QUAL Virus File — How to Decrypt & Remove Ransomware

The Qual virus, also known as a ransomware infection, belongs to the STOP/DJVU family. This malware is known for its malicious file encryption capabilities. When the Qual virus gets into a computer system, it scans the system for files like photos, videos, documents, and more. It modifies the file structure and appends the “.qual” extension to each file, making them unusable without the decryption key.

Qual Virus Overview

Qual

🤔 Qual virus belongs to ransomware that originates from the DJVU/STOP family. Its main target is to lock files that are important to you. Then, this ransomware asks its victims to pay the ransom – ($499 – $999) in Bitcoin.

The Qual virus is a malicious program that encrypts your files and coerces you into paying for their restoration. This ransomware encrypts different file types. ciphered files become identifiable by a distinct “.qual” extension. As a result, the affected files become inaccessible and unusable.

Subsequently, the ransomware asks for a ransom payment in Bitcoin from the victims, that ranges from $499 to $999, depending on the time passed after the attack. In all cases, a ransom text file is named as “_readme.txt“.

Qual Ransomware operates by Salsa20 encryption algorithms to cipher the files. Since Qual virus utilizes such a robust encryption method, it becomes pretty hard, if not impossible, to find the decryption key without cooperating with the attackers.

Once the files are encrypted, the Qual virus displays a ransom note to the victim, demanding a ransom payment in exchange for the decryption key. The ransom note provides instructions on the ways of making the payment and often includes threats of data loss or ransom amounts surge if the demands are not met within a specified timeframe.

I have compiled a comprehensive list of the solutions, advice, and practices to remove the Qual ransomware and recover access to your files. There are cases when it may be possible to restore your files, but sometimes, it may be impossible.

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📌 Important Note!

It is crucial to note that paying off the bill does not guarantee the successful recovery of your files. The scoundrels behind the Qual virus are known for their untrustworthiness. There were the cases where victims have paid the ransom, only to be denied by the cybercriminals with the decryption key provision.

Qual employs a unique key for each victim, with one exception:

If Qual fails to connect the command and control server (C&C) before starting the encryption process, it uses offline keys. An offline key is the same for all users, allowing for the decryption of files encrypted by the ransomware.

The Qual virus is highly similar to other DJVU ransomware samples such as Sarut, Watz, Waqa, and Veza. This virus encrypts a wide range of common file types and appends its distinct “.qual” extension to all files. For instance, a file named “1.jpg” would be altered to “1.jpg.qual” and “2.png” to “2.png.qual“.

Upon successful encryption, the virus spawns a special text file named “_readme.txt” and places it in every folder containing the encrypted files. It also adds this file to the desktop, so the victim will not miss the attack even without opening folders.

The image below provides a visual representation of files with the “qual” extension:

Encrypted Files by STOP/DJVU Ransomware

Name	Qual Virus
Ransomware family¹	DJVU/STOP² ransomware
Extension	.qual
Ransomware note	_readme.txt
Ransom	From $499 to $999 (in Bitcoins)
Contact	[email protected], [email protected]
Detection	Trojan:Win32/Tnega!MSR Removal, Win32:Adware-DNA [Adw] Virus Removal, Win32:Secat [Trj] Virus Removal
Symptoms	Disables Volume Shadow copies, making victim’s attempts to restore data futile; Installs password-stealing Trojan on the system, like Vidar Stealer or RedLine Stealer; Successfully installs a SmokeLoader backdoor for remote access; Updates the HOSTS file with a list of domains to block access to certain security-related sites; Implements encryption to lock most of your files (photos, videos, documents) and adds a particular “.qual” extension;
Fix Tool	To remove possible malware infections, scan your PC: 6-day free trial available.

This message asking payment is for restore files via decryption key:

_readme.txt (STOP/DJVU Ransomware) – The frightening notification insisting users to pay the ransom to decrypt the encrypted data contains these annoying warnings.

Qual ransomware arrives as a set of procedures that are used to execute certain functions on a victim’s computer. One of the initial processes being launched is winupdate.exe, a sneaky process that displays a fake Windows update pop-up during the attack. This is meant to convince the victim that their PC has become slow because of a Windows update.

Simultaneously, the ransomware runs another process (usually named by four random characters) which starts scanning the disk for target files and encrypting them. Next, the ransomware removes Volume Shadow Copies from the disk through the following CMD command:

vssadmin.exe Delete Shadows /All /Quiet

Once removed, it becomes impossible to restore the previous computer state using System Restore Points. The concern is, ransomware operators are eliminating any built-in Windows techniques that could help the victim to recover files for free. In addition, the rascals modify the Windows HOSTS file by appending a list of domains to it and redirecting them to the localhost IP. As a result, the victim will face a DNS_PROBE_FINISHED_NXDOMAIN error when trying to access one of the blocked websites.

It has come to our attention that ransomware tries to block websites that publish various how-to guides for computer users. It is obvious that by hindering specific domains, the malefactors are attempting to hinder the victim from connecting to relevant and helpful ransomware-attack-related information online. Malware also stores two .txt files on the victim’s computer that provide particulars related to the attack – the victim’s public encryption key and personal ID. These two files are named bowsakkdestx.txt and PersonalID.txt.

After all these changes, the malware doesn’t cease. Variants of STOP/DJVU tend to install Vidar password-stealing Trojan on compromised systems. This threat has an huge list of capabilities, including:

Manipulating and viewing files on the victim’s computer without their knowledge.
Extracting sensitive information such as browser cookies, saved passwords, and browsing history.
Obtaining unauthorized access to login credentials of Steam, Telegram, and Skype.
Granting the hackers remote control over the victim’s computer for various malicious activities.
Stealing cryptocurrency wallets from the victim’s system.
Gathering sensitive data by running malicious software on the victim’s computer.

The encryption algorithm used by DJVU/STOP virus is AES-256. So, if your data got encrypted with an online decryption key, the chances to get your files back without paying the ransom are quite low. Thing is, this key is unique for each victim, and finding a suitable one will take exceptionally big amount of time.

Getting the online key in another way is also nearly impossible. It is stored on a remote server controlled by the crooks who spread the Qual malware. For receiving decryption key the payment should be $999. To see the payment details, the victims should contact the hackers by email ([email protected]).

The message by the ransomware states the following information:

ATTENTION!

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.
Do not ask assistants from youtube and recovery data sites for help in recovering your data.
They can use your free decryption quota and scam you.
Our contact is emails in this text document only.
You can get and look video overview decrypt tool:
https://we.tl/t-hPAqznkJKD
Price of private key and decrypt software is $999.
Discount 50% available if you contact us first 72 hours, that's price for you is $499.
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]

Reserve e-mail address to contact us:
[email protected]

Your personal ID:
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

How To Remove STOP/Djvu Ransomware?

Video Guide

How To Decrypt .qual Files?

How to restore big files?

Try removing .qual extension on a few big files and opening them. This malware has issues with large files encryption. Either the virus accessed and did not encode the file, or it failed and did not add the filemarker. If you have files that are very large (2GB+), the latter is most likely. Please, let me know in comments if that will work for you.

The newest extensions released around the end of August 2019 after the criminals made changes. This includes Sarut, Watz, Waqa etc.

As a outcome of the alterations made by the criminals, STOPDecrypter is no longer backed. It has been replaced with the Emsisoft Decryptor for STOP Djvu Ransomware developed by Emsisoft.

You can download free decryption tool here: Decryptor for STOP Djvu.

Select folders for decryption.

Based on the default configurations, the decryptor will by default choose the available directories in order to decode the currently accessible drives (the connected ones), including the network drives. Additional (optional) locations can be selected with the help of the “Add” button.

Decryptors usually offer several options considering the specific malware family. The present possible options are presented in the Options tab and can be turned on or turned off there. You may locate a detailed list of the currently active Options below.

Click on the “Decrypt” button.

As soon as you add all the desired locations for decryption into the list, click on the “Decrypt” button in order to initiate the decryption procedure.

Note that the main screen may turn you to a status view, letting you know of the active process and the decryption statistics of your data:

The decryptor will notify you as soon as the decryption procedure is completed. If you need the report for your personal papers, you can save it by choosing the “Save log” button. Note that it is also possible to copy it directly to your clipboard and to paste it into emails or messages here if you need to do so.

The Emsisoft Decryptor might display different messages after a failed attempt to restore your files:

✓ Error: Unable to decrypt file with ID: [your ID]

There is no corresponding decryption key in the Emsisoft decryptor’s database.

✓ No key for New Variant online ID: [your ID]

Notice: this ID appears to be an online ID, decryption is impossible

Your original files were encrypted with an online key. So no one else has the same encryption/decryption key pair. Recovery of files without paying the criminals is impossible. 🙁

✓ Result: No key for new variant offline ID: [example ID]

This ID appears be an offline ID. Decryption may be possible in the future.

An offline key was used, but files could not be restored (the offline decryption key isn’t available yet). Nonetheless, receiving this message is good news for you, since it is possible to restore your files in the future. 🙂

It can take a few weeks or months until the decryption key gets found and uploaded to the decryptor. Please follow updates regarding the decryptable DJVU versions here.

✓ Remote name could not be resolved

It’s an indication of a DNS issue on your PC. Our first recommendation is to reset your HOSTS file back to default.

How to Restore .qual Files?

In some case ransomware is not doom for your files…

The Qual ransomware encryption mechanism is next: it ciphers every file byte-by-byte, then saves a duplicate, erasing (not overriding!) the initial file. Thus, the information of the file location on the physical disk is lost, but the original file is not deleted from the physical disk. The cell, or the sector where this file was kept, can still keep this file, but it is not present in the file system and can be replaced by data that has been loaded to this drive after the deletion. Hence, it is possible to restore your files using special software.

I recently had my pc infected by the this virus. It managed to bypass 2 Antivirus software and 2 malware fighters.

Anyway, after realizing it was an online algorithm, it is impossible to retrieve my encrypted files. I also had my backup drive plugged in at the time of the virus, and this was also infected, or so I thought. Every folder within my backup drive had been infected and was encrypted. However, despite losing some important files, I retrieved almost 80% of my 2TB storage.

When I started going through the folders, I noticed the readme.txt ransom note in every folder. I opened some of the folders and found that all files that were not in a subfolder within that folder had been encrypted. However, I found a flaw and glimmer of hope when I went into the subfolders in other folders and found that these files had not been encrypted. Every folder within my c and d drives, including subfolders, had been encrypted, but this was not the case with the backup drive. Having subfolders created within a folder has saved 80% of my data.

As I said, I believe this to be only a small loophole on a backup drive. I’ve since found a further 10 % of my data on another hard drive on a different pc. So my advice is if you use a backup drive, create subfolders. I was lucky, I guess. But I was also unlucky that the virus hit as I was transferring some files from my backup.

Hopefully, this can help some other people in my situation.

Jamie Newland

Some pointers for recovery repair of Qual files (true for all STOP/DJVU variants):

I have seen Stop/Djvu variants fail to encrypt deeper nested folders, so that you can check that. You may find those are not encrypted.

This ransomware saves encrypted data to a new file, deletes the original. So there’s a slight chance part of that deleted file can be recovered using file recovery software. It’s unlikely the folder structure can be restored, so a free tool like PhotoRec may be as good as any.

This ransomware only partially encrypts (about the first 150 KB), so depending on file size and type of data, the not encrypted part may be recoverable.

Joep

Recovering your files with PhotoRec

PhotoRec is an free program, which is originally created for file retrieval from damaged disks, or for file retrieval in case if they are unintentionally deleted. However, with time flow, this program received the ability to restore the files of 400 different extensions. Hence, it can be used for file recovery after the Qual attack.

First, you need to download this app. It is 100% free, but the developer notifies that there is no assurance that the files will be retrieved. PhotoRec is distributed in a pack with other program of the same developer – TestDisk. The downloaded archive will bear TestDisk name, but don’t worry. PhotoRec files are right inside.

To open PhotoRec, find and open “qphotorec_win.exe” file. No installation is needed – the program has all the files it need within the archive, hence, you can mount it on your USB drive, and try to help your friends/parents/anyone who has been attacked by Qual ransomware.

Upon the launch, you will see the screen showing you the complete list of your drives. However, this details are likely irrelevand, because the required menu is placed a bit higher. Click this menu, then choose the disk which was attacked by ransomware.

After opting for the disk, you need to select the destination folder for the reclaimed files. This menu is located at the lower part of the PhotoRec window. The best selection is to export them on USB drive or any other type of removable disk.

Then, you need to designate the file formats. This option is located at the bottom, too. As it was mentioned, PhotoRec can restore the files of about 400 different formats.

Finally, you can begin files restoration by pressing the “Search” button. You will observe the screen where the findings of the scan and recovery are shown.

Qual files recovery Video Guide.

Frequently Asked Questions

🤔 How can I open “.qual” files?

No way. These files are encrypted by ransomware. The contents of encrypted files are not available until they are decrypted.

🤔 This virus has blocked infected PC: I can’t get the activation code.

In this situation, you need to prepare the memory stick with a pre-installed

🤔 Decryptor did not decrypt all my files, or not all of them were decrypted. What should I do?

Have patience. You are infected with the new version of STOP/DJVU ransomware, and decryption keys have not yet been released. Follow the news on our website. We will keep you posted on when new keys or new decryption programs appear.

🤔 What can I do right now?

The Qual ransomware encrypts only the first 150KB of files. So MP3 files are rather large, some media players (Winamp for example) may be able to play the files, but – the first 3-5 seconds (the encrypted portion) will be missing. You can try to find a copy of an original file that was encrypted: Files you downloaded from the Internet that were encrypted and you can download again to get the original.

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Brendan Smith