Koom ransomware (virus) - Decryption Steps Included

Koom virus Removal Guide

What is Koom ransomware?

Koom ransomware encourages people to pay up via _readme.txt file with a ransom demand

Koom ransomwareThe infection starts with the encryption, but it ends with the ransom note delivery

The malicious infection happens silently, but the fact that the Koom ransomware virus can run on the machine before it affects files makes it more persistent. The threat locks data and asks for money, promising to provide the decryption tool after the money transfer. However, that is not a truthful statement because, in most cases, ransomware developers do not provide any help and only focus on their profit.

Koom virus is a ransomware virus that renames files and appends the .koom extension onto each encrypted file's filename. The virus notifies victims by displaying the ransom note file named _readme.txt. The file includes a message from criminals, contact information, information on ransom payments.

The virus is a new, malicious ransomware program that has just been discovered. But it belongs to the ransomware family Djvu that has been known for a while and is actively releasing new versions every week with slightly altered features. One of its main functions appears to be preventing victims from accessing their files by encrypting them and appending the unique extension onto each encrypted file name. When it infects your computer, it will change those file names and alters various other settings to ensure the persistence of the threat.

Name Koom ransomware
Type Cryptovirus, file locker
Family Djvu/STOP ransomware
Appendix .koom appears at the end of every affected file
Ransom note _readme.txt instructs people on the further actions
Ransom amount $980, discount for first 72 hours – $490
Contact information managerhelper@airmail.cc, manager@mailtemp.ch
Distribution Files get distributed with game or software cracks, included as spam email attachments
Removal The best option for the elimination – anti-malware tools that can detect[1] all malicious pieces and remove them
Repair Make sure to scan the machine with ReimageIntego and find any affected parts of data in the system directories

The ransom note provides contact and payment information. It instructs victims to contact the attacker via manager@mailtemp.ch or managerhelper@airmail.cc email address within 72 hours from attack for a decryption tool that costs between $490-$980 depending on how soon they want it done. Additionally, cybercriminals inform their unfortunate captives that it is possible to send an encrypted file for free decryption, but that alone might be dangerous.

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.
You can get and look video overview decrypt tool:
hxxps://we.tl/t-CtDpAM1g5f
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:
manager@mailtemp.ch

Reserve e-mail address to contact us:
managerhelper@airmail.cc

Your personal ID:

We do not recommend contacting criminals at any cost. Experts[2] always note that threat actors behind malware likeKoom ransomware can do things to fake legitimacy and trust between victims and extortionists, so the person whose files are captive would pay more willingly. That is never a good idea.

Possible .Koom file decryption

There are some versions of cryptocurrency-extortion threats that send the malicious files, other infections after the payment transfer for the promised decryption tool. However, the decryption process is not an easy thing. Official decryption tools take time to develop. The already existing decryptor from Emsisoft is partially helpful in such cases, but the success depends on the offline vs. online ID formation factor.

Koom ransomware virusIntruder keeps the machine slow when all the additional processes and file-encryption runs

If you have infected your computer 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 is 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.
    Koom ransomware
  • 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.
    Koom ransomware
  • Press Decrypt.
    Koom ransomware

From here, there are three available outcomes:

  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 files with this tool.

The important step – virus removal

The STOP/Djvu decrypter will stop the ransomware from running so that it can't continue encrypting your files, however, it doesn't completely remove the malware. This is not the same the other way around – anti-malware tools do not recover your files. Most anti-virus software detects malware and its pieces on the machine if you run a scan. You can rely on SpyHunter 5Combo Cleaner or Malwarebytes and check the system thoroughly for all the virus files that need to get terminated.

Note that formatting hard drives and reinstalling with windows again is an option also but not really necessary as there are other apps available too. This threat's damage to the machine consists of affecting the registry, other files, and system directories. Those changes can damage functions further and cause issues with the machine beside the file locking. Eliminate the risk of getting your system damaged, and files encoded again by removing the virus completely.

The thing that concerns people is Koom virus encryption[3] that causes file locking and issues with data recovery. It is common for users to panic and search for any possible file repair option, but anyone can claim to have the needed solution to get your money. The virus removal is more important than the file repair because you need to terminate the infection in the first place before you add any file copies on the machine or use recovery software.

Koom file virusThis type of virus can be eliminated using AV tools

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 ReimageIntego repair. Not only can it fix virus damage after the infection, but it can also remove malware that has already broken into the system thanks to several engines used by the program. Besides, the application can also fix 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 immediatelyReimage scan
  • 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.Reimage results

.koom file recovery

When the ransomware cannot connect to its command and control servers while encrypting your files, it uses a built-in encryption key that matches with all victims of the same variant. This means that every time there is a new variant/extension of the family, the threat goes for an offline ID. With this particular family, of theKoom virus affects machines and uses offline method, everyone who has their data encrypted by the same version will also have access to the decryption. It is possible to use just one specific private key, which could be helpful in situations.

However, the particular versions released after August 2019 mainly use online IDs, and the existing decryption tool is not helpful. The ransomware's ability to connect with command and control servers is a crucial element in its operation of encoding. When it encrypts files, the server responds by generating random keys for each infected computer – meaning that if you want your data back, there are no master keys available anywhere online or on-disk, which would unlock all locks at once.

With older variants, this was manageable as long as they had some help, but newer versions have become increasingly resilient against such efforts. Developers altered their encryption methods and these techniques to ensure persistence and keep the family of Djvu more dangerous. Unfortunately, that leavesKoom ransomware virus victims with fewer options for proper file recovery.

Since the official decryption tools take time to be made, you only can save some of the files alongside malicious pieces and wait for the development, or actions from law enforcement agencies. The family is well-known and dangerous enough to remain undetected. Criminals run their malicious programs for a long time, so rely on alternative options instead.

Unfortunately, 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.

Install data recovery software

  1. Download Data Recovery Pro.
  2. Double-click the installer to launch it.
  3. Follow on-screen instructions to install the software.
  4. As soon as you press Finish, you can use the app.
  5. Select Everything or pick individual folders. Select what to recover
  6. Press Next.
  7. At the bottom, enable Deep scan and pick which Disks you want to be scanned.Select Deep scan
  8. Press Scan and wait till it is complete.Scan
  9. You can now pick which folders/files to recover – don't forget you also have the option to search by the file name!
  10. Press Recover to retrieve your files.Recover files

The system can be damaged significantly, and all the Koom ransomware virus activities might cause more damage than the encryption of files. You can remove the threat with tools like SpyHunter 5Combo Cleaner or Malwarebytes since those AV detection tools are the best for malware termination. However, you also need to think about problems with the system performance and data affected there, so run ReimageIntego for the proper system repair procedures. You can also rely on additional helpful guides below.

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Compatible with Microsoft Windows Compatible with macOS
What to do if failed?
If you failed to fix 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 Koom virus. Follow these steps

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:

Hosts file

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:

C:\\Windows\\System32\\drivers\\etc\\

Delete Windows "hosts" file

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

  1. Download Data Recovery Pro.
  2. Double-click the installer to launch it.
    Launch installer
  3. Follow on-screen instructions to install the software. Install program
  4. As soon as you press Finish, you can use the app.
  5. Select Everything or pick individual folders where you want the files to be recovered from. Select what to recover
  6. Press Next.
  7. At the bottom, enable Deep scan and pick which Disks you want to be scanned. Select Deep scan
  8. Press Scan and wait till it is complete. Scan
  9. You can now pick which folders/files to recover – don't forget you also have the option to search by the file name!
  10. Press Recover to retrieve your files. Recover 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:

  1. Click on the OneDrive icon within your system tray.
  2. Select Help & Settings > Settings.
    Go to OneDrive settings
  3. 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.
    Add OneDrive account
  4. Once done, move to the Backup tab and click Manage backup.
    Manage backup
  5. Select Desktop, Documents, and Pictures, or a combination of whichever folders you want to backup.
  6. Press Start backup.
    Pick which folders to sync

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.

  1. Download the Google Drive app installer and click on it.
    Install Google Drive app
  2. Wait a few seconds for it to be installed. Complete installation
  3. Now click the arrow within your system tray – you should see Google Drive icon there, click it once.
    Google Drive Sign in
  4. Click Get Started. Backup and sync
  5. Enter all the required information – your email/phone, and password. Enter email/phone
  6. Now pick what you want to sync and backup. You can click on Choose Folder to add additional folders to the list.
  7. Once done, pick Next. Choose what to sync
  8. Now you can select to sync items to be visible on your computer.
  9. 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:

Internet Crime Complaint Center IC3

If your country is not listed above, you should contact the local police department or communications center.

Manual removal using Safe Mode

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.
    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.
    Reboot
  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.
    Startup

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
    Downloads
    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):

    %AppData%
    %LocalAppData%
    %ProgramData%
    %WinDir%

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 Koom and other ransomwares, use a reputable anti-spyware, such as ReimageIntego, SpyHunter 5Combo Cleaner or Malwarebytes

How to prevent from getting ransomware

Do not let government spy on you

The government has many issues in regards to tracking users' data and spying on citizens, so you should take this into consideration and learn more about shady information gathering practices. Avoid any unwanted government tracking or spying by going totally anonymous on the internet. 

You can choose a different location when you go online and access any material you want without particular content restrictions. You can easily enjoy internet connection without any risks of being hacked by using Private Internet Access VPN.

Control the information that can be accessed by government any other unwanted party and surf online without being spied on. Even if you are not involved in illegal activities or trust your selection of services, platforms, be suspicious for your own security and take precautionary measures by using the VPN service.

Backup files for the later use, in case of the malware attack

Computer users can suffer from data losses due to cyber infections or their own faulty doings. Ransomware can encrypt and hold files hostage, while unforeseen power cuts might cause a loss of important documents. If you have proper up-to-date backups, you can easily recover after such an incident and get back to work. It is also equally important to update backups on a regular basis so that the newest information remains intact – you can set this process to be performed automatically.

When you have the previous version of every important document or project you can avoid frustration and breakdowns. It comes in handy when malware strikes out of nowhere. Use Data Recovery Pro for the data restoration process.

About the author
Lucia Danes
Lucia Danes - Virus researcher

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References
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