How to remove Ninja ransomware from the operating system?

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

Ninja ransomware removal instructions

What is Ninja?

Discovered by Jakub Kroustek, Ninja is a malicious program, classified as ransomware. It belongs to the Dharma/Crysis malware family. Ninja operates by encrypting data and demanding a ransom for its decryption. During the encryption process, all files are appended with a unique ID (generated individually for each victim), developers' email address and the ".ninja" extension. Therefore, a file like "1.jpg" would appear as something similar to "[].ninja", and so on for all of the 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 of the user's data has been locked and if they wish to retrieve it, they must write to Ninja's developers. The pop-up window is a more detailed ransom note. It informs victims of the encryption and tells them that if they wish to decrypt their data, they are to use the listed email addresses. If the cyber criminals do not reply in 24 hours, there is an alternative email address provided. The user's letter must contain their ID (written in every encrypted file's filename and in the pop-up's message) in the title/subject field. The price of the decryption tools/software (ransom) is not stated, however it will supposedly depend on how quickly the victim establishes contact. Bitcoin cryptocurrency is what the criminals demand the payment be made in. For this purpose, there are links given, which have instructions on how to acquire Bitcoins. After the ransom is paid, the user is promised decryptions tools, which will restore their data. As proof that data recovery is possible, free decryption of one file is offered. This test file must be no larger than 1Mb and contain no valuable information (e.g. database, backup, large excel sheet, etc.). The note concludes with warnings. They alert the victim that renaming the encrypted files and attempting manual decryption with third party software - will result in permanent data loss. Unfortunately, it is true that in most cases of ransomware infections manual decryption is impossible. Typically, only the program used to encrypt the files - can decrypt them. Despite this, it is strongly advised against communicating with and/or meeting demands of cyber criminals. Often, even though victims pay - they do not receive the necessary tools/software and their data remains essentially worthless. While removing Ninja will not restore the affected files, removal will prevent it from further encryptions. The only possible solution is recovering 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

PeetMajor2HamlampampomM3g4c0rtx are a few examples of other malware, 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 transactions of such are difficult/impossible to trace. Unless a certain ransomware is still in development and/or has key flaws/bugs, decryption without the involvement of its developers is impossible. It is advised to keep backups in 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 types of malware) is primarily spread through trojans, spam campaigns, untrustworthy download sources, fake software updaters and "cracking" (activation) tools. Trojans are a type of malware, designed to cause chain infections. Massive scale spam campaigns are used to send out deceptive emails with infectious attachments (or contain links leading to virulent files). This mail is often labeled as "official", "important", "priority" and 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 considered to be untrustworthy. Download channels of this kind are more likely to offer malware disguised as regular products and/or content bundled with it. Fraudulent updaters infect systems by exploiting flaws of outdated software or by installing malware instead of updates. Illegal activation tools ("cracks") cause infections in a similar manner, by downloading/installing malicious programs rather than activating licensed product.

Threat Summary:
Name Ninja virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .ninja (encrypted filed are also appended with unique ID and developers' 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.

To eliminate Ninja 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?

Suspicious/Irrelevant emails should not be opened, especially ones received from unknown senders. Attachments (and links) found in them - must never be opened, as these files are the source of a potential system infection. It is advised to only use official and verified download channels. Program activation and updating is to be done with tools/functions provided by legitimate developers; illegal activation ("cracking") tools and third party downloaders and deemed to be high-risk, therefore should not be used. It is highly recommended to have a 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 Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Ninja ransomware's 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's 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 removal of Ninja 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 Ninja 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 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 virus and spyware 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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Platform: Windows

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