How to remove Ninja ransomware from your operating system

Also Known As: Ninja virus
Distribution: Low
Damage level: Severe

Ninja ransomware removal instructions

What is Ninja?

Discovered by Jakub Kroustek and belonging to the Dharma/Crysis malware family, Ninja is a malicious program classified as ransomware. Ninja operates by encrypting data and demanding ransom payments for decryption. During the encryption process, all files are appended with a unique ID (generated individually for each victim), the developer's email address, and the ".ninja" extension. Therefore, "1.jpg" might appear as a filename similar to "[].ninja" and so on for all compromised files. Once this process is finished, a text file ("FILES ENCRYPTED.txt") is created on the desktop and a pop-up window is displayed.

The text file contains a message stating that all data has been locked and, if users wish to retrieve it, they must send a message to Ninja's developers. The pop-up window is a more detailed ransom message. It informs victims of the encryption and instructs them that, if they wish to decrypt their data, they must use the email addresses listed. If the cyber criminals do not reply within 24 hours, an alternative email address is provided. The victims's message must contain the ID (provided within the filename of each encrypted file and in the pop-up message) in the title/subject field. The cost of decryption tools/software (ransom) is not stated, however, this will supposedly depend on how quickly the victim establishes contact. The Bitcoin cryptocurrency is often stipulated by criminals for payments to be made. For this purpose, links are given, which include instructions about how to acquire Bitcoins. After the ransom is paid, users are promised decryption tools, which will apparently restore their data. As 'proof' that data recovery is possible, free decryption of one file is offered. This test file must not exceed 1 MB and contain no valuable information (e.g. databases, backups, large excel sheets, etc.). The message concludes with various warnings, which alert the victim that renaming the encrypted files and manual decryption with third party software will result in permanent data loss. Unfortunately, in most cases of ransomware infections, manual decryption is impossible. Typically, only the program used to encrypt the files can decode them. Despite this, you are strongly advised against communicating with and/or meeting the demands of cyber criminals. Although some victims pay, they receive none of the necessary tools/software and their data remains essentially useless. While removing Ninja will not restore affected files, it will prevent further encryption. The only solution is to recover the data from a backup, if one was made prior to the attack and was stored separately.

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

Ninja decrypt instructions

PeetMajor2Hamlampampom, and M3g4c0rtx are just some examples of other malware infections similar to Ninja. All ransomware is designed to encrypt data and demand payment for decryption tools/software. Crucial differences include the cryptographic algorithm they use (symmetric or asymmetric) and the ransom size. These sums usually range between thee and four digits (in USD). Digital currencies (mostly cryptocurrencies) are preferred by cyber criminals, as these transactions are difficult/impossible to trace. Unless ransomware is still in development and/or has certain flaws/bugs, decryption without the involvement of its developers is impossible. You are advised to keep backups on remote servers and/or unplugged storage devices to ensure data safety. Ideally, multiple backups should be stored in different locations.

How did ransomware infect my computer?

Malicious content (ransomware and other malware) is primarily spread through trojans, spam campaigns, untrustworthy download sources, fake software updaters and "cracking" (activation) tools. A Trojans is a type of malware infection designed to cause chain infections. Massive scale spam campaigns are used to send out deceptive emails with infectious attachments (or containing links leading to dangerous files). This mail is often labelled as "official", "important", "priority" or similar. The attachments can be in various formats (e.g. archive and executable files, Microsoft Office and PDF documents, JavaScript, etc.). Once opened, they initiate the infection process (i.e., download/install malicious programs). Unofficial and free file-hosting websites, P2P sharing networks (BitTorrent, eMule, Gnutella, etc.) and other third party downloaders are classed as untrustworthy. These download channels are more likely to offer malware disguised as regular products and/or content bundled with it. Fake updaters infect systems by exploiting flaws of outdated software or by installing malware rather than updates. Illegal activation tools ("cracks") cause infections in a similar manner, by downloading/installing malicious programs rather than activating licensed products.

Threat Summary:
Name Ninja virus
Threat Type Ransomware, Crypto Virus, Files locker.
Encrypted Files Extension .ninja (encrypted filed are also appended with a unique ID and the developer's email address).
Ransom Demanding Message FILES ENCRYPTED.txt and pop-up window.
Cyber Criminal Contact and
Detection Names BitDefender (Trojan.Ransom.Crysis.E), ESET-NOD32 (A Variant Of Win32/Filecoder.Crysis.P), Emsisoft (Trojan.Ransom.Crysis.E (B)), McAfee (Ransom-Dharma!D52DB0915AF4), Full List Of Detections (VirusTotal)
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of 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.
Malware Removal (Windows)

To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Malwarebytes.
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How to protect yourself from ransomware infections

Suspicious/Irrelevant emails should not be opened, especially those received from unknown senders. Do not open attachments or links found in them, as these files are the source of a potential system infection. Use only official and verified download channels. Program activation and updating should be performed with tools/functions provided by legitimate developers. Illegal activation ("cracking") tools and third party downloaders are high-risk, and therefore should not be used. Have reputable anti-virus/anti-spyware software installed and kept up-to-date. These products should be used to perform regular system scans and for the elimination of detected threats. If your computer is already infected with Ninja, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text presented in Ninja ransomware pop-up window:

All your files have been encrypted!
All your files have been encrypted due to a security problem with your PC. If you want to restore them, write us to the e-mail
Write this ID in the title of your message 1E857D00
In case of no answer in 24 hours write us to theese
You have to pay for decryption in Bitcoins. The price depends on how fast you write to us. After payment we will send you the decryption tool that will decrypt all your files.
Free decryption as guarantee
Before paying you can send us up to 1 file for free decryption. The total size of files must be less than 1Mb (non archived), and files should not contain valuable information. (databases,backups, large excel sheets, etc.)
How to obtain Bitcoins
The easiest way to buy bitcoins is LocalBitcoins site. You have to register, click 'Buy bitcoins', and select the seller by payment method and price.
Also you can find other places to buy Bitcoins and beginners guide here:
Do not rename encrypted files.
Do not try to decrypt your data using third party software, it may cause permanent data loss.
Decryption of your files with the help of third parties may cause increased price (they add their fee to our) or you can become a victim of a scam. 

Screenshot of Ninja text file ("FILES ENCRYPTED.txt"):

Ninja text file

Text presented in this file:

all your data has been locked us
You want to return?
write email or 

Screenshot of files encrypted by Ninja (".ninja" extension):

Files encrypted by Ninja

Ninja ransomware removal:

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Malwarebytes is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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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 Ninja 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 Ninja 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 Ninja 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 Ninja 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 Ninja, 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 Ninja 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, and 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 Ninja 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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Removal Instructions in other languages
Malware activity

Global malware activity level today:

Medium threat activity

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

QR Code
Ninja 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 Ninja virus on your mobile device.
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