Btos Virus Ransomware (.btos File)

Btos Virus is 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.

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About Btos Ransomware:

NameBtos Virus
File Extension.btos
Contact[email protected], [email protected]
FamilySTOP/Djvu Ransomware
Offline ID8p2Go5ZmkbFk0DF2oJ6E8vGEogpBqqaGCWjto1t1
Last seenDecember 17, 2022
AlgorithmSalsa20 encryption. If Btos 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 .btos files in the future.
RansomFrom $490 to $980 (in Bitcoins)
  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----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2WGo+MCJG9I8Lre0I/T5 sfqPRJrCtTzfUXF0FjPEKhanNQiJw+EQgBU271jzSh1f7wk4ayYWtBAYHjqtzsQw yl5YXvU0LqZbmnfvZX76vC2+jJVu9PNpImVquYPPRNgons3BTKJT+BiqqO/LzXFw h3iyROlCo1vwmH+hX6MZoMAVWhme50Cs7uKFiNiIwpVyYc9hgXHkVGJC6aWwwTFU cYd6AM1cjjjw7EURP54jjZtHQD9KKv2NHMYVt2jf+mCIXN1v6F2s56bwM+moWdG3 uMZpwo15UmBQtf+wDqAI+yYIpb/1y80JFinAWrCO4DGUzQ/vlrzSwjN5fmX7clnP 6wIDAQAB -----END PUBLIC KEY-----
Other variants
  • Btnw Ransomware (.btnw encrypted files)
  • Matu Ransomware (.matu encrypted files)
  • Maos Ransomware (.maos encrypted files)
  • Btos Virus Ransomware (.btos) File - How does it work?

    What is Btos ransomware?

    Btos ransomware busts the myth that you will never get a virus until you try to launch something dubious. This invades your system, encrypts the files, and then asks you to pay money to get your files back. Besides the fact that you cannot get your files, it also makes your security tools inaccessible.

    The encryption this malware uses to cipher your files is pretty strong, and it becomes even more assertive because the decryption key is kept on the remote server. Unfortunately, the fraudsters control this server, and the only way to get the key from this server is to pay the ransom (about $1000). Other forms of file decryption may help you, but the chances are pretty low, as statistics say.

    Besides the ciphering, Btos ransomware also does some damage to other system elements. Nothing severe, but these changes are making your computer difficult to use. Inability to open specific sites, failures at the attempt to install antivirus programs - even some of the networking elements inside other programs may be corrupted. It is better to revert all these alterations as soon as possible.

    Btos ransomware is usually spread through third-party websites that are offering to get some paid programs for free. Other parts of these sites are the so-called hack tool - cheat engines, keygens, and other things used to change the gaming process. Implementing the malware into these programs is effortless: people who create it have full access to the executable code. Adding the virus is just a question of who pays the hacker means more.

    Encryption process

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

    .BTOS 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 Btos 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:


    Don't worry, you can return all your files!
    All your files like pictures, 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:
    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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    🔗 HowToFix.Guide: How To Decrypt .btos Files?

    Indicators of Compromise(IOC)

    File NameMD5File Size
    📜 SAMPLE.EXE15a0e10737f8130015002c0ff4d8628e750080