GUJD Ransomware (.gujd File Extension)

What is Gujd?

Ransomware manifests in numerous forms, with Gujd ransomware representing a particularly insidious variant. This virus specifically targets individual users, encrypting any accessible files on the infected device. Moreover, it incapacitates your security defenses and significantly complicates networking activities.

Recovering the encrypted files is an arduous task. The malware employs the formidable Salsa20 encryption algorithm, rendering brute-force hacking attempts futile. Subsequently, it transfers the decryption keys to a command server under cybercriminal control. These adversaries will only relinquish the decryption key upon receiving a ransom payment or if they are apprehended by law enforcement.

The distribution of Gujd ransomware follows conventional pathways common to many viruses. Software obtained from peer-to-peer networks (such as eMule or ThePirateBay), often touted as "free," serves as an ideal vector for ransomware dissemination. Users are likely to dismiss security warnings during download and installation, leaving them oblivious to the antivirus's incapacitation following the attack.

Gujd Encryption process

The Gujd uses the Salsa20 encryption algorithm. That is not the strongest method, but it still provides an overwhelming amount of possible decryption keys. To brute force the 78-digit number of keys, you need 3.5 unvigintillion years (1*10^65), even if you use the most powerful regular PC. Quantum computers can show a bit better results, but it is still too slow to get your files back while you are alive.

The exact algorithm of encryption is next: malware scans each folder for the files it is able to encrypt. Then, when it finds the target, it makes a copy of your file, removes the original one, encrypts the copy and leaves it instead of the removed original. Such a procedure is done to prevent the situation when you have already opened the file, so ransomware is not able to read it because of the Windows restrictions. To each encrypted copy, the virus adds the specific extension - ".gujd". Then, ransomware creates a _readme.txt file in the folder where the encrypted file is located, and goes to the next folder.

Such an encryption method can be exploited for file recovery. Since the original file is deleted, you may try to recover it using the file recovery tools. The less time is passed - the bigger the chance to get your files back, so hurry up!

Another specific moment that can help you to use the files even after the encryption is the fact that Gujd ransomware encrypts only the first 150KB of each file. Hence, you can try to run a big file, such as video or music, without the encryption. Similar feature also works with other ransomware families - Dharma, Conti and Makop encrypt the same 150KB.

Gujd note:

Ransom note is the same for the whole STOP/DJVU family. In fact, it is one of the main signs of to which family the certain ransomware belongs. Here is the typical note for STOP/Djvu family:

Indicators of Compromise(IOC)