Nood Virus Ransomware (.nood File)

What is Nood ransomware?

Nood ransomware attack is a pretty unwanted case. It ciphers the files and then asks you to pay the ransom in Bitcoins - about $1000 in equivalent. Money laundering is the single target of cybercriminals who spread this malware - they do not hunt for personal information or other confidential data.

The cipher this virus uses is impossible to decrypt. Not only the type of encryption makes this process so hard - the decryption keys are stored on the remote server, controlled by crooks. Brute force or any other way to find the decryption key is useless because of the enormous amount of total possible keys (2*10^78).

Nood malware also changes several vital parameters in your computer, making it harder to find the decryption solution. Blocking the running of installation files, preventing access to anti-malware forums and sites are the most harmful things it does. Meanwhile, several changes in other system configurations will surely make your PC harder to use.

It is essential to know how you got this - at least to prevent the repeating malware injection. This virus is generally spread through the websites that distribute the “free” versions of well-known programs. For example, installing a hacked Photoshop may look like it carries nothing dangerous. Still, you never know if the user who fell the program added a virus into the application’s executable code.

Encryption process

The Nood ransomware 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 - ".nood". 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 Nood 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.

Ransom note: _readme.txt

Ransom note is the same for the whole ransomware 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:

External Links:

🔗 HowToFix.Guide: How To Decrypt .nood Files?

Indicators of Compromise(IOC)

File Name	MD5	File Size
📜 SAMPLE.EXE	373dbc2f5f92e4b275e9a6716b432d98	775168
📜 SAMPLE.EXE	887ea5f3d717508b4c6349ca84dbdba8	675198
📜 SAMPLE.EXE	5ff0ef9fa269b54d2b7b08f7854d880c	695296
📜 SAMPLE.EXE	36d66e93b377ab343f73e8f9df0d9655	995328