UAJS Virus (.uajs File) How to Decrypt & Remove Ransomware?

The Uajs virus, also known as a ransomware, belongs to the STOP family. This malware family is notorious for malignant file encryption operations. When the Uajs virus infects a computer system, it targets various types of files, such as videos, photos, documents, and more. It alters the file structure and appends the “.uajs” extension to each encrypted file, making them unusable without the decryption key.

Uajs Virus Overview

Uajs

🤔 Uajs malware is ransomware that originates from the DJVU/STOP family. Its primary purpose is to cipher files that are important to you. Then, ransomware virus asks its victims for a ransom fee – ($499 – $999) in Bitcoin.

The Uajs virus is a type of malware that encrypts your files and forces you to pay for their recovery. This ransomware encrypts a wide selection of file types. ciphered files are identifiable by a distinct “.uajs” extension. The files touched by ransomware become impossible to access and use.

After that, the ransomware demands a file decryption payment in Bitcoin from the victims, ranging from $499 to $999. In all cases, a ransom text file is named as “_readme.txt“.

Uajs Ransomware works with Salsa20 encryption algorithms to cipher the files. Since Uajs virus applies such a strong ciphering method, it becomes pretty hard, if not impossible, to find the decryption key without the assistance of the attackers.

Once Uajs malware finishes the encryption, it shows a ransom note to the victim, asking for a ransom payment in exchange for the decryption key. The ransom note contains instructions on how to make the payment and also often contains threats of permanent data loss or ransom amounts surge if the demands are not met within a specified timeframe.

I have made an all-encompassing list of the solutions, advice, and practices to remove the Uajs virus and recover your files. There are situations when you can recover the files, while sometimes, it may be impossible.

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📌 Important Note!

It is important to say that paying off the bill does not guarantee the successful files recovery. The hackers behind the Uajs virus are known for their untrustworthiness. There have been instances where victims have paid the ransom, only to be denied by the cybercriminals with the decryption key provision.

Uajs employs a unique key for every victim, with one exception:

If Uajs fails to establish a connection with its command and control server (C&C Server) before starting the encryption process, it uses offline keys as a fallback option. This key is the same for all users, which allows for the decryption of files encrypted by the ransomware.

The Uajs virus bears resemblance to other DJVU ransomware samples such as Uazq, Vook, Looy, and Kool. This virus encrypts a wide range of common file types and appends its distinct “.uajs” extension to all files. For instance, a file named “1.jpg” would be altered to “1.jpg.uajs” and “2.png” to “2.png.uajs“.

After successful encryption, malware spawns a special text file named “_readme.txt” and places it in every folder containing the encrypted files. It as well adds the readme file to the desktop, so the user will not miss its appearance even without opening folders.

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

Encrypted Files by STOP/DJVU Ransomware

Name	Uajs Virus
Ransomware family¹	DJVU/STOP² ransomware
Extension	.uajs
Ransomware note	_readme.txt
Ransom	From $499 to $999 (in Bitcoins)
Contact	[email protected], [email protected]
Detection	MSIL/TrojanDownloader.Agent.PYG Virus Removal, Trojan:MSIL/AgentTesla.MBCS!MTB Virus Removal, MSIL/TrojanDownloader.Agent_AGen.AXJ Virus Removal
Symptoms	Encrypted most of your files (photos, videos, documents) and adds a particular “.uajs” extension; Can delete Volume Shadow copies to make victim’s attempts to restore data impossible; Adds a list of domains to HOSTS file to block access to certain security-related sites; Installs password-stealing Trojan on the system, like Vidar Stealer or RedLine Stealer; Manages to install a SmokeLoader backdoor;
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 terrifying notification requesting users to pay off the ransom to unlock the encoded data contains these frustrating admonitions.

Uajs ransomware arrives as a set of operations that are meant to perform certain tasks on a victim’s computer. One of the primary ones being launched is winupdate.exe, a deceptive process that shows a false Windows update alert during the attack. That is needed to convince the victim that a sudden system slowdown is caused by a Windows update.

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

vssadmin.exe Delete Shadows /All /Quiet

Once erased, it becomes virtually impossible to recover the previous computer state using System Restore Points. The concern is, ransomware operators are getting rid of any built-in Windows approaches that could aid the victim to restore files for free. In addition, the hackers modify the Windows HOSTS file by appending a list of domains to it and mapping them to the localhost IP. As a result, the victim will encounter a DNS_PROBE_FINISHED_NXDOMAIN error when accessing one of the blocked websites.

We noticed that ransomware endeavors to restrict websites that promote various how-to guides for computer users. It is obvious that by restricting specific domains, the malefactors are attempting to prevent the victim from reaching relevant and helpful ransomware-attack-related information online. The virus also stores two text files on the victim’s computer that offer information related to the attack – the public key of this victim and personal ID. These two files are named bowsakkdestx.txt and PersonalID.txt.

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

Stealing Steam, Telegram, Skype login / password;
Stealing cryptocurrency wallets;
Downloading other malware to the computer and running it;
Stealing browser cookies, saved passwords, browsing history, and more;
Viewing and manipulating files on victim’s computer;
Allowing the hackers to perform other tasks on the victim’s computer remotely.

The cryptography algorithm used by DJVU/STOP virus is AES-256. So, once your data is encrypted with an online decryption key, the chances to get your files back are quite low. Thing is, this key is unique for each victim, and brute forcing it will take too much time.

Getting the online decryption key in another way is also merely impossible. It is stored on a command server controlled by the criminals who spread the Uajs infection. 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 .uajs Files?

How to restore big files?

Try removing .uajs extension on a few big files and opening them. This malware has issues with large files encryption. Either the virus accessed and did not lock the file, or it bugged and did not add the filemarker. If your files are very large (2GB+), the latter is most likely. Please, text me in the comments whether this helped you or not.

The newest extensions released around the end of August 2019 after the criminals made changes. This includes Uazq, Vook, Looy etc.

As a outcome of the changes made by the criminals, STOPDecrypter is no longer supported. 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 reachable directories in order to decode the currently accessible drives (the connected ones), including the network drives. You can choose other locations with the “Add” button.

Decryptors typically offer several options depending on the specific malware family. The existing possible options are shown in the Options tab and can be enabled or deactivated 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. There is no one to share the decryption key with you. 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.

Malware used an offline key, though the file recovery operation failed (the offline decryption key isn’t available yet). But, receiving this message is good news for you, because it might be 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

This stands for a DNS issue present in your system. Consider resetting your HOSTS file to default.

How to Restore .uajs Files?

In some case ransomware is not doom for your files…

The Uajs ransomware encryption mechanism is next: it encodes every file byte-by-byte, then saves a duplicate, removing (not overriding!) the original file. Hence, the information of the file location on the disk drive is lost, but the original file is not deleted from the disk. The cell, or the sector where this file was kept, can still hold this file, but it is not present in the file system and can be rewritten by data that has been loaded to this disk after the removal. Hence, it is possible to recover 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 Uajs 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 initially created for files recovery from damaged disks, or for files recovery in case if they are unintentionally deleted. However, with time flow, this program adopted the ability to restore the files of 400 different formats. Hence, it can be used for file recovery after the Uajs attack.

First, you need to download this app. It is 100% free, but the developer states that there is no guarantee that your files will be recovered. PhotoRec is spread together with other tool of the same developer – TestDisk. The program 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 required – this 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 Uajs ransomware.

After the launch, you will encounter the screen showing you the full list of your disk drives. However, this details are presumably futile, because the required menu is placed a bit higher. Click this tab, then choose the disk which was attacked by ransomware.

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

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

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

Uajs files recovery Video Guide.

Frequently Asked Questions

🤔 How can I open “.uajs” 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 Uajs 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