Kjh Ransomware

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

Kjh ransomware removal instructions

What is Kjh?

First discovered by Jakub Kroustek, Kjh is high-risk ransomware belonging to the Dharma ransomware family. Immediately after infiltration, Kjh encrypts most stored data, thereby rendering files unusable. Additionally, Kjh appends filenames with the ".kjh" extension plus the victim's unique ID and developer's email address. For example, "sample.jpg" might be renamed to a filename such as "sample.jpg.id-1E857D00.[datareturn@protonmail.com].kjh". Kjh then opens a pop-up window and stores the "RETURN FILES.txt" text file on the desktop.

The new text file contains a short message stating that data is encrypted and that victims must contact Kjh's developers if they want to restore their files. The pop-up, on the other hand, provides much more information. It states that data is encrypted and that decryption requires a unique key. Unfortunately, this information is accurate. According to the pop-up, Kjh encrypts data using RSA-1024 algorithm. This cryptography is asymmetric and, thus, two unique keys (public [encryption] and private [decryption]) are created for each victim. Restoring data without the private key is impossible. Furthermore, cyber criminals have no access to their keys, since they are stored on a remote server controlled by cyber criminals. Thus, victims who wish to decrypt their data must purchase a decryption tool with the key embedded within. The cost is not specified - all details are provided via email, however, size of ransom usually fluctuates between $500 and $1500. Additionally, ransoms must be paid using cryptocurrencies. Regardless of the cost, do not pay. Research shows that cyber criminals typically ignore victims, once payments are submitted. Therefore, we strongly advise you to ignore all requests to submit payments or even contact these people. Unfortunately, Kjh is undecryptable ransomware - there are no tools capable of cracking RSA-1024 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:

Kjh decrypt instructions

There are hundreds of ransomware infections, all of which are very similar. The list of examples includes DDTHerosetge0l0gic, and many others. Most of these infections encrypt data so that cyber criminals are able to make ransom demands by offering paid decryption. Research shows that infections of this type usually encrypt data using RSA, AES, and other cryptographies that generate unique decryption keys. Therefore, decryption without developers' involvement is impossible unless the malware is not fully developed or has certain bugs/flaws. Ransomware infections present a strong case for maintaining regular backups. Bear in mind, however, that locally stored backups can be compromised with regular data. Therefore, we strongly advise you to store them on a remote server or unplugged storage device. Additionally, have multiple backup copies stored different locations, since there is always a chance that servers and storage devices can be damaged.

How did ransomware infect my computer?

To proliferate ransomware, criminals often use third party software download sources, spam email campaigns, trojans, and fake software updaters/cracks. Unofficial software download sources (such as freeware download websites, free file hosting sites, Peer-to-Peer [P2P]) are used to proliferate malware by presenting it as legitimate software). Criminals trick users into  manuallydownloading and installing malware. Spam campaigns are also used in a similar manner. Criminals send hundreds of thousands of emails that contain malicious attachments, and deceptive messages encouraging recipients to open them. To give the impression of legitimacy, criminals often present attachments as important documents (e.g., bills, invoices, receipts, etc.). Trojans are malicious applications that stealthily infiltrate computers by downloading and installing malware. Fake updaters infect systems by exploiting outdated software bugs/flaws or simply downloading and installing malware rather than updates. Finally, fake 'cracks' stealthily download/install malware rather than giving access to paid features. In summary, the main reasons for computer infections are poor knowledge of these threats and careless behavior.

Threat Summary:
Name Kjh virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .kjh (this ransomware also appends filenames with the developer's email address).
Ransom Demanding Message Pop-up window, RETURN FILES.txt text file.
Cyber Criminal Contact datareturn@protonmail.com, returndata@airmail.cc
Detection Names Avast (Win32:RansomX-gen [Ransom]), BitDefender (Trojan.Ransom.Crysis.E), ESET-NOD32 (A Variant Of Win32/Filecoder.Crysis.P), Kaspersky (Trojan-Ransom.Win32.Crusis.to), 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?

Handle each email attachment with care. Files/links that are irrelevant and those received from suspicious/unrecognizable email addresses should never be opened. Software should be downloaded from official sources only, using direct download links. Third party downloaders/installers often include rogue apps and, thus these tools should not be used. Installed applications and operating systems should be kept updated. This should be achieved only through implemented functions or tools provided by the official developer. Be aware that software piracy is a cyber crime and the risk of infection is extremely high. Therefore, never attempt to crack installed applications. Have a reputable anti-virus/anti-spyware suite installed and running at all times - this will detect and eliminate malware before it damages the system. The key to computer safety is caution. If your computer is already infected with Kjh, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text presented in Kjh ransomware text file :

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.)
When you make sure of decryption possibility transfer the money to our bitcoin wallet. As soon as we receive the money we will send you:
1. Decryption program.
2. Detailed instruction for decryption.
3. And individual keys for decrypting your files.
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 Kjh text file ("RETURN FILES.txt"):

Kjh text file

Text presented within this file:

All your data is encrypted!
for return write to mail:
datareturn@protonmail.com, returndata@airmail.cc

Screenshot of files encrypted by Kjh (".kjh" extension):

Files encrypted by Kjh

Kjh 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 Kjh 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 Kjh 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 Kjh 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 Kjh 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 Kjh, 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 Kjh 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 Kjh 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 pcrisk.com 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 malware activity level today:

Medium threat activity

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

QR Code
Kjh 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 Kjh virus on your mobile device.
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