King Ouroboros Ransomware

Also Known As: King Ouroboros virus
Distribution: Low
Damage level: Severe

King Ouroboros ransomware removal instructions

What is King Ouroboros?

First discovered by Michael Gillespie, King Ouroboros is a ransomware-type virus based on an open-source ransomware project called CryptoWire. Immediately after infiltration, King Ouroboros encrypts stored data using the AES-256 encryption algorithm. Furthermore, it renames compromised data using the "[original_name].king_ouroboros.[original_format]" pattern. For example, "sample.jpg" is renamed to "sample.king_ouroboros.jpg". Once data is encrypted, using it immediately becomes impossible. After successfully encrypting data, King Ouroboros opens a pop-up window containing a ransom-demand message. Updated variants of this ransomware use "[].Lazarus" extension for encrypted files.

The message essentially states that data is compromised and that the victim must pay a ransom to restore it. As mentioned above, King Ouroboros uses AES (a symmetric encryption algorithm) that employs an identical key to encrypt and decrypt data. Each victim receives a unique key, however, developers hide all keys on a remote server. Therefore, since restoring files without a key is impossible, users are encouraged to pay a ransom of $50 in Bitcoins for their release. The message also states that the ransom must be paid within 72 hours, otherwise keys are permanently deleted. As compared to other ransomware, this cost is quite low - most demand $500-1500. Despite this, you should not pay. Research shows that ransomware developers are likely to ignore victims, once payments are submitted. Therefore, paying typically gives no positive result and users are scammed. All requests to pay ransoms should be ignored. Unfortunately, there are no tools capable of cracking AES cryptography and restoring data free of charge. The only solution is to restore everything from a backup.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:


There are dozens of ransomware-type viruses similar to King Ouroboros. BtcKING, Omerta, and Leen - these are just some examples from many. Note that although these viruses are developed by different cyber criminals, their behavior is identical - all encrypt data and make ransom demands. The size of ransom and type of encryption are often the only major differences. These viruses typically employ algorithms that generate unique decryption keys. Therefore, unless the virus is not fully developed or has certain bugs/flaws, decrypting data without developer involvement is impossible. These viruses present a strong case for maintaining regular data backups. Bear in mind, however, that backups can be encrypted as well. Therefore, to prevent this situation, store backups on a remote server (e.g., Cloud) or an unplugged storage device (Flash drive, external hard drive or similar).

How did ransomware infect my computer?

Cyber criminals typically proliferate ransomware using trojans, fake software updaters, P2P (peer-to-peer) networks (eMule, torrents, and so on), unofficial download sources (free file hosting websites, freeware download websites, etc.), and spam emails (malicious attachments). Trojans are probably the simplest, since most are designed to open "backdoors" for other viruses to infiltrate the system. Fake update tools infect the system by exploiting outdated software bugs/flaws or simply downloading and installing malware rather than updates. P2P networks and other third party download sources proliferate malware by presenting it as legitimate software. Users are tricked into downloading and installing malware. Infectious attachments typically come in the format of JavaScript files or MS Office documents. Once opened, these files stealthily download and install malware.

Threat Summary:
Name King Ouroboros virus
Threat Type Ransomware, Crypto Virus, Files locker
Symptoms Can't open files stored on your computer, previously functional files now have a different extension, for example my.docx.locked. A ransom demanding message is displayed on your desktop. Cyber criminals are asking to pay a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password stealing trojans and malware infections can be installed together with a ransomware infection.

To eliminate King Ouroboros virus our malware researchers recommend scanning your computer with Spyhunter.
▼ Download Spyhunter
Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

How to protect yourself from ransomware infections?

The main reasons for computer infections are poor knowledge and careless behavior. The key to safety is caution. Therefore, pay close attention when browsing the Internet and downloading/updating/installing software. Think twice before opening email attachments. Files that seem irrelevant or have been received from a suspicious email address should never be opened. It is also important to download your programs from official sources only (via direct download links) rather than using third party downloaders/installers. These tools are used to proliferate rogue programs, and thus should never be used. The same rule should be applied for software updates. Keep installed programs up-to-date using implemented functions or tools provided by the official developer only. Having a legitimate anti-virus/anti-spyware suite installed and running is also paramount. If your computer is already infected with King Ouroboros, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in King Ouroboros ransomware text file :

The only way you can recover your files is to buy a decryption key
The payment method is: Bitcoin. The price is: $50 = 0.00750331 Bitcoins
After buying the amount of bitcoins send an email
to Your ID: 512064768
We will provide you with payment address and your decryption key.
You have 72 Hours to complete the payment otherwise your key will be deleted.

Image set as victim's desktop wallpaper:

KING-OUROBOROS ransomware desktop wallpaper

Screenshot of files encrypted by King Ouroboros ("[original_name].king_ouroboros.[original_format]" filename pattern):

Files encrypted by King Ouroboros

KING_OUROBOROS ransomware developers are concerned (message on Twitter) that our article questions if Cyber criminals responsible for this ransomware actually decrypt the victims files after the payment:

KING OUROBOROS twitter message

King Ouroboros ransomware removal:

Instant automatic removal of King Ouroboros virus: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Spyhunter is a professional automatic malware removal tool that is recommended to get rid of King Ouroboros virus. Download it by clicking the button below:
▼ DOWNLOAD Spyhunter By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. Free scanner checks if your computer is infected. To remove malware, you have to purchase the full version of Spyhunter.

Quick menu:

Step 1

Windows XP and Windows 7 users: Start your computer in Safe Mode. Click Start, click Shut Down, click Restart, click OK. During your computer start process, press the F8 key on your keyboard multiple times until you see the Windows Advanced Option menu, and then select Safe Mode with Networking from the list.

Safe Mode with Networking

Video showing how to start Windows 7 in "Safe Mode with Networking":

Windows 8 users: Start Windows 8 is Safe Mode with Networking - Go to Windows 8 Start Screen, type Advanced, in the search results select Settings. Click Advanced startup options, in the opened "General PC Settings" window, select Advanced startup. Click the "Restart now" button. Your computer will now restart into the "Advanced Startup options menu". Click the "Troubleshoot" button, and then click the "Advanced options" button. In the advanced option screen, click "Startup settings". Click the "Restart" button. Your PC will restart into the Startup Settings screen. Press F5 to boot in Safe Mode with Networking.

Windows 8 Safe Mode with networking

Video showing how to start Windows 8 in "Safe Mode with Networking":

Windows 10 users: Click the Windows logo and select the Power icon. In the opened menu click "Restart" while holding "Shift" button on your keyboard. In the "choose an option" window click on the "Troubleshoot", next select "Advanced options". In the advanced options menu select "Startup Settings" and click on the "Restart" button. In the following window you should click the "F5" button on your keyboard. This will restart your operating system in safe mode with networking.

windows 10 safe mode with networking

Video showing how to start Windows 10 in "Safe Mode with Networking":

Step 2

Log in to the account infected with the King Ouroboros virus. Start your Internet browser and download a legitimate anti-spyware program. Update the anti-spyware software and start a full system scan. Remove all entries detected.

If you cannot start your computer in Safe Mode with Networking, try performing a System Restore.

Video showing how to remove ransomware virus using "Safe Mode with Command Prompt" and "System Restore":

1. During your computer start process, press the F8 key on your keyboard multiple times until the Windows Advanced Options menu appears, and then select Safe Mode with Command Prompt from the list and press ENTER.

Boot your computer in Safe Mode with Command Prompt

2. When Command Prompt mode loads, enter the following line: cd restore and press ENTER.

system restore using command prompt type cd restore

3. Next, type this line: rstrui.exe and press ENTER.

system restore using command prompt rstrui.exe

4. In the opened window, click "Next".

restore system files and settings

5. Select one of the available Restore Points and click "Next" (this will restore your computer system to an earlier time and date, prior to the King Ouroboros ransomware virus infiltrating your PC).

select a restore point

6. In the opened window, click "Yes".

run system restore

7. After restoring your computer to a previous date, download and scan your PC with recommended malware removal software to eliminate any remaining King Ouroboros ransomware files.

To restore individual files encrypted by this ransomware, try using Windows Previous Versions feature. This method is only effective if the System Restore function was enabled on an infected operating system. Note that some variants of King Ouroboros are known to remove Shadow Volume Copies of the files, so this method may not work on all computers.

To restore a file, right-click over it, go into Properties, and select the Previous Versions tab. If the relevant file has a Restore Point, select it and click the "Restore" button.

Restoring files encrypted by CryptoDefense

If you cannot start your computer in Safe Mode with Networking (or with Command Prompt), boot your computer using a rescue disk. Some variants of ransomware disable Safe Mode making its removal complicated. For this step, you require access to another computer.

To regain control of the files encrypted by King Ouroboros, you can also try using a program called Shadow Explorer. More information on how to use this program is available here.

shadow explorer screenshot

To protect your computer from file encryption ransomware such as this, use reputable antivirus and anti-spyware programs. As an extra protection method, you can use programs called HitmanPro.Alert and EasySync CryptoMonitor, which artificially implant group policy objects into the registry to block rogue programs such as King Ouroboros ransomware.

Note that Windows 10 Fall Creators Update includes a "Controlled Folder Access" feature that blocks ransomware attempts to encrypt your files. By default, this feature automatically protects files stored in the Documents, Pictures, Videos, Music, Favorites as well as Desktop folders.

Controll Folder Access

Windows 10 users should install this update to protect their data from ransomware attacks. Here is more information on how to get this update and add an additional protection layer from ransomware infections.

HitmanPro.Alert CryptoGuard - detects encryption of files and neutralises any attempts without need for user-intervention:

hitmanproalert ransomware prevention application

Malwarebytes Anti-Ransomware Beta uses advanced proactive technology that monitors ransomware activity and terminates it immediately - before reaching users' files:

malwarebytes anti-ransomware

  • The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups. More information on online backup solutions and data recovery software Here.

Other tools known to remove King Ouroboros ransomware:

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global virus and spyware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
King Ouroboros virus QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of King Ouroboros virus on your mobile device.
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Platform: Windows

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