Malware lab, Emsisoft has released a free decryptor tool on June 4 enabling victims to recover files encrypted by Tycoon (originally known as RedRum) ransomware attacks without needing to pay the ransom.
Researchers from BlackBerry’s security unit first discovered the ransomware. Tycoon uses a Java file format to make it more difficult to detect before deploying its payload that encrypts the files.
Brett Callow, threat analyst of Emsisoft, said:
“Tycoon is a Java-based, human-operated ransomware that appears to specifically target smaller enterprises and is typically deployed via an attack on RDP. Java-based ransomware is unusual, but certainly not unique. Microsoft warned about another Java-based ransomware strain, PonyFinal, last month.”
Callow also clarified some of the limitations of the free tool “Emsisoft Decryptor for RedRum”:
“(…) the tool only works for files encrypted by the original Tycoon variant, not for files encrypted by any subsequent variants. This means it will work for files that have a .RedRum extension, but not for files with .grinch or .thanos extension. Unfortunately, the only way to recover files with those latter extensions is to pay the ransom.”
BlackBerry’s researchers noted that Tycoon ransomware can run on both Windows and Linux computers, employing the same technique of asking for cryptocurrency payments.
Latest findings reveals that Tycoon infections mostly target educational institutions and software houses.
Researchers from BlackBerry believes that the actual number of infections “is likely far higher.” They also warned that newer versions of Tycoon ransomware have been improving its attack power.
Previously, decryption tools could be used to recover files for multiple victims, however it is no longer possible.