Cuag ransomware (virus) - Decryption Steps Included
Cuag virus Removal Guide
What is Cuag ransomware?
Cuag ransomware is a malicious program designed to demand money from the virus victims
The threat that demands money for the alleged data recovery
When the infection starts the infiltration, users might not notice any strange activities, but the Cuag file virus manages to damage the processes, programs on the machine and directly affect the stage of commonly used files. This is a really malicious and dangerous cyber threat.
Once inside the system, it encrypts all personal pictures videos documents archives, or other files by using an encryption algorithm that also appends a unique .cuag extension to each encrypted file's name. The process makes all data unreadable by anyone except those who have the key which is in possession of criminals behind this ransomware attack. This information can be found within the _readme.txt file placed on the desktop and in other folders.
There are many different types of malware that can affect your computer. One of the most dangerous types is ransomware that this Cuag virus is. It will encrypt all files on the victim’s device and provide the information with an intimidating message demanding money in return for the decryption. This cryptovirus was created specifically as a means to take financial advantage of people. The threat actors ask for a payment of Bitcoin that is starting with $490 and come up to $980.
|Ransomware family||Djvu ransomware|
|Distribution||Files attached to emails can have ransomware payload, pirating platforms are known for distributing threats during installs of various games and software|
|Contact email@example.com, firstname.lastname@example.org|
|Ransom amount||Starts with $490 as a discount. Goes up to $980|
|Removal||You need tools like SpyHunter 5Combo Cleaner or Malwarebytes for the proper ransomware removal, so run the full system scan and remove the infection properly|
|PC repair||Threats affect more than common files because the infection manages to alter files and system functions, run the tool RestoroIntego for the remediation on the machine|
You are advised to avoid paying the requested fee because there's always hope for restoration even without purchasing some kind of software or key from criminals who will only keep on promises but never deliver anything. The official decryption tool is not available, so it is not easy to achieve full file recovery, but removing the infection is crucial here.
When the virus locks down your device, it will encrypt all files and it comes out of nowhere. The threat can come when users download and open cracked or pirated software. They are activating a virus that can affect their system's performance significantly.
This is because of how the encryption process works alongside other functions conducted by cryptomalware. Cuag file viruses can damage files, functions, and other programs for the sake of virus detection avoidance. It ensures the persistence to keep the machine running the threat and additional infections.
The infection focuses on file-locking
The family of dangerous ransomware
The developers of this nasty file-locking parasite want to persuade you that the only way to regain access is by purchasing their decryption software. And they're trying really hard to convince. The discount is offered for the first 72 hours after the Cuag ransomware encryption process.
Cryptovirus belongs to the malware family known as STOP virus and is derived from Djvu ransomware virus directly. This malicious software encrypts files since 2018 and changes introduced in August 2019 make the threat not decryptable, unfortunately. It is a bummer for victims, but there are alternate options that we list through the article.
These decryption options depend on the encryption keys and IDs formed during the process. The latest versions like the Cuag file virus, use the online IDs that are formed precisely for each different device that is affected. This way the decryption is only possible when the key is obtained by law enforcement or after payment.
If your computer got infected with one of the Djvu variants, you should try using Emsisoft decryptor for Djvu/STOP. It is important to mention that this tool will not work for everyone – it only works if data was locked with an offline ID due to malware failing to communicate with its remote servers.
Even if your case meets this condition, somebody from the victims has to pay criminals, retrieve an offline key, and then share it with security researchers at Emsisoft. As a result, you might not be able to restore the encrypted files immediately. Thus, if the decryptor says your data was locked with an offline ID but cannot be recovered currently, you should try later. You also need to upload a set of files – one encrypted and a healthy one to the company's servers before you proceed.
- Download the app from the official Emsisoft website.
- After pressing Download button, a small pop-up at the bottom, titled decrypt_STOPDjvu.exe should show up – click it.
- If User Account Control (UAC) message shows up, press Yes.
- Agree to License Terms by pressing Yes.
- After Disclaimer shows up, press OK.
- The tool should automatically populate the affected folders, although you can also do it by pressing Add folder at the bottom.
- Press Decrypt.
From here, there are three available outcomes:
- “Decrypted!” will be shown under files that were decrypted successfully – they are now usable again.
- “Error: Unable to decrypt file with ID:” means that the keys for this version of the virus have not yet been retrieved, so you should try later.
- “This ID appears to be an online ID, decryption is impossible” – you are unable to decrypt files with this tool.
Removing the infection and restoring the performance of the machine
Experts recommend not paying the ransom, as cybercriminals might not keep their promises. Different ransomware is rapidly infecting computers after encrypting users' files. Some types of malware are practically impossible to eliminate without specific tools or options for data recovery. Others can be removed using regular antivirus software like SpyHunter 5Combo Cleaner or Malwarebytes.
You should base this tool selection on the fact that mainly this family is detected by various AV tools and can be terminated using a security application like this when the system is fully scanned and checked for malicious pieces. You can find additional issues on the system not only the ransomware, so make sure to remove all the listed programs from the device.
Ransomware infections are delivering the same ransom note for years now
We recommend getting rid of the Cuag file virus as soon as you notice issues with the machine. These applications can help eliminate the threat and all its files or related programs. It is up to the cybercriminal whether they will provide the necessary tool or not. This is why it's best not to trust criminals and pay ransoms that can cost thousands of dollars. You can remove the infection fully and then worry about those affected files.
Cuag virus can be exceptionally dangerous if you do not react as soon as possible. The demand for $980 or $490 in Bitcoin with the discount can look manageable when your files are valuable. However, you should never consider payment as the best option for this infection and data recovery. If you contact criminals via email@example.com, firstname.lastname@example.org, you get another infection instead of the decryption tool or any other help.
Once a computer is infected with malware, its system is changed to operate differently. For example, an infection can alter the Windows registry database, damage vital bootup, and other sections, delete or corrupt DLL files, etc. Once a system file is damaged by malware, antivirus software is not capable of doing anything about it, leaving it just the way it is. Consequently, users might experience performance, stability, and usability issues, to the point where a full Windows reinstallation is required.
Therefore, we highly recommend using a one-of-a-kind, patented technology of RestoroIntego repair. Not only can it fix virus damage after the infection, but it is also capable of removing malware that has already broken into the system thanks to several engines used by the program. Besides, the application is also capable of fixing various Windows-related issues that are not caused by malware infections, for example, Blue Screen errors, freezes, registry errors, damaged DLLs, etc.
- Download the application by clicking on the link above
- Click on the ReimageRepair.exe
- If User Account Control (UAC) shows up, select Yes
- Press Install and wait till the program finishes the installation process
- The analysis of your machine will begin immediately
- Once complete, check the results – they will be listed in the Summary
- You can now click on each of the issues and fix them manually
- If you see many problems that you find difficult to fix, we recommend you purchase the license and fix them automatically.
File encryption and Cuag ransomware infection are two independent processes, but cryptocurrency extortion happens when there is a virus running in your operating system. The same goes for file recovery and virus removal. Threat actors have the option of blackmailing you because they can make changes within the system. You need to terminate the infection and then can repair files with options available to you.
You should copy the encrypted files onto a separate medium, such as a USB flash drive or SSD, and then disconnect them. Encrypted data does not hold any malicious code so it's safe to transfer between devices. Then you can wait for some decryption tool developments later. The Cuag ransomware virus infection has caused issues. The threat may also lock down various applications needed for data recovery and system functions.
Getting rid of Cuag virus. Follow these steps
Important steps to take before you begin malware removal
File encryption and ransomware infection are two independent processes (although the latter would not be possible without the former). However, it is important to understand that malware performs various changes within a Windows operating system, fundamentally changing the way it works.
IMPORTANT for those without backups! →
If you attempt to use security or recovery software immediately, you might permanently damage your files, and even a working decryptor then would not be able to save them.
Before you proceed with the removal instructions below, you should copy the encrypted files onto a separate medium, such as USB flash drive or SSD, and then disconnect them from your computer. Encrypted data does not hold any malicious code, so it is safe to transfer to other devices.
The instructions below might initially seem overwhelming and complicated, but they are not difficult to understand as long as you follow each step in the appropriate order. This comprehensive free guide will help you to handle the malware removal and data recovery process correctly.
If you have any questions, comments, or are having troubles with following the instructions, please do not hesitate to contact us via the Ask Us section.
It is vital to eliminate malware infection from the computer fully before starting the data recovery process, otherwise ransomware might re-encrypt retrieved files from backups repeatedly.
Restore Windows "hosts" file to its original state
Some ransomware might modify Windows hosts file in order to prevent users from accessing certain websites online. For example, Djvu ransomware variants add dozens of entries containing URLs of security-related websites, such as 2-spyware.com. Each of the entries means that users will not be able to access the listed web addresses and will receive an error instead.
Here's an example of “hosts” file entries that were injected by ransomware:
In order to restore your ability to access all websites without restrictions, you should either delete the file (Windows will automatically recreate it) or remove all the malware-created entries. If you have never touched the “hosts” file before, you should simply delete it by marking it and pressing Shift + Del on your keyboard. For that, navigate to the following location:
Restore files using data recovery software
Since many users do not prepare proper data backups prior to being attacked by ransomware, they might often lose access to their files permanently. Paying criminals is also very risky, as they might not fulfill the promises and never send back the required decryption tool.
While this might sound terrible, not all is lost – data recovery software might be able to help you in some situations (it highly depends on the encryption algorithm used, whether ransomware managed to complete the programmed tasks, etc.). Since there are thousands of different ransomware strains, it is immediately impossible to tell whether third-party software will work for you.
Therefore, we suggest trying regardless of which ransomware attacked your computer. Before you begin, several pointers are important while dealing with this situation:
- Since the encrypted data on your computer might permanently be damaged by security or data recovery software, you should first make backups of it – use a USB flash drive or another storage.
- Only attempt to recover your files using this method after you perform a scan with anti-malware software.
Install data recovery software
- Download Data Recovery Pro.
- Double-click the installer to launch it.
- Follow on-screen instructions to install the software.
- As soon as you press Finish, you can use the app.
- Select Everything or pick individual folders where you want the files to be recovered from.
- Press Next.
- At the bottom, enable Deep scan and pick which Disks you want to be scanned.
- Press Scan and wait till it is complete.
- You can now pick which folders/files to recover – don't forget you also have the option to search by the file name!
- Press Recover to retrieve your files.
Create data backups to avoid file loss in the future
One of the many countermeasures for home users against ransomware is data backups. Even if your Windows get corrupted, you can reinstall everything from scratch and retrieve files from backups with minimal losses overall. Most importantly, you would not have to pay cybercriminals and risk your money as well.
Therefore, if you have already dealt with a ransomware attack, we strongly advise you to prepare backups for future use. There are two options available to you:
- Backup on a physical external drive, such as a USB flash drive or external HDD.
- Use cloud storage services.
The first method is not that convenient, however, as backups need to constantly be updated manually – although it is very reliable. Therefore, we highly advise choosing cloud storage instead – it is easy to set up and efficient to sustain. The problem with it is that storage space is limited unless you want to pay for the subscription.
Using Microsoft OneDrive
OneDrive is a built-in tool that comes with every modern Windows version. By default, you get 5 GB of storage that you can use for free. You can increase that storage space, but for a price. Here's how to setup backups for OneDrive:
- Click on the OneDrive icon within your system tray.
- Select Help & Settings > Settings.
- If you don't see your email under the Account tab, you should click Add an account and proceed with the on-screen instructions to set yourself up.
- Once done, move to the Backup tab and click Manage backup.
- Select Desktop, Documents, and Pictures, or a combination of whichever folders you want to backup.
- Press Start backup.
After this, all the files that are imported into the above-mentioned folders will be automatically backed for you. If you want to add other folders or files, you have to do that manually. For that, open File Explorer by pressing Win + E on your keyboard, and then click on the OneDrive icon. You should drag and drop folders you want to backup (or you can use Copy/Paste as well).
Using Google Drive
Google Drive is another great solution for free backups. The good news is that you get as much as 15GB for free by choosing this storage. There are also paid versions available, with significantly more storage to choose from.
You can access Google Drive via the web browser or use a desktop app you can download on the official website. If you want your files to be synced automatically, you will have to download the app, however.
- Download the Google Drive app installer and click on it.
- Wait a few seconds for it to be installed.
- Now click the arrow within your system tray – you should see Google Drive icon there, click it once.
- Click Get Started.
- Enter all the required information – your email/phone, and password.
- Now pick what you want to sync and backup. You can click on Choose Folder to add additional folders to the list.
- Once done, pick Next.
- Now you can select to sync items to be visible on your computer.
- Finally, press Start and wait till the sync is complete. Your files are now being backed up.
Report the incident to your local authorities
Ransomware is a huge business that is highly illegal, and authorities are very involved in catching malware operators. To have increased chances of identifying the culprits, the agencies need information. Therefore, by reporting the crime, you could help with stopping the cybercriminal activities and catching the threat actors. Make sure you include all the possible details, including how did you notice the attack, when it happened, etc. Additionally, providing documents such as ransom notes, examples of encrypted files, or malware executables would also be beneficial.
Law enforcement agencies typically deal with online fraud and cybercrime, although it depends on where you live. Here is the list of local authority groups that handle incidents like ransomware attacks, sorted by country:
- USA – Internet Crime Complaint Center IC3
- United Kingdom – ActionFraud
- Canada – Canadian Anti-Fraud Centre
- Australia – ScamWatch
- New Zealand – ConsumerProtection
- Germany – Polizei
- France – Ministère de l'Intérieur
If your country is not listed above, you should contact the local police department or communications center.
Manual removal using Safe Mode
Manual removal guide might be too complicated for regular computer users. It requires advanced IT knowledge to be performed correctly (if vital system files are removed or damaged, it might result in full Windows compromise), and it also might take hours to complete. Therefore, we highly advise using the automatic method provided above instead.
Step 1. Access Safe Mode with Networking
Manual malware removal should be best performed in the Safe Mode environment.
Windows 7 / Vista / XP
- Click Start > Shutdown > Restart > OK.
- When your computer becomes active, start pressing F8 button (if that does not work, try F2, F12, Del, etc. – it all depends on your motherboard model) multiple times until you see the Advanced Boot Options window.
- Select Safe Mode with Networking from the list.
Windows 10 / Windows 8
- Right-click on Start button and select Settings.
- Scroll down to pick Update & Security.
- On the left side of the window, pick Recovery.
- Now scroll down to find Advanced Startup section.
- Click Restart now.
- Select Troubleshoot.
- Go to Advanced options.
- Select Startup Settings.
- Press Restart.
- Now press 5 or click 5) Enable Safe Mode with Networking.
Step 2. Shut down suspicious processes
Windows Task Manager is a useful tool that shows all the processes running in the background. If malware is running a process, you need to shut it down:
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Click on More details.
- Scroll down to Background processes section, and look for anything suspicious.
- Right-click and select Open file location.
- Go back to the process, right-click and pick End Task.
- Delete the contents of the malicious folder.
Step 3. Check program Startup
- Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
- Go to Startup tab.
- Right-click on the suspicious program and pick Disable.
Step 4. Delete virus files
Malware-related files can be found in various places within your computer. Here are instructions that could help you find them:
- Type in Disk Cleanup in Windows search and press Enter.
- Select the drive you want to clean (C: is your main drive by default and is likely to be the one that has malicious files in).
- Scroll through the Files to delete list and select the following:
Temporary Internet Files
- Pick Clean up system files.
- You can also look for other malicious files hidden in the following folders (type these entries in Windows Search and press Enter):
After you are finished, reboot the PC in normal mode.
Finally, you should always think about the protection of crypto-ransomwares. In order to protect your computer from Cuag and other ransomwares, use a reputable anti-spyware, such as RestoroIntego, SpyHunter 5Combo Cleaner or Malwarebytes
How to prevent from getting ransomware
Choose a proper web browser and improve your safety with a VPN tool
Online spying has got momentum in recent years and people are getting more and more interested in how to protect their privacy online. One of the basic means to add a layer of security – choose the most private and secure web browser. Although web browsers can't grant full privacy protection and security, some of them are much better at sandboxing, HTTPS upgrading, active content blocking, tracking blocking, phishing protection, and similar privacy-oriented features. However, if you want true anonymity, we suggest you employ a powerful Private Internet Access VPN – it can encrypt all the traffic that comes and goes out of your computer, preventing tracking completely.
Lost your files? Use data recovery software
While some files located on any computer are replaceable or useless, others can be extremely valuable. Family photos, work documents, school projects – these are types of files that we don't want to lose. Unfortunately, there are many ways how unexpected data loss can occur: power cuts, Blue Screen of Death errors, hardware failures, crypto-malware attack, or even accidental deletion.
To ensure that all the files remain intact, you should prepare regular data backups. You can choose cloud-based or physical copies you could restore from later in case of a disaster. If your backups were lost as well or you never bothered to prepare any, Data Recovery Pro can be your only hope to retrieve your invaluable files.
- ^ Zondervirus. Zondervirus. Spyware related news.
- ^ Virus sample. VirusTotal. Virus scanner online.
- ^ Missing DLL files errors. Windowsclub. Windows issue reports.