What is Koobn ransomware?
Koobn is a newly-emerged cyberthreat that runs on Windows computers. This virus uses strong encryption algorithms to make data useless on the infected system. It affects commonly used data such as pictures, documents, videos, databases, and archives. To regain data access, victims need to have a special key which of course is not free. Nonetheless, we still do not recommend you to pay them money, because no one can ensure that cybercriminals keep their promises. You may follow this guide to remove Koobn ransomware and decrypt .koobn files for free.
The content of ransom note (7CYT_HOW_TO_DECRYPT.txt):
Your network has been breached and all data were encrypted.
Personal data, financial reports and important documents are ready to disclose.
To decrypt all the data and to prevent exfiltrated files to be disclosed at
you will need to purchase our decryption software.
Please contact our sales department at:
To get an access to .onion websites download and install Tor Browser at:
hxxps://www.torproject.org/ (Tor Browser is not related to us)
Follow the guidelines below to avoid losing your data:
– Do not modify, rename or delete *.key.koobn files. Your data will be
– Do not modify or rename encrypted files. You will lose them.
– Do not report to the Police, FBI, etc. They don’t care about your business.
They simply won’t allow you to pay. As a result you will lose everything.
– Do not hire a recovery company. They can’t decrypt without the key.
They also don’t care about your business. They believe that they are
good negotiators, but it is not. They usually fail. So speak for yourself.
– Do not reject to purchase. Exfiltrated files will be publicly disclosed.
Once encryption is done, all user’s files will be appended with complex extension: .[random_characters].koobn. For example, file “IMG2054.jpg” will turn into “IMG2054.jpg.eiIZ7Mio4ZN1Jp55iKjeRGir8QNGGVc8oEdwJplOOHf_mwWz_OGsrdM0.koobn“. Afterward, the ransomware will drop a text file with a ransom note – “7CYT_HOW_TO_DECRYPT.txt” that contains kidnappers’ demands. While the text in the ransom note may vary, the essence remains the same – cybercriminals demand money from victims in BTC cryptocurrency to regain data access. However, we do not recommend you do this, because no one can ensure that they send you the decryption tool even if the payment is transferred.
Screenshot of encrypted by Koobn virus files:
There are two solutions to remove Koobn Ransomware and decrypt your files. The first is to use an automated removal tool. This method is suitable even for inexperienced users since the removal tool can delete all instances of the virus in just a few clicks. The second is to use the Manual Removal Guide. This is a more complex way that requires special computer skills.
How Koobn ransomware gets on my computer?
Cybercriminals use various techniques to deliver the virus to the target computer. Ransomware viruses can infiltrate victims’ computers more than in one or two ways, in most cases, cryptoviral extortion attack is carried out with the help of the following methods:
- This is the most used distribution method. Cybercriminals use fraudulent emails to pose as official organizations or business companies (receipts, winning notifications, confirmation of order; bank messages, and so on) to lure unsuspecting users into clicking on a malicious attachment – just one click to make your files inaccessible. To mislead the user and make it look like an official email, cybercriminals add an extra symbol to the email address, for example, instead of firstname.lastname@example.org, you may see service[.]@paypal.com or service[_]@paypal.com. That’s why you should always pay attention to received emails and identify the sender to make sure that this is from a trusted source. Also, the presence of grammatical and typographical errors in the text of the message indicates that this is fake. If nothing’s wrong, scan the attachment with antivirus software first and then you can open it. Compliance with all these rules will help you save a lot of nerve, time, and money.
- Hackers use the special toolkit to exploit known vulnerabilities in systems or applications. That’s why you should always make Windows updates on time and keep them up to date. Remember that these updates close the security holes in the system through which the virus can enter your computer. Make sure that your operating system itself is not outdated and is officially supported, for example, Windows XP, Vista, 7 are no longer supported.
- Various dubious web-sources can contain malicious scripts or hyperlinks that can infect your system. Our advice – avoid visiting P2P sites and websites with illegal content (pirated software, movies, music). Use only legitimate services and remember – there’s no free lunch in this world.
- Cybercriminals often abuse the built-in Windows feature – Remote Desktop Protocol to infect computers with ransomware. That way, they access the target computer remotely and install viruses manually. To avoid infection via RDP, you should set a different from 3389 TCP port and use a more strong password.
|Type of threat||Ransomware, cryptovirus, file-locking virus|
|Contact||onion website (Tor browser)|
|Distribution||Spam email attachments, RDP, pirated software, torrent websites, phishing sites|
In order to completely remove ransomware from your computer, you will need to install an antivirus software. We recommend using SpyHunter
The only effective method to restore files is to copy them from a saved backup. If you don’t have a suitable backup, you may use third-party recovery software such as Stellar Data Recovery
How to remove Koobn ransomware?
Try Stellar Data Recovery
Stellar Data Recovery is one of the most effective tools that can recover lost and corrupted files — documents, emails, pictures, videos, audio files, and more — on any Windows device. The powerful scan engine can detect compromised files and finally save them to specified destination. Despite its advancedness, it’s very concise and simple so that even the most inexperienced user can figure it out.
Email security is the first line of defense against ransomware viruses. To do this, we recommend that you use MailWasher. MailWasher blocks ransomware viruses coming through spam and phishing, and automatically detects malicious attachments and URLs. In addition, malicious messages can be blocked even before the recipient opens them. Since the main source of the spread of ransomware viruses are infected emails, antispam significantly reduces the risk of a virus appearing on your computer.
After the virus is completely removed from your system, you can already start restoring your files directly.
How to decrypt files infected by Koobn Ransomware?
Method 1. Restore your files with the help of Recovery Tool
In case your PC has been attacked by ransomware, you may restore your files by using file recovery software. Stellar Data Recovery is one of the most effective tools that can recover lost and corrupted files — documents, emails, pictures, videos, audio files, and more — on any Windows device. The powerful scan engine can detect compromised files and finally save them to specified destination. Despite its advancedness, it’s very concise and simple so that even the most inexperienced user can figure it out.
- Run Stellar Data Recovery.
- Select type of files you want to restore and click Next.
- Select the drive and folder where your files are located and date that you want to restore them from and press Scan.
- Once the scanning process is done, click Recover to restore your files.
- After this, select a destination and click Start Saving to save restored data.
Since new ransomware-type viruses appear almost every day, there is no technical possibility to issue a decryptor for each virus. In this case, the recovery tool comes to the rescue. Despite the fact that this is one of the most effective methods in the absence of a decryptor, this is not 100 percent and not the only way.
Method 2. Restore the system using System Restore
Although the latest versions of Koobn Ransomware can remove system restore files, this method may help you partially restore your files. Give it a try and use standard System Restore to revive your data. The entire process is preferably carried out in Safe Mode with Command Prompt:
For Windows XP/Vista/7 users:
Restart your computer and before your system starts – hit F8 several times. This will prevent system from loading and will show Advanced boot options screen. Choose Safe mode with Command Prompt option from the options list using up and down arrows on your keyboard and hit Enter.
For Windows 8/10 users:
- Click the Start button, then select Settings
- Click Update & Security, then select Recovery and click Restart now.
- After your device reboots, go to Troubleshoot > Advanced options >Startup Settings > Restart
- After your PC restarts, you should press F5 key to Enable Safe Mode with Command Prompt.
After the system is loaded in Safe Mode with Command Prompt, do following:
- In the Command Prompt window, type cd restore and hit Enter.
- Then type rstrui.exe and hit Enter again.
- Once a new window shows up, click Next.
- Choose the date before the infection appearance and click Next again
- In the opened pop-up window, click Yes to start system restore.
Method 4. Roll the files back to the previous version
Previous versions can be copies of files and folders created by Windows Backup (if it is active) or copies of files and folders created by System Restore. You can use this feature to restore files and folders that you accidentally modified or deleted, or that were damaged. This feature is available in Windows 7 and later versions.
- Click the encrypted file and choose Properties
- Open the Previous Version tab
- Select the latest version and click Copy
- Click Restore
How to prevent your system from Ransomware?
No one is safe from infection with a virus that secretly encrypts your data. But in order to minimize this risk, you need to follow the rules:
1. Always make Windows updates on time and keep them up to date. Remember that these updates close the security holes in the system through which the virus can enter your computer.
2. The most efficient way to avoid data loss is of course to make a backup of all important data from your computer. It is enough just to synchronize the necessary folders with one of the cloud services, so as not to be afraid to see the text requiring the payment of bitcoins in exchange for a decryption key. It can be a cloud or a remote hard drive on the network. If you store all your files on the Internet, the likelihood of virus infection will be lower. Do not make copies to external hard drives, as this could damage them.
3. Since spam email is the most popular form of spreading ransomware-type viruses, the user should never open email attachments without first having scanned them with antivirus. Just clicking on the link or opening the attachment can damage the operating system (Windows) in a few minutes, damage important data, and infect other machines with the virus.
3. Ransomware-type viruses often crawl into a system using the Remote Desktop Protocol (RDP). RDP is a legitimate and useful feature that allows a user to take control of a remote computer or virtual machine over a network connection. But, at the same time, this is its Achilles’ heel as it’s poorly secured and has many vulnerabilities that can give hackers easy entry into the victim’s computer. In this case, we advise you to set a different from 3389 TCP port and use a more strong password. You can additionally protect yourself from virus penetration through an RDP connection with the help of a reliable firewall such as GlassWire’s Firewall
5. All previous methods do not matter if you do not have a reliable antivirus. The presence of anti-virus protection on your computer can prevent all these unpleasant surprises. Anti-virus protection will protect you from malware, money loss, time loss, invasion of your personal life. Now the antivirus market is so huge that it is difficult to make a choice in favor of one of them. If you have not decided who to give preference to, we suggest you familiarize yourself with our Top 5 Antivirus Software for Windows
Written by Ilyas J