A new ransomware threat has been detected called FilesLocker which is currently being offered as ransomware-as-a-service (RaaS) on a TOR malware forum. FilesLocker ransomware is not a particularly sophisticated ransomware variant, but it still poses a significant threat.

FilesLocker ransomware is a dual language ransomware variant that displays ransom notes in both Chinese and English. MalwareHunterTeam has identified a Chinese forum on TOR where it is being offered to affiliates to distribute for a cut of the ransom payments.

Unless advertised more widely, the number of affiliates that sign up may be limited, although it may prove popular. There are several features which could see the ransomware variant favored over other RaaS offerings, notably a sliding scale on commissions. The developers are offering a 60% cut of ransoms, which will increase to 75% if sufficiently high numbers of infections can be generated.

While relatively small and simple, FilesLocker ransomware still uses an RSA 2048+AES algorithm to lock files and it deletes Windows shadow copies to hamper attempts to recover files without paying the ransom. FilesLocker is also capable of file encryption in a broken network environment.

No server is required and the ransomware is effective on all Windows versions later than XP plus 32-bit and 64-bit Windows Server. Users are also able to easily monitor infections through a tracking feature which displays infections by country.

There is no free decryptor for FilesLocker ransomware. Recovery will only be possible by restoring files from backups.

While news of a new RaaS offering is never good, there has at least been some good news on the ransomware front this week, at least for some victims.

Free Decryptor Developed for GandCrab Ransomware

GandCrab ransomware is another RaaS offering that has been available since January 2018. It has been widely adopted, with many affiliates signing up to distribute the ransomware over the past 10 months.

A GandCrab ransomware decryptor was developed by Bitdefender in February that was able to unlock files encrypted by version 1.0 and v1.1 of GandCrab ransomware. The decryptor was developed after private keys were leaked online. However, it didn’t take long for v2.0 to be released, for which no free decryptor is available. There have been several further updates to GandCrab ransomware over the past few months, with v5.0 of the ransomware variant released in late September.

This week, Bitdefender has announced that after collaboration with the Romanian Police, Europol and other law enforcement agencies, a new decryption tool has been developed that allows GandCrab ransomware victims to decrypt files for free, provided they have been attacked with version 1, 4, or 5 of the ransomware.

The version can be determined by the extension used on encrypted files. V1=GDCB; v2/3=CRAB; v4=KRAB; and v5 uses a random 10-character extension.

The free GandCrab ransomware decryptor has been uploaded to the NoMoreRansom Project website. Bitdefender is currently working on a free decryptor for v2 and v3 of GandCrab ransomware.