Hackers target LNK (Windows shortcut) files to disseminate malware because they can embed malicious code that automatically executes when the shortcut is clicked. 

LNK files appear harmless but can stealthily trigger malware downloads or other malicious actions, making them an efficient initial infection vector on Windows systems.

Cybersecurity researchers at ASEC recently discovered that threat actors have been actively exploiting the weaponized Windows shortcut files to deploy the fileless “RokRat” malware.

Fileless RokRat Malware

AhnLab confirmed the ongoing distribution of RokRat malware has been targeting South Korean users, especially those related to North Korean issues, and the identified malicious LNK filenames are listed below:-

• National Information Academy 8th Integrated Course Certificate (Final).lnk
• Gate access roster 2024.lnk
• Northeast Project (US Congressional Research Service (CRS Report).lnk
• Facility list.lnk

The malicious LNK files execute PowerShell via CMD, similar to last year’s RokRAT samples. Notably, they bundle the following things within the LNK file itself to enhance the social engineering lure:-

• Legitimate documents
• Scripts
• Malicious PE payloads

When executed, the LNK file runs PowerShell to create a legitimate document decoy, followed by three files (find.bat, search.dat, viewer.dat) in the public folder. find.bat runs search.dat, which fileless executes the RokRAT backdoor payload from viewer.dat. 

RokRAT can collect user data and receive commands, exfiltrating stolen information to the attacker’s cloud servers like pCloud, Yandex, and DropBox while disguising requests as Googlebot. 

The multi-staged execution process leveraging fileless techniques aims to evade detection, reads the advisory.

RokRAT can run commands, show directories, delete startup files, gather startup/appdata/recent file listings, and harvest system and network information. 

Before being exfiltrated to attacker infrastructure in the cloud (such as pCloud masquerading as Googlebot), stolen data is staged within a temp folder. Known attacker emails are [email protected], [email protected], [email protected] and [email protected]. 

The threat actor often pursues targets associated with Korean unification, military or education sectors; organizations involved with these areas should remain extra watchful against persistent attacks of this nature.

IoCs

• b85a6b1eb7418aa5da108bc0df824fc0
• 358122718ba11b3e8bb56340dbe94f51
• 35441efd293d9c9fb4788a3f0b4f2e6b
• 68386fa9933b2dc5711dffcee0748115
• bd07b927bb765ccfc94fadbc912b0226
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• 3114a3d092e269128f72cfd34812ddc8
• bd98fe95107ed54df3c809d7925f2d2c

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