Beware Of Weaponized EBooks That Deliver AsyncRAT

EBooks are popular, and their popularity lucrative threat actors the most, as they are widely shared digital assets that can easily circumvent security measures. 

Threat actors exploit users’ trust in seemingly harmless documents by embedding malware in eBook files or disguising malicious code as legitimate eBooks.

ASEC researchers reported that AsyncRAT distribution is via multiple file extensions (.chm, .wsf, .lnk), with threat actors hiding the malware in apparently normal document files like questionnaires.

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Weaponized EBooks Deliver AsyncRAT

Recently, a new tactic emerged where AsyncRAT is disguised as an eBook, demonstrating the evolving methods used to trick users into executing this remote access trojan.

Within the weaponized eBook package, there is a fraudulent icon indicating an LNK file containing malicious code, another TXT file with a hidden PowerShell script, compressed video files, and an actual eBook.

Upon execution, it runs RM.TXT’s hidden PowerShell script through the LNK file, which then hides the downloader malware folder and performs an obfuscated script.

Based on security products found by this script, it can begin the real malware from fake video files.

In total, three functions decompress the hidden files, register the task schedules, and execute the scripts. To run the AsyncRAT, these scripts gather the following data:-

• System information
• Load obfuscated files

The malware masquerades as legitimate processes to evade detection and uses various obfuscation techniques.

The AsyncRAT, the final payload, features anti-detection mechanisms, persistence, and data exfiltration capabilities. 

It’s distributed through various methods, including disguised files on sharing sites and phishing emails, making it a versatile and dangerous threat.

IoCs

MD5s:-

• dea45ddf6c0ae0f9f3fde1bfd53bc34f (VideoVLC_subtitles.exe)
• b8d16e9a76e9f77975a14bf4e03ac1ff (RM.TXT)
• 50005f22608e93dff1d9ed18f6be95d3 (Business Secrets from the Bible – Rabbi Daniel Lapin.LNK)
• 1ada2c6796a3486b79c5eb47fce9b19c (worldofprocure.rar)
• 21714b248ab9ca42097a7834251a7452 (NTUSER.vbs{428f9636-1254-e23e3-ada2-03427pie22}.TM.vbs)

C&C Server:-

Download URL:-

• hxxps://worldofprocure[.]com/worldofprocure.rar

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