Coba Ransomware (.coba Files)

Coba Ransomware uses the Salsa20 encryption algorithm. This STOP/Djvu family is one of the most popular infection!

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

About Coba Ransomware:

NameCoba Virus
File Extenstion.coba
Contact[email protected], [email protected]
FamilySTOP/Djvu Ransomware
Offline IDfTU4hYOJ0niv7WAg9utRTzxXv2TcoEvGPJhzIot1
Last seenMarch 10, 2023
AlgorithmSalsa20 encryption. If Coba 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 .coba files in the future.
RansomFrom $490 to $980 (in Bitcoins)
  1. โฎž Can delete Volume Shadow copies to make victimโ€™s attempts to restore data impossible;
  2. โฎž Adds a list of domains to HOSTS file to block access to certain security-related sites;
  3. โฎž Installs password-stealing Trojan, 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----- MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwhbzSU/RiBxX4oxDqunU 9VhWvvVRrVdcW+jVpL4otXD4yNHqD7xJLxPsoX6AsIiIio1zjCTeSgyWyswk8ay6 HzHYbhW30qp+g6Z1mz2b2B7KSNY+JX6PNWzdCCEWO1udpQ9M9jbiOg8ws59dnT7i LTeCEWV/uDEAzsBjEwESZn3Qst2n9O3BvfCBak50wLbscyk0sTej37Tc62V8E8X7 I9XY4xDsMkg/n1rYs6E9oAfhq25y2dlAAnyGa8riBgKsUkeOH/tkKfvlT2MAd8OG gPNi8unQY1M2DjGm74SYsX+ecl2AgwPpJuWT5Sbp29PBQH1n0CyJGQ6iJCmV3PXK lQIDAQAB -----END PUBLIC KEY-----
Other variants
  • Coaq Ransomware (.coaq encrypted files)
  • Cosw Ransomware (.cosw encrypted files)
  • Goba Ransomware (.goba encrypted files)
  • Coba Ransomware (.coba Files) - What is it? Keep Your Privacy Well

    Coba 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, Coba 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.

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

    .COBA 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 Coba 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.

    To get this software you need write on our e-mail:
    [email protected]

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    Indicators of Compromise(IOC)

    File NameMD5File Size
    ๐Ÿ“œ SAMPLE.EXE58556e2d969b55db9c1731ee540cb31f792064
    ๐Ÿ“œ SAMPLE.EXE40dd17b22e42cbee20ad38c566d5645a203264
    ๐Ÿ“œ SAMPLE.EXE92a65e8362924b58d5760a1f78cfb7a1724480
    ๐Ÿ“œ SAMPLE.EXEf11348aa0cb8b7950a614de54e844ee6203264
    ๐Ÿ“œ SAMPLE.EXE67dc712ff2f0250d4b74dc810a33c86b204288
    ๐Ÿ“œ SAMPLE.EXE8467eec9e8a5c74916bb63f4ecb617b9161795
    ๐Ÿ“œ SAMPLE.EXE8465c9c4664faf842462160ac3f6529c162023
    ๐Ÿ“œ SAMPLE.EXEbd473c38a3ecbf0d5b04631c3458689a158958
    ๐Ÿ“œ SAMPLE.EXE62be8d8a1a0ed29e9e0fb1a484fbf107203776
    ๐Ÿ“œ SAMPLE.EXEa29a17baf9165639588fb448d15b278e161795