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NOSU Ransomware (.nosu File Extension)

NOSU a strain within the STOP/Djvu Ransomware family, employing the Salsa20 encryption algorithm to encrypt files on compromised systems. Victims are coerced into paying a ransom ranging from $490 to $980 in Bitcoins for the decryption key.

You may be interested in taking a look at our other antivirus tools:
Trojan Killer, and Online Virus Scanner.

About Nosu:


NameNosu Virus
Version0197
File Extension.nosu
Contact[email protected], [email protected]
FamilySTOP/Djvu Ransomware
Note_readme.txt
Offline IDv06YHbhNNHIA4FoWgk8Exu5sTjk6CwEDVSQZ35t1
Last seenJuly 25, 2022
AlgorithmSalsa20 encryption. If Nosu cannot establish a connection to crooks server before starting the encryption process, it uses the offline key. This key is the same for all victims(!), making it possible to decrypt .nosu files in the future.
RansomFrom $490 to $980 (in Bitcoins)
Damage
  1. ⮞ Can delete Volume Shadow copies to make victim’s attempts to restore data impossible;
  2. ⮞ Adds a list of domains to HOSTS file to block access to certain security-related sites;
  3. ⮞ Installs password-stealing trojan virus, like Redline Stealer, Vidar Stealer, Smokeloader, Azorult and others;
DistributionThird-party downloaders, installers, peer-to-peer networks, RDP exploits, etc.,
RSA Public Key-----BEGIN PUBLIC KEY----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqrsW7iLE1k5DWOkJKaJ6 Hk6aoZVw0BzAEL4A/ycucsgfn8NF3X1Lswiq580V/GfVu52ZFu0wInrgBGmqcPsK 5I6qQkB92t/9AzzmSdyOxbiq88EFjpkrE9KLVltb5KWHHVXzdBSXtNdo1wA1YLFD mo+dHqe3jX8zBJ9g+SqdIgONg+60tSuyOTP85uG4/1LkQBB+6FIc0e4FImwPaZ1u gtOeTYNNcWGWCBH7IDQpQ8bg2PmpmkKN0sCNtVOTeQBUulOuMw3t8/NhlZLbbq80 lwh7skSYKfKpdwpyWs0tZbxYfZ0YNXm/alhlXORAPlMZ2Q02GLSHDl+54NaQ8w5L fQIDAQAB -----END PUBLIC KEY-----
Other variants
  • Piny Ransomware (.piny encrypted files)
  • Nbes Ransomware (.nbes encrypted files)
  • Mkos Ransomware (.mkos encrypted files)
  • NOSU Virus Removal Tool

    What is Nosu?

    Nosu ransomware is part of the STOP/Djvu ransomware family, which typically targets individuals. This focus is evident not only through statistics but also by examining the specific distribution methods and actions this malware undertakes post-infection. It employs the Salsa20 cipher for file encryption, a method that is effectively impervious to cracking. All decryption keys are stored on a remote server under the control of cybercriminals.

    This malware enacts several modifications to system configurations, notably disabling Microsoft Defender and hindering the execution of anti-malware software installation files. These adjustments are facilitated through Group Policies, a Windows interface that provides access to advanced system settings.

    Nosu ransomware often proliferates via questionable websites that offer paid programs for free. These sites attract visitors with the allure of bypassing payment, providing hacked versions of software that circumvent licensing requirements. During the hacking of the source code, perpetrators can seamlessly integrate any form of malware. The specific type of malware incorporated may vary based on the payment made for its distribution.

    Alternative vectors for the spread of Nosu ransomware include so-called hack tools. Applications such as keygens, Windows activation utilities, cheat engines, and similar tools serve as ideal conduits for malware. Utilizing these tools not only exposes users to the risk of Nosu infection but also poses the threat of legal repercussions for the use of unlicensed software.

    Nosu Encryption process

    The Nosu 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 - ".nosu". Then, ransomware creates a _readme.txt file in the folder where the encrypted file is located, and goes to the next folder.

    .NOSU Files

    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 Nosu 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.

    Nosu 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:

    ATTENTION!

    Don't worry, you can return all your files!
    All your files like photos, databases, documents and other important are encrypted with strongest encryption and unique key.
    The only method of recovering files is to purchase decrypt tool and unique key for you.
    This software will decrypt all your encrypted files.
    What guarantees you have?
    You can send one of your encrypted file from your PC and we decrypt it for free.
    But we can decrypt only 1 file for free. File must not contain valuable information.
    You can get and look video overview decrypt tool:
    https://we.tl/t-Oc0xgfzC7q
    Price of private key and decrypt software is $980.
    Discount 50% available if you contact us first 72 hours, that's price for you is $490.
    Please note that you'll never restore your data without payment.
    Check your e-mail "Spam" or "Junk" folder if you don't get answer more than 6 hours.


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    Indicators of Compromise(IOC)

    File NameMD5File Size
    📜 SAMPLE.EXE75d60f549c9d36aa88f78618a0ab9039859136