Security researchers from Malwarebytes detected Scarab ransomware variant distributed through RDP and used AES algorithm for encryption. The Scarabey variant is written in Delphi and it is identical to Scarab version the only change is the addresses of code and memory data references.
The popular version of the Scarab Ransomware distributed by a Necurs botnet and it is written in C. Scarabey found targetting Russian users and is designed same as like any other ransomware demanding Bitcoin.
The main difference between them is the ransom note, with Scarab it is written in English and on Scarabey it is written in Russian. Scarab uses to warn the users to make payment soon else the price will increase, on the other hand, Scarabey warns more and more files will be encrypted.
Researchers said There is no backdoor or remote access code in scarab or its variants, which makes the threat of deleting files on victim’s computer impossible.
Execution Flow – Scarabey
It checks with the parameters before executing to ensure this is the first run, also it makes sure there is key process is running. If any key process found it kills the process to avoid having the file locked.
Encryption loops called multiple sections in the code, but the main loop performs the majority of the encryption. It goes through all the folders if the file is not .exe or .dll it encrypts and changes to the .scarab extension.
It doesn’t use crypto APIs instead it uses AES algorithm for encryption. Malwarebytes provided technical analysis of the ransomware.
“The key used to encrypt changes from file to file. Meaning that two files with identical content will be different after encryption. Essentially what happens is that there is an initial key and many subkeys are derived from that key.
If just a single encryption key was used for all of the files, you would be able to capture the memory at any point in the encryption process, save the key, and use it to decrypt all of the files on your hard drive. Unfortunately, because of this key cycling that Scarab performs, it makes decryption of the files likely impossible.” researchers said.
Once the disk drive encryption completed it calls to the enumeration functions to locate the network drives and folders.
Source : GBHackers