Cybersecurity researchers at ASEC have uncovered a sophisticated campaign where hackers exploit weaponized Windows shortcut (LNK) files to deploy the fileless RokRat malware. These seemingly harmless LNK files can execute malicious code automatically when clicked, making them an effective infection vector on Windows systems. The attack primarily targets South Korean users, especially those involved in issues related to North Korea. Notable malicious LNK filenames include “National Information Academy 8th Integrated Course Certificate (Final).lnk” and “Gate access roster 2024.lnk.”
When executed, these LNK files run PowerShell commands to create legitimate document decoys and execute a series of scripts that ultimately deploy the RokRat backdoor payload. This malware operates in a fileless manner to evade detection, executing commands, collecting user data, and exfiltrating stolen information to cloud servers like pCloud, Yandex, and DropBox, while disguising these actions as Googlebot requests. The collected data is staged within a temporary folder before being sent to the attacker’s infrastructure.
The multi-staged execution process includes creating files such as find.bat, search.dat, and viewer.dat in the public folder. The find.bat script runs search.dat, which filelessly executes RokRat from viewer.dat. RokRat’s capabilities include running commands, showing directories, deleting startup files, and harvesting system and network information.
Organizations in the Korean unification, military, and education sectors should remain particularly vigilant against this threat. Mitigation steps include monitoring for known Indicators of Compromise (IoCs) and strengthening defenses against LNK file exploits. Some known IoCs include file hashes like b85a6b1eb7418aa5da108bc0df824fc0 and 68386fa9933b2dc5711dffcee0748115. Immediate action is recommended to protect against these sophisticated and persistent attacks.
