New x1881 CryptoMix Ransomware Variant Released

New x1881 CryptoMix Ransomware Variant Released

By | October 16th, 2017
No Comments on New x1881 CryptoMix Ransomware Variant Released

MalwareHunterTeam discovered a new variant of the CryptoMix ransomware

that is appending the .x1881 extension to encrypted file names. It's has

been about three weeks since a new CryptoMix variant was released, which is

quite long for this family of ransomware.


While the encryption methods stay the same in this variant, there have been some slight differences. The ransom note is still named _HELP_INSTRUCTION.TXT, but now uses the emails for a victim to contact for payment information.

x1881 CryptoMix Ransom Note
x1881  CryptoMix Ransom Note

The next noticeable change is the extension appended to encrypted files. With this version, when a file is encrypted by the ransomware, it will modify the filename and then append the .x1881 extension to encrypted file’s name. For example, a test file encrypted by this variant has an encrypted file name of 0D0A516824060636C21EC8BC280FEA12.x1881.

Folder of Encrypted x1881 Files
Folder of Encrypted x1881 Files

This variant also contains 11 public RSA-1024 encryption keys that will be used to to encrypt the AES key used to encrypt a victim’s files. This allows the ransomware to work completely offline with no network communication. This variant’s 11 public RSA keys are the same as the previous Shark Cryptomix Ransomware variant.

In order to protect yourself from the x1881 variant of CryptoMix , or from any ransomware, it is important that you use good computing habits and security software. First and foremost, you should always have a reliable and tested backup of your data that can be restored in the case of an emergency, such as a ransomware attack.

You should also have security software that contains behavioral detections such as Emsisoft Anti-Malware or Malwarebytes.  Regardless of the security software you use, make sure it contains behavioral detections so you do not have to rely on signatures or heuristics.


Nisheeth Bhakuni