Remove Coos ransomware (Virus Removal Instructions) - updated Jan 2021

removal by Ugnius Kiguolis - - | Type: Ransomware

Coos virus Removal Guide

What is Coos ransomware?

Coos ransomware – a new file-locking parasite made for cryptocurrency extortion

Coos ransomwareCoos ransomware is the virus that asks for at least $490 for the alleged decryption tool.

Coos ransomware is a new cryptovirus with a sole purpose – to shake down money from infected device owners. It does that by encrypting all non-system files with an army-grade RSA coding algorithm that renders the files inaccessible until a necessary decryption tool is used.

At the time of encryption, malware renames all personal victim files by appending a .coos extension. Afterward, it creates ransom notes, titled _readme.txt, and places them in every folder containing affected files. With these notes, assailants urge to contact them via given emails – and and lay down instructions on what to do to regain control of the locked data.

Coos virus belongs to the pervasive Djvu ransomware family. File-locking viruses from this lineage were first detected in December 2018, and since then, new versions are submitted each week or even more often, e.g., since the beginning of this year, our team already wrote about four new variants – Qlkm, Omfl, and Igal.

If you are wondering how to decrypt .coos files without paying the attackers, the situation is rather dire. However, there are several alternative methods that you could try – we list them below. Emsisoft's decryptor might help some victims to recover all the lost data, although it might not happen immediately.

name Coos ransomware
Type Ransomware
Family Djvu
Appended file extension All personal victim data (documents, databases, archives, etc.) is appended with a .coos extension
Ransom note _readme.txt can be found in all affected folders
Criminal contact details To establish contact, victims would need to contact their assailants via two given emails – and
Ransom amount The original decryption tool price (or the ransom amount) is $980, but if victims contact the criminals within 72 hours of encryption, a 50% discount is offered to lower the sum to $490
Virus removal Professional anti-malware software has to be used to completely and safely eliminate the cyber infection
System repair Cryptoviruses from this family makes modifications to the system registry, host files, and other core settings. To restore your device to normal, please use the ReimageIntego system repair tool

Ransom notes of cyber infections from the Djvu family are all the same. They differ very slightly. It begins with an explanation that all files were locked and that the only way to unlock them is by purchasing their decryption tool. And then the part to convince the victim to do it begins.

Hackers offer Coos virus victims to send them one encrypted file from the infected machine so they could decrypt it and send it back. Thus trying to prove that such a tool exists. Then they provide a link to a video where the deciphering tool can be seen in action.

And lastly, the creators of Coos ransomware are offering a 50% discount on the ransom amount for victims that contact them within 72 hours of the cyberattack. That lowers the buyout from the original price of $980 to $490. People who fail to reach out to the perpetrators within the given timeline would have to pay the whole amount.

In other words, the threat actors are bending over backward to persuade their victims to act quickly and meet their demands. The whole message from _readme.txt ransom note reads:


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.
You can get and look video overview decrypt tool:
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:

Reserve e-mail address to contact us:

Your personal ID:

Please don't give in to the cybercriminals' demands, as the only way to stop ransomware attacks is to stop paying its creators. Money gained from the Coos virus victims motivates hackers to develop new, more sophisticated malware and finances their research for improved delivery techniques.

Coos ransomware virusCoos ransomware - a cryptovirus that marks data using .coos appendix after encryption.

Victims that had their devices infected should remove Coos ransomware immediately. The best way to do it is by entrusting this task to professional anti-malware software such as SpyHunter 5Combo Cleaner and Malwarebytes. Only then people can rest assured that the infection is completely removed.

But before taking in on Coos ransomware removal, users should consider exporting their encrypted files to an offline storage device, like a USB drive or other, because if there's no decryption software available now, it should be created sooner or later.

Once you get rid of the cryptovirus, it's time to take care of your device's overall health. Ransomware from the Djvu family is famous for making various alterations to the Windows registry, host files, and other important files/settings, so it's highly recommended to perform a system repair with a powerful system tune-up app like the ReimageIntego.

Withhold from using file-sharing platforms to avoid cyber infections

Our research suggests that file-sharing platforms are a hotbed for Djvu family ransomware – it's the most popular spreading technique for file-locking parasites of this lineage. Torrent sites and other file-sharing platforms don't implement security measures to what people upload on their sites and what they're sharing.

Coos file virusCoos ransomware is a threat that demands money directly from victims.

Cybercriminals love to exploit that by disguising ransomware as anything that would lure their next victims. It could be a crack for the latest game or a fake installer for an expensive piece of software. The camouflaged payload file of a cryptovirus can come in many forms:

  • Text file
  • Zip/Rar archive
  • MS Office file
  • An executable file, or practically any other file type.

As soon as an infected file is downloaded, and if your default or licensed anti-malware fails to detect it – it starts its bidding. To avoid this nightmare, users are urged to stop choosing to use pirated software, illegal activation toolkits, and similar items.

Methods to restore .coos virus files

Statistically speaking, most of the victims who did get infected with ransomware never dealt with such an intrusion before. Therefore, there are many misconceptions about this type of malware in general. For example, it is widely perceived that ransomware elimination with security software would once again provide access to .coos virus files. Unfortunately, it is not the case at all – you will not regain control of your data just by performing a full system scan with a security tool. So, what options do you have?

The answer to this question is rather difficult, as it depends on many factors. For example, if the virus failed to eliminate Shadow Copies on the system, data recovery should be easily possible. Data recovery software might also be useful in some cases, although it is unlikely to bring all files back.

Your best bet is to try Emsisoft's decryptor for STOP Djvu. It is very important to note that it only works for users whose data was locked with an offline key (this happens when malware fails to communicate with the attackers' servers). Even then, somebody has to pay the criminals, retrieve the key, and then share it with security researchers for them to add it to the decryptor's database. Thus, it might take some time before you can recover .coos files using it.

Nonetheless, we recommend you download the tool and perform a scan to check whether the decryption with it is at all possible. Here's how to do it:

  • Download the app from the official Emsisoft website Download decryptor
  • After pressing Download button, a small pop-up at the bottom, titled decrypt_STOPDjvu.exe should show up – click it
    Click decrypt_STOPDjvu.exe
  • 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
    Add files
  • Press Decrypt.

From here, there are three outcomes that are available:

  1. Decrypted!” will be shown under files that were decrypted successfully – they are now usable again.
  2. 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
  3. This ID appears to be an online ID, decryption is impossible” – you are unable to decrypt .coos files with this tool.

Guide for Coos ransomware removal from infected devices

Ransomware attacks are on the rise, and they are not slowing down. Researchers predict,[1] that in 2021 this malware could cause more than $20 million in damages. So if you don't have a reliable anti-malware tool like SpyHunter 5Combo Cleaner or Malwarebytes, the time has never been better to get one.

Professional anti-virus software is needed not only to remove Coos ransomware but to prevent it from infecting the device. Virus databases of these type of apps should be updated every day because cybercriminals are relentless and develop new file-locking parasites constantly.

But please don't perform Coos ransomware removal until you copied the essential encrypted files from your device to offline storage. There's no decryptor available now, but companies are committed to helping ransomware victims by constantly updating their decryption tools.

Once the files are extracted and the Coos virus removed, it's time to repair your system. This type of malware encrypts only personal data, but it does extensive damage to various system settings and files, including the system registry, host files, etc., to establish persistence.

If left neglected, these modifications could cause various abnormal behavior such as the blue screen of death,[2] overheating, overall performance loss, and so on. To restore any alterations that the virus has accomplished, experts[3] recommend using the ReimageIntego system repair tool.

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Reimage Happiness
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Compatible with Microsoft Windows Compatible with macOS
What to do if failed?
If you failed to remove virus damage using Reimage Intego, submit a question to our support team and provide as much details as possible.
Reimage Intego has a free limited scanner. Reimage Intego offers more through scan when you purchase its full version. When free scanner detects issues, you can fix them using free manual repairs or you can decide to purchase the full version in order to fix them automatically.
Alternative Software
Different software has a different purpose. If you didn’t succeed in fixing corrupted files with Reimage, try running SpyHunter 5.
Alternative Software
Different software has a different purpose. If you didn’t succeed in fixing corrupted files with Intego, try running Combo Cleaner.

Getting rid of Coos virus. Follow these steps

Manual removal using Safe Mode

Eliminating cyber infections with Safe Mode with Networking

Important! →
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
  1. Click Start > Shutdown > Restart > OK.
  2. 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.
  3. Select Safe Mode with Networking from the list. Windows 7/XP
Windows 10 / Windows 8
  1. Right-click on Start button and select Settings.
  2. Scroll down to pick Update & Security.
    Update and security
  3. On the left side of the window, pick Recovery.
  4. Now scroll down to find Advanced Startup section.
  5. Click Restart now.
  6. Select Troubleshoot. Choose an option
  7. Go to Advanced options. Advanced options
  8. Select Startup Settings. Startup settings
  9. Press Restart.
  10. Now press 5 or click 5) Enable Safe Mode with Networking. Enable safe mode

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:

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Click on More details.
    Open task manager
  3. Scroll down to Background processes section, and look for anything suspicious.
  4. Right-click and select Open file location.
    Open file location
  5. Go back to the process, right-click and pick End Task.
    End task
  6. Delete the contents of the malicious folder.

Step 3. Check program Startup

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Go to Startup tab.
  3. 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:

  1. Type in Disk Cleanup in Windows search and press Enter.
    Disk cleanup
  2. 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).
  3. Scroll through the Files to delete list and select the following:

    Temporary Internet Files
    Recycle Bin
    Temporary files

  4. Pick Clean up system files.
    Delete temp files
  5. 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.

Remove Coos using System Restore

System Restore could be a helpful tool when trying to get rid of infections

  • Step 1: Reboot your computer to Safe Mode with Command Prompt
    Windows 7 / Vista / XP
    1. Click Start Shutdown Restart OK.
    2. When your computer becomes active, start pressing F8 multiple times until you see the Advanced Boot Options window.
    3. Select Command Prompt from the list Select 'Safe Mode with Command Prompt'

    Windows 10 / Windows 8
    1. Press the Power button at the Windows login screen. Now press and hold Shift, which is on your keyboard, and click Restart..
    2. Now select Troubleshoot Advanced options Startup Settings and finally press Restart.
    3. Once your computer becomes active, select Enable Safe Mode with Command Prompt in Startup Settings window. Select 'Enable Safe Mode with Command Prompt'
  • Step 2: Restore your system files and settings
    1. Once the Command Prompt window shows up, enter cd restore and click Enter. Enter 'cd restore' without quotes and press 'Enter'
    2. Now type rstrui.exe and press Enter again.. Enter 'rstrui.exe' without quotes and press 'Enter'
    3. When a new window shows up, click Next and select your restore point that is prior the infiltration of Coos. After doing that, click Next. When 'System Restore' window shows up, select 'Next' Select your restore point and click 'Next'
    4. Now click Yes to start system restore. Click 'Yes' and start system restore
    Once you restore your system to a previous date, download and scan your computer with ReimageIntego and make sure that Coos removal is performed successfully.

Bonus: Recover your data

Guide which is presented above is supposed to help you remove Coos from your computer. To recover your encrypted files, we recommend using a detailed guide prepared by security experts.

If your files are encrypted by Coos, you can use several methods to restore them:

Restore .coos extension files with Data Recovery Pro

This third-party app might help to restore encrypted files.

  • Download Data Recovery Pro;
  • Follow the steps of Data Recovery Setup and install the program on your computer;
  • Launch it and scan your computer for files encrypted by Coos ransomware;
  • Restore them.

Recover .coos extension files one by one with Windows Previous Version feature

This feature enables Windows users to bring back the previous version of files, keeping in mind that System Restore was enabled and isn't encrypted.

  • Find an encrypted file you need to restore and right-click on it;
  • Select “Properties” and go to “Previous versions” tab;
  • Here, check each of available copies of the file in “Folder versions”. You should select the version you want to recover and click “Restore”.

Restore data with Shadow Explorer

Shadow Explorer restores data from Shadow Volume Copies. If the infection didn't remove those copies, then Shadow Explorer might restore old files.

  • Download Shadow Explorer (;
  • Follow a Shadow Explorer Setup Wizard and install this application on your computer;
  • Launch the program and go through the drop down menu on the top left corner to select the disk of your encrypted data. Check what folders are there;
  • Right-click on the folder you want to restore and select “Export”. You can also select where you want it to be stored.

Possible decryption methods

There's no decryptor available at the moment, but a company called Emisoft is constantly working on their decryption tools for Djvu family ransomware. It's free, so you can download it and give it a go.

Finally, you should always think about the protection of crypto-ransomwares. In order to protect your computer from Coos and other ransomwares, use a reputable anti-spyware, such as ReimageIntego, SpyHunter 5Combo Cleaner or Malwarebytes

How to prevent from getting ransomware

Protect your privacy – employ a VPN

There are several ways how to make your online time more private – you can access an incognito tab. However, there is no secret that even in this mode, you are tracked for advertising purposes. There is a way to add an extra layer of protection and create a completely anonymous web browsing practice with the help of Private Internet Access VPN. This software reroutes traffic through different servers, thus leaving your IP address and geolocation in disguise. Besides, it is based on a strict no-log policy, meaning that no data will be recorded, leaked, and available for both first and third parties. The combination of a secure web browser and Private Internet Access VPN will let you browse the Internet without a feeling of being spied or targeted by criminals. 

No backups? No problem. Use a data recovery tool

If you wonder how data loss can occur, you should not look any further for answers – human errors, malware attacks, hardware failures, power cuts, natural disasters, or even simple negligence. In some cases, lost files are extremely important, and many straight out panic when such an unfortunate course of events happen. Due to this, you should always ensure that you prepare proper data backups on a regular basis.

If you were caught by surprise and did not have any backups to restore your files from, not everything is lost. Data Recovery Pro is one of the leading file recovery solutions you can find on the market – it is likely to restore even lost emails or data located on an external device.

About the author
Ugnius Kiguolis
Ugnius Kiguolis - The mastermind

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