Pierluigi Paganini October 11, 2019

Good news for the victims of the Nemty Ransomware, security researchers have released a free decryptor that could be used to recover files.

I have great news for the victims of the recently discovered Nemty Ransomware, security researchers have released a free decryptor tool that could be used to recover files.

In mid-August, the Nemty ransomware appeared in the threat landscape, the name of the ransomware comes after the extension it adds to the encrypted file names. The malicious code also deletes their shadow copies to make in impossible any recovery procedure.

Below the ransom note dropped by the Nemty ransomware after the encryption process is completed. Attackers demand the payment of a 0.09981 BTC ransom (roughly $1,000) through a portal hosted on the Tor network.

Crooks used multiple attack vectors to distribute the ransomware, according to the popular malware researcher Vitali Kremez, the ransomware is mainly dropped via compromised remote desktop connections.

Now researchers from the security firm Tesorion have developed a decryptor tool that works on Nemty versions 1.4 and 1.6, they also announced a working tool for version 1.5.

The security form is also working with Europol to get its decryptors included in their NoMoreRansom project.

“As 1.6 is the most recent version of the two, we have been focussing our efforts on this version first. We now have a working decryptor for version 1.6. Please contact Tesorion CSIRT to obtain our decryptor for free if you are a victim of Nemty 1.6. We are also finishing our decryptor for Nemty 1.5 and expect to release it soon as well.” reads the post published by Tesorion.

The decryptor currently supports only a limited number of file extensions, anyway, researchers are working to improve it and support other file types.

Tesorion is not allowing victims to generate the decryption keys with their client, instead, it is allowing victims to retrieve the decryption key by generating it on its own servers.

Victims can contact the Tesorion CSIRT and request help with the Nemty Ransomware, in turn the company will then send a link to the decryptor that will allow you to decrypt the files.

“Tesorion told BleepingComputer they went this route in order to prevent the ransomware developers from analyzing the decryptor and learning the weakness in their algorithm.” reported BleepingComputer.

Victims can upload their files on the Tesorion serves that will use it to calculate the decryption key, then the key is sent back to the victims that can load is in the decryptor.

Pierluigi Paganini

(SecurityAffairs – Nemty ransomware, malware)

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