Meet Rook Ransomware

Description

FortiGuard Labs is aware of a recently reported ransomware "Rook". According to a publicly available report, Rook appears to be based on the leaked Babuk ransomware source code. One of the Rook's victims is a financial institution in Kazakhstan which the ransomware gang stole more than 1,000 GB worth of data.

Why is this Significant?

This is significant because Rook is one of the recent ransomware gangs that joined the already crowded ransomware landscape. The ransomware reportedly infected a financial institution in Kazakhstan and stole more than 1,000 GB worth of data.

What is Rook Ransomware?

Rook ransomware is reported to be based on the leaked Babuk source code and was first discovered in the wild at the end of November 2021. Files encrypted by Rook ransomware typically has ".rook" file extension, however the earlier version of Rook is said to use ".tower" file extension instead. The ransomware leaves a ransom note in HowToRestoreYourFiles.txt, which the victim is instructed to contact the Rook gang by either accessing the Rook's Tor web site or emailing the threat actor. The ransom note warns the victim that the private key to decrypt the encrypted files will be destroyed if a security vendor or law enforcement agency joins the negotiation.

How is Rook Ransomware Delivered?

Rook ransomware is reported to have been delivered via Cobalt Strike or untrustworthy Torrent downloads.

What is the Status of Coverage?

FortiGuard Labs provide the following AV coverage against Rook ransomware:

W32/Filecoder_Sodinokibi.A!tr.ransom

Appendix

New Rook Ransomware Feeds Off the Code of Babuk (SentinelOne)