A decryptor for the BlackByte Ransomware was released, which allows the victims of the past to restore their files for free.
As stated by a Trustwave report, researchers said BlackByte downloaded a file called ‘forest.png’ from a remote site under their control, and although the file is supposed to appear as an image file, it contains the AES encryption key used to encrypt a device.
Since BlackByte uses symmetrical AES encryption, the same key can be used to encrypt and decrypt files.
In the Trustwave discovery, BlackByte not only encrypts the AES encryption key in question downloaded and adds it to the ransom note, but the gang also used the same forest.png file for multiple victims and since the same ‘raw’ encryption key was reused, Trustwave could, in turn, use the key to build a decryption key that restores a victim’s files for free.
BlackByte victims interested in using the Trustwave decryptor are advised to download the source code from Github and compile it themselves, as Trustwave already included a default ‘forest.png’ file from which the decryption key is extracted.
It is also recommended to back up files before attempting to decrypt them, as it is possible that BlackByte rotates the encryption keys downloaded in that file.
For more information, read the original story in BleepingComputer.