Jack Ransomware

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

Jack ransomware removal instructions

What is Jack?

Jack is high-risk ransomware that belongs to a family of ransomware infections called Dharma. This malware was first discovered by cyber security researcher, Jakub Kroustek. After successful infiltration, Jack encrypts most stored data and appends filenames with the ".jack" extension plus the victim's unique ID and developer's email address. Therefore, "sample.jpg" might be renamed to a filename such as "sample.jpg.id-1E857D00.[lockhelp@qq.com].jack". In addition to encrypting data, Jack stores the "RETURN FILES.txt" text file on the desktop and opens a pop-up window.

The new text file contains a short message simply stating that data is encrypted and that victims must contact cyber criminals via the email address provided. The pop-up, on the other hand, provides a bit more information. It also states that files are encrypted and that the victim must contact cyber criminals to restore them, however, the message also specifies that decryption requires a unique key, which is unfortunately accurate. It is stated that data is encrypted using RSA-1024 cryptography, which is asymmetric. If this is the case, each victim gets a unique decryption key (also known as a private key) which is necessary to restore data. Victims cannot access their keys, since developers store them on a remote server. The message states that to receive their keys and restore data, each victim must pay a ransom. It is also stated that this must be paid within seven days after encryption, otherwise the keys are permanently deleted (overwritten by other people's keys). The exact cost is not specified. All payment details are provided via email, however, size of ransom usually fluctuates between $500 and $1500, and criminals ask users to submit payments using Bitcoin, Monero, Ethereum, or other cryptocurrencies. Cyber criminals also offer free decryption of one file (up to 1 MB, non-archived) as a 'guarantee' that recovery is impossible and that these people can be trusted. Be aware, however, that these criminals often ignore victims, once payments are submitted. Therefore, paying typically gives no positive result and users are simply scammed. Unfortunately, Jack is undecryptable ransomware and there are no tools capable of cracking its encryption and restoring data free of charge. You can only restore everything from a backup, if one has been created.

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

Jack decrypt instructions

There are hundreds of ransomware-type infections that share similarities with Jack (e.g., SYSTEM FAILURE, Bufas, Qbtex, etc.). As with Jack, most ransomware infections encrypt data so that developers can make ransom demands. These infections typically employ cryptographies (e.g., RSA, AES, etc.) that generate unique decryption keys. Therefore, unless the ransomware is still in development or has certain bugs/flaws, restoring data manually without involvement of developers (contacting these people is not recommended) is virtually impossible. Infections such as Jack present a strong case for maintaining regular data backups, however, store them on a remote server or unplugged storage device, since locally stored backups will probably be encrypted with regular data. You are also advised to have multiple backup copies stored in different locations, in case the storage device/server is damaged.

How did ransomware infect my computer?

To proliferate ransomware infections, developers often use trojans, fake software updaters/cracks, spam email campaigns, and third party software download sources. Trojans are essentially malicious applications that stealthily infiltrate computers and download/install additional malware. Fake updaters typically infect computers by exploiting outdated software bugs/flaws or simply downloading and installing malware rather than updates. Fake cracks are also similar to fake updaters. Rather than providing access to paid features, fake cracks inject malware into the system. Spam email campaigns deliver hundreds of thousands of emails consisting of malicious attachments (links/files) and deceptive messages encouraging users to open them. To give the impression of legitimacy and trick users into opening them, cyber criminals often present malicious attachments as important documents (e.g., bills, invoices, receipts, etc.). Unofficial software download sources are also used in a similar manner. Criminals present malicious executables as legitimate software, thereby tricking users into manually downloading and installing malware.

Threat Summary:
Name Jack virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .jack (this ransomware also appends filenames with victim's unique ID and developer's email address)
Ransom Demanding Message Pop-up window, RETURN FILES.txt text file
Cyber Criminal Contact lockhelp@qq.com
Detection Names Avast (Win32:Trojan-gen), ESET-NOD32 (Win32/Filecoder.Crysis.P), Kaspersky (Trojan-Ransom.Win32.Foreign.oghu), McAfee (Artemis!734F9B50616F), 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 Jack 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 careless behavior and lack of knowledge of these threats. The key to safety is caution. Therefore, pay close attention when browsing the Internet and downloading/installing/updating software. Handle all email attachments with care. If the received link/file is irrelevant or the sender seem suspicious/unrecognizable, do not open anything. Your software should be downloaded from official sources only (via direct download links) rather than using third party download/installation tools, since they are often used to proliferate malware. The same applies to software updates. You should update installed applications and operating systems only using tools provided by the official developer or, even better, implemented update functions. Be aware that software piracy is a cyber crime and, as already mentioned, the risk of infections is extremely high. Therefore, never attempt to crack installed applications. Have a reputable anti-virus/anti-spyware suite installed and running at all times. Software of this type can detect and eliminate malware before the system is harmed. If your computer is already infected with Jack, we recommend running a scan with Spyhunter for Windows to automatically eliminate this ransomware.

Text presented in Jack ransomware pop-up window:

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 Jack text file ("RETURN FILES.txt"):

Jack text file

Text presented within this file:

All your data is encrypted!
for return write to mail:

Screenshot of files encrypted by Jack (".jack" extension):

Files encrypted by Jack

Jack ransomware removal:

Instant automatic removal of Jack 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 Jack 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 Jack 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 Jack 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 Jack 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 Jack 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 Jack, 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 Jack 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 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 Jack 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 virus and spyware activity level today:

Medium threat activity

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

QR Code
Jack 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 Jack virus on your mobile device.
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Platform: Windows

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