HRUU Ransomware (.hruu Files)

HRUU Ransomware uses the AES-256 encryption algorithm. This STOP/Djvu family is one of the most popular infection!

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Technical details:

NameHRUU Virus
FamilySTOP/Djvu Ransomware
Note_readme.txt
File Extenstion.hruu
AlgorithmAES-256 encryption. If HRUU 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 .hruu 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 on the system, like Azorult Spyware;
DistributionThird-party downloaders, installers, peer-to-peer networks, RDP exploits, etc.,
Other variants
  • Dfwe Ransomware (.dfwe encrypted files)
  • Fdcv Ransomware (.fdcv encrypted files)
  • Fefg Ransomware (.fefg encrypted files)


  • HRUU ransomware is an example of a STOP/Djvu ransomware family. It encrypts your files with the AES-256 cipher and adds to it a .hruu extension. These files cannot be opened in any usual way. Besides the file encryption, this malware also adjusts the system settings to make its protection mechanism weaker. The alterations it does may lead to system failures in the future and make the computer harder to use regularly.

    The cipher the HRUU ransomware uses is strong enough to prevent its hacking with brute force. However, there are too many possible keys, so it is impossible to generate them all and check if one fits your case. Some of the decryptor programs that contain the already compromised keys can give you a small chance to get your files back. However, much more danger hides in the changes done by ransomware to your system configurations. Inability to install the programs or open certain websites is critical, especially if you have no important data or backup.

    Preventing ransomware injection is the best way to deal with it once and for all. The majority of HRUU virus injection cases are related to the use of hacked programs and outlaw software. Those programs are usually spread through peering networks and third-party websites, a.k.a. “software collectors”. All programs stored there are offered for free since they were hacked, and their license checking procedure was disabled. But there is no problem for the hackman to add malicious code to the program he hacks. They are paid for this, so their motivation is easy to understand.

    Encryption process

    The HRUU ransomware uses the AES-256 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 - ".hruu". Then, ransomware creates a _readme.txt file in the folder where the encrypted file is located, and goes to the next folder.

    .HRUU 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 HRUU 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.

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    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:

    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:
    
    hxxps://we.tl/t-WJa63R98Ku
    
    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:
    
    helpteam@mail.ch
    
    Reserve e-mail address to contact us:
    
    helpmanager@airmail.cc
    
    Your personal ID:
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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