Avast has launched a free decryptor for the BianLian ransomware strain to assist victims in recovering locked files without having to pay the hackers.
The decryptor, according to Avast, only works for files encrypted by a known variant of the BianLian ransomware. It may be necessary for new victims to locate the ransomware binary on their hard drive. It may be difficult to do so, however, because the ransomware deletes itself after encryption.
BianLian is a ransomware strain written in Go and compiled as a Windows 64-bit executable. Because of the nature of the Go language, many strings are directly visible in the binary, including information about the author’s PC’s directory structure.
It encrypts over 1013 file extensions on all accessible drives using the symmetric AES-256 algorithm and the CBC cipher mode. The malware encrypts the victim’s files intermittently, which speeds up the attacks at the expense of data locking strength.
If the hackers are using a new version of the malware that researchers have yet to detect, the tool will be useless.
The sources for this piece include an article in BleepingComputer.