 2022

Albanian Government Organizations Targeted By Possible Iranian...

Mandiant identified the ROADSWEEP ransomware family and a Telegram persona which targeted the Albanian government...

Threats Icon

Aug 08, 2022

BumbleBee Roasts Its Way to Domain Admin

Threat actors used BumbleBee as the initial access vector. BumbleBee is a malware loader that...

Threats Icon

Aug 08, 2022

RapperBot – new evolving malware

FortiGuard Labs has been tracking a rapidly evolving IoT malware family known as "RapperBot". This...

Threats Icon

Aug 04, 2022

Google Drive And Dropbox Used By APT29...

Cloaked Ursa (aka: APT29) has been targeting governmental entities in several countries with spear-phishing campaigns...

Threats Icon

Aug 03, 2022

Manjusaka: A Chinese sibling of Sliver and...

Cisco Talos recently discovered a new attack framework called "Manjusaka" being used in the wild...

Threats Icon

Aug 03, 2022

macOS Targeted With The CloudMensis Multi-Staged Malware

ESET researchers discovered a previously unknown macOS backdoor that spies on users of the compromised...

Threats Icon

Aug 01, 2022

Attackers Target Ukraine With GoMet Backdoor

Since the Russian invasion of Ukraine began, Ukrainians have been under a nearly constant barrage...

Threats Icon

Jul 31, 2022

Untangling KNOTWEED: European private-sector offensive actor using...

The Microsoft Threat Intelligence Center (MSTIC) and the Microsoft Security Response Center (MSRC) found a...

Threats Icon

Jul 31, 2022

Untangling KNOTWEED: European private-sector offensive actor using...

The Microsoft Threat Intelligence Center (MSTIC) and the Microsoft Security Response Center (MSRC) found a...

Threats Icon

Jul 26, 2022

EvilNum Targets Cryptocurrency, Forex, Commodities

Proofpoint Threat Research observed the group Proofpoint calls TA4563 targeting various European financial and investment...

Threats Icon

Jul 25, 2022

Lightning Framework: New Undetected “Swiss Army Knife”...

Lightning is a previously undocumented and undetected Linux threat. Lightning is a modular framework we...