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Cuag Virus


Cuag is an advanced malware version of the Ransomware file-encrypting family that will make your data inaccessible by applying encryption to each file. Cuag will then blackmail you for a ransom payment that you must pay to get your files back.

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The Cuag virus file ransomware

A number of web users have recently contacted our “How to remove” team regarding an infection called Cuag. This threat is a Ransomware cryptovirus the main goal of which is to scan your system for specific types data. Normally, these include work or personal documents, all sorts of pictures or videos, audios, archives and other files that may be considered as valuable. The next thing the virus does after locating the files in the HDD is it encrypts them one by one by applying a very complex algorithm of symbols which cannot be decrypted without a special decryption key. This way, Cuag makes the files inaccessible and starts to blackmail the victim to pay a ransom in order to obtain the required decryption key for decoding the sealed data. The hackers who hold the key typically provide instructions of payment in the form of a ransom notification which gets displayed on the screen of the infected computer immediately after the secret encryption process completes. The amount of the ransom that they require may vary from several hundred to several thousand dollars and very much depends on whether the victim is a regular user or a representative of a large organization or institution. Most often, the crooks behind the Ransomware require a payment in bitcoins or in anther cyber-currency as those are quite difficult for the authorities to trace. The victims are given a short deadline to fulfill the demands of the criminals and are usually threatened that, if the demands are no fulfilled in time, the files locked by the Ransomware would stay this way forever.

The Cuag virus

The Cuag virus is a threatening malware program capable of getting inside almost any computer and secretly placing encryption on all user files stored there. To break the Cuag virus encryption, the user needs a special key that only the hackers have.

The people who have been attacked, however, should know that the file-encryption applied by threats like Cuag or Avyu can often turn out to be irreversible and, in such cases, even the decryption key from the hackers may not be able to bring the data back to normal. In the world of programming and data encryption, the slightest mistake in the code can significantly affect the end result. Unfortunately, if the victims transfer the ransom that the criminals demand and the key that they receive doesn’t work, there would be no refunds and the money would still be gone regardless of whether the users get their files back or not. Not to mention that the hackers don’t really care if you can ever use your precious files again or not as long as they receive the payment, so it’s even possible that they do not send you a decryption key whatsoever.

The Cuag file

If you are reading this because your PC has been attacked by the Cuag file, then you may be more than interested in learning about the possible alternatives of dealing with this nasty threat and the methods that you can use to have it removed. That’s why we suggest you do not to rush with any ransom payments to the criminals and take a close look at the information that follows.

The .cuag file virus

In the paragraphs below, we have prepared a detailed removal guide with instructions, a professional scanner for fast detection and elimination of the Ransomware and a file-recovery section with suggestions on how to get back some of your encrypted files without paying a ransom. Please, keep in mind though, that as much as we want to help you, the Ransomware-based programs are some of the hardest types of malware to fight and no guarantee can be given about the full recovery from their attacks.


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Remove Cuag Ransomware

As a first step, please bookmark this page with the Cuag removal steps for quick access.

After that, restart your PC in Safe Mode in order to limit the number of running system processes down to the most essential ones. Detailed instructions on how to restart your computer in Safe Mode may be found at this URL.

As soon as the system reboots in Safe Mode, click on the Windows Search field and type msconfig, then hit Enter from the keyboard.

The System Configuration window will open on the screen. In the Startup tab, search for unusual startup items that Cuag might have added and uncheck their checkboxes if you believe that there is something dangerous. Save your settings by clicking the OK button.


When the ransomware virus is active, a number of harmful processes may be detected in the Task Manager. Locating and ending these processes is the next thing that you should do in this step.

Simply press CTRL, SHIFT, and ESC on your keyboard to open the Task Manager. Then, search for a ransomware-related process in the Processes tab, right-click on it and select Open File Location from the context menu.

After that, use the free virus scanner offered below to check the files connected with that process for malware:

Each file will be scanned with up to 64 antivirus programs to ensure maximum accuracy
This scanner is free and will always remain free for our website's users.
This file is not matched with any known malware in the database. You can either do a full real-time scan of the file or skip it to upload a new file. Doing a full scan with 64 antivirus programs can take up to 3-4 minutes per file.
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Each file will be scanned with up to 64 antivirus programs to ensure maximum accuracy
    This scanner is based on VirusTotal's API. By submitting data to it, you agree to their Terms of Service and Privacy Policy, and to the sharing of your sample submission with the security community. Please do not submit files with personal information if you do not want them to be shared.

    In order to delete any harmful files that the scanner has identified, you must first stop the associated process in Task Manager. To do that, right-click on the process and select End Process from the quick list of options.

    The Hosts file is the next place that you need to check for changes if your computer has been attacked. This means you should open your Hosts file, search for modifications under Localhost in the text, and double-check that everything is in order before proceeding further.

    For this, open a Run dialog box by pressing Windows Key + R at the same time, and then paste the following command into it:

    notepad %windir%/system32/Drivers/etc/hosts

    This file should show on your screen when you click OK:

    Let us know if you come across any IP addresses like those in the image above. We’ll investigate any IPs that appear to be suspicious and provide you with some guidance on what to do with them.

    When your computer gets infected with ransomware, it is more than likely that dangerous files will be added to the Registry. For this reason, you must check the Registry for malicious entries and delete all traces of the infection that you find there.

    The Registry Editor can be accessed by typing Regedit into the Windows search field and pressing Enter. Open the Editor’s Find dialog box by pressing CTRL and F at the same time, and type the ransomware’s name into it. Then, click the Find Next button and begin a search to check if there are any entries with that name. It’s best to get rid of everything related to the infection that is identified in the search results.

    Attention! If a user does not know which registry files to delete, he or she may inadvertently harm the system. As a result, malware and potentially harmful files should best be removed from the system and the registry using only a specialized removal program.

    After you have confirmed that the Registry is clean, we recommend you do a manual search for harmful files in the following five locations:

    1. %AppData%
    2. %LocalAppData%
    3. %ProgramData%
    4. %WinDir%
    5. %Temp%

    Simply type each of the lines above (including a percent sign) in your Windows Search field and press Enter to go to the relevant results. After that, look for new files or folders and sub-folders with strange names in each of them.

    Remove any suspicious items as soon as you notice them. Select all the temporary files in Temp and delete them all. The malware’s temporary files will be deleted as a result of this action.

    How to Decrypt Cuag files

    A number of tools and methods may be required to decode the data encrypted by a ransomware like Cuag. If you’ve been attacked, the first thing you need to do is figure out which ransomware version has encrypted your data. This can be found out by looking at the encrypted files’ file extensions.

    New Djvu Ransomware

    STOP Djvu ransomware is the most recent Djvu ransomware variant that is aggressively seeking to infect systems worldwide. All files encrypted by this ransomware version end with the extension .Cuag. STOP Djvu-encoded files can only be decoded with an offline key at this time. We’ve attached a link to a decryption program that you may find helpful in decrypting your data:

    Downloading STOPDjvu.exe is as simple as clicking the “Download” button from the URL.

    You can open the file by selecting “Run as administrator” and then pressing the Yes button. You can begin decrypting data after reading the license agreement and the short instructions for use. To start the actual decryption process, you need to click on the Decrypt button. Please bear in mind that this decryptor doesn’t support files encrypted with unknown offline keys or online encryption, thus, such files may not be decoded.

    Also, remember that your computer’s security can be improved by using an anti-virus program or an advanced online virus scanner. Don’t hesitate to write to us if you have any questions or concerns as you go through this guide!

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