How to uninstall Jester ransomware?

Also Known As: Jester ransomware virus
Damage level: Severe

What is Jester ransomware?

Ransomware is a type of malware that prevents victims from accessing their files. It encrypts files and generates a ransom note (or multiple ransom notes) to provide contact and (or) payment information. Usually, ransomware renames encrypted files as well (it changes their extension by appending its own).

Jester generates two ransom notes: a pop-up window and an HTML file ("jester.html"). Also, it displays another pop-up window with a countdown timer in it. After the timer reaches zero, a message saying that ransomware is deleting files appears in that pop-up window. It is noteworthy that Jester ransomware does not rename encrypted files (it does not change their extensions).

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

Jester decrypt instructions (pop-up window)

Jester ransom note overview

As mentioned in the introduction, Jasper ransomware generates two ransom notes - it displays a pop-up window and an HTML file. As stated in these ransom notes, all files are encrypted. To get a decryption key, victims have to pay 5.9 million dollars. If victims do not pay a ransom, they will lose all their files and access to the entire operating system.

Also, victims are warned not to shut down the infected computer or try to remove ransomware because they will lose 1000 files the next time they turn on their computers. In conclusion, victims are instructed to pay a little less than 6 million dollars in a short time and warned that refusing to pay a ransom will result in the loss of all files and access to the operating system.

More information about ransomware

Typically, cybercriminals behind ransomware attacks are the only ones who can decrypt files/provide decryption tools. Sometimes, it is possible to decrypt files with a tool downloaded from the Internet. However, free data decryption is rarely a possible option. Unfortunately, no third-party (free) tool can decrypt files encrypted by the Jester ransomware.

The only way to recover files for free is to restore them from a backup that has been created before a ransomware attack. When victims do not have a data backup, they have two options: lose files or purchase a decryption tool. It is strongly recommended not to choose the second option - it is likely that cybercriminals will not send a decryption tool.

One more important thing is to uninstall ransomware from the infected computer as soon as possible - by removing ransomware, victims can prevent further damage. More precisely, installed ransomware may encrypt more files (perform new encryptions) or infect computers on the local network. A step-by-step malware removal guide is provided below.

Similarities with other ransomware variants

Most ransomware variants are designed to encrypt files and keep them inaccessible until a ransom is paid. Victims are provided with contact, payment, and other information. The main differences between ransomware attacks are the prices of decryption tools, and cryptographic algorithms (symmetric or asymmetric) uses to make files inaccessible.

Ransomware victims cannot decrypt for free unless there is a free decryption tool on the Internet. Victims can recover files without losing money only if they have a data backup. Therefore, it is recommended to create backups regularly and keep them stored on some remote server or unplugged storage device. More ransomware examples are VietnamPav, Karma Group, and Karen.

How did ransomware infect my computer?

Pretty often, users install ransomware on their computers by opening malicious attachments or links in emails received from cybercriminals. Typically, emails are used to deliver malware through malicious Microsoft Office, PDF documents, archive files like RAR, ZIP, executable files (like EXE), JavaScript files.

Another way to distribute malicious software is to trick users into installing a certain Trojan - a Trojan that is designed to install additional malware (install its payload). Typically, Trojans are disguised as legitimate programs. Cybercriminals distribute using the methods described in this section.

Another way to distribute malware is to trick users into downloading malicious files from unreliable sources, such as unofficial websites, download pages for freeware, free file hosting sites, Peer-to-Peer networks (torrent clients, eMule, and other networks), third-party downloaders, etc. Users infect computers by opening files downloaded via unreliable sources.

Furthermore, malware can be distributed through cracking tools (illegal tools designed to activate legitimate software for free). It is very common for these tools to be bundled with malware. Cybercriminals achieve their goal when users try to bypass software activation without spending money on it.

One more popular way to distribute malware is to trick users into downloading and using fake software updaters. Fake updaters exploit vulnerabilities in operating systems or software or infect computers by installing malware instead of updates and fixes. They usually look like legitimate tools (for example, like a fake Adobe Flash Player installer).

Threat Summary:
Name Jester ransomware virus
Threat Type Ransomware, Crypto Virus, Files locker
Ransom Demanding Message Pop-up window, jester.html
Ransom Amount $5.9
Detection Names Avast (Win32:MalwareX-gen [Trj]), Combo Cleaner (Trojan.GenericKD.37377741), ESET-NOD32 (A Variant Of MSIL/Filecoder.AHF), Kaspersky (HEUR:Trojan.MSIL.Shelpak.gen), Microsoft (Ransom:MSIL/CryptoLocker.DF!MTB), 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.
Additional Information Jester does not change file extensions or provide contact information.
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)

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How to protect yourself from ransomware infections?

Files and applications should be downloaded from official pages (and via direct download links). Peer-to-Peer networks, unofficial sites, third-party downloaders, installers and other sources, tools should not be used neither to download or install any files or programs. The aforementioned sources, tools can be used to distribute malware.

Installed programs have to be updated and activated with tools or functions provided by their developers. More often than not, third-party updaters or activation tools (cracking) tools are malicious. Moreover,  it is not legal to use cracking tools to bypass software activation, or use installers for cracked software.

Emails that contain website links or attachments should be examined before opening their contents. It is important to keep in mind that cybercriminals can use email as a tool to deliver malware via malicious links or attachments. Typically, their emails look like letters from legitimate companies (for example, they have real logos in them).

A computer should be scanned for threats regularly. It is recommended to scan it with a reputable antivirus or anti-spyware software. If your computer is already infected with Jester, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

Text presented in the Jester's main pop-up window:

Your files are encrypted.

To get the key to decrypt files, you have to pay $ 5.9 million.  
f the payment is not made tomorrow night, we will lock the entire system.
More instructions coming soon. - jester.


There's an unequal amount of good and bad in most things. The trick is to figure out the ratio and act accordingly.

Screenshot of Jester's "jester.html" file:

jester ransomware jester.html file

Text in this file (Spanish and English versions):

Original (Spanish):

Quiero jugar un juego contigo. Dejame explicarte las reglas: Tus archivos personales se borraran. Tus fotos, videos, documentos, etc.¡Pero no te preocupes Solo sucederá si no cumple.Sin embargo, ya cifre sus archivos personales, por lo que no puede acceder a ellos alterminar el timpo eliminare todos tus archivos de forma permanente, por lo que tampoco podré acceder a ellos.Si apaga la computadora o intenta cerrarme, la proxima vez que comiencese eliminarán 1000 archivos como castigo. Si, querrá que comience la proxima vez, ya que soy el unico uno que sea capaz de descifrar sus datos personales por usted¡Ahora, comencemos y disfrutemos nuestro pequeño juego juntos!

Rough English translation:

I want to play a game with you. Let me explain the rules: Your personal files will be deleted. Your photos, videos, documents, etc. But do not worry It will only happen if you do not comply. However, you already encrypt your personal files, so you can not access them at the end of the time I will delete all your files permanently, so I won't be able to access them either. If you turn off the computer or try to shut me down, the next time I start it will delete 1000 files as punishment. Yes, you will want me to start next time, as I am the only one who is able to decrypt your personal data for you. Now let's get started and enjoy our little game together!

Screenshot of a pop-up window that appears when the timer reaches 0:

jester ransomware pop-up displayed once the timer reaches 0

Screenshot of files encrypted by Jester:

Files encrypted by Jester ransomware

Jester ransomware removal:

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Video suggesting what steps should be taken in case of a ransomware infection:

Quick menu:

Reporting ransomware to authorities:

If you are a victim of a ransomware attack we recommend reporting this incident to authorities. By providing information to law enforcement agencies you will help track cybercrime and potentially assist in the prosecution of the attackers. Here's a list of authorities where you should report a ransomware attack. For the complete list of local cybersecurity centers and information on why you should report ransomware attacks, read this article.

List of local authorities where ransomware attacks should be reported (choose one depending on your residence address):

Isolating the infected device:

Some ransomware-type infections are designed to encrypt files within external storage devices, infect them, and even spread throughout the entire local network. For this reason, it is very important to isolate the infected device (computer) as soon as possible.

Step 1: Disconnect from the internet.

The easiest way to disconnect a computer from the internet is to unplug the Ethernet cable from the motherboard, however, some devices are connected via a wireless network and for some users (especially those who are not particularly tech-savvy), disconnecting cables may seem troublesome. Therefore, you can also disconnect the system manually via Control Panel:

Navigate to the "Control Panel", click the search bar in the upper-right corner of the screen, enter "Network and Sharing Center" and select search result: Disconnecting computer from the Internet (step 1)

Click the "Change adapter settings" option in the upper-left corner of the window: Disconnecting computer from the Internet (step 2)

Right-click on each connection point and select "Disable". Once disabled, the system will no longer be connected to the internet. To re-enable the connection points, simply right-click again and select "Enable". Disconnecting computer from the Internet (step 3)

Step 2: Unplug all storage devices.

As mentioned above, ransomware might encrypt data and infiltrate all storage devices that are connected to the computer. For this reason, all external storage devices (flash drives, portable hard drives, etc.) should be disconnected immediately, however, we strongly advise you to eject each device before disconnecting to prevent data corruption:

Navigate to "My Computer", right-click on each connected device, and select "Eject": Ejecting external storage devices

Step 3: Log-out of cloud storage accounts.

Some ransomware-type might be able to hijack software that handles data stored within "the Cloud". Therefore, the data could be corrupted/encrypted. For this reason, you should log-out of all cloud storage accounts within browsers and other related software. You should also consider temporarily uninstalling the cloud-management software until the infection is completely removed.

Identify the ransomware infection:

To properly handle an infection, one must first identify it. Some ransomware infections use ransom-demand messages as an introduction (see the WALDO ransomware text file below).

Identify ransomware-type infection (step 1)

This, however, is rare. In most cases, ransomware infections deliver more direct messages simply stating that data is encrypted and that victims must pay some sort of ransom. Note that ransomware-type infections typically generate messages with different file names (for example, "_readme.txt", "READ-ME.txt", "DECRYPTION_INSTRUCTIONS.txt", "DECRYPT_FILES.html", etc.). Therefore, using the name of a ransom message may seem like a good way to identify the infection. The problem is that most of these names are generic and some infections use the same names, even though the delivered messages are different and the infections themselves are unrelated. Therefore, using the message filename alone can be ineffective and even lead to permanent data loss (for example, by attempting to decrypt data using tools designed for different ransomware infections, users are likely to end up permanently damaging files and decryption will no longer be possible even with the correct tool).

Another way to identify a ransomware infection is to check the file extension, which is appended to each encrypted file. Ransomware infections are often named by the extensions they append (see files encrypted by Qewe ransomware below).

Identify ransomware-type infection (step 2)

This method is only effective, however, when the appended extension is unique - many ransomware infections append a generic extension (for example, ".encrypted", ".enc", ".crypted", ".locked", etc.). In these cases, identifying ransomware by its appended extension becomes impossible.

One of the easiest and quickest ways to identify a ransomware infection is to use the ID Ransomware website. This service supports most existing ransomware infections. Victims simply upload a ransom message and/or one encrypted file (we advise you to upload both if possible).

Identify ransomware-type infection (step 3)

The ransomware will be identified within seconds and you will be provided with various details, such as the name of the malware family to which the infection belongs, whether it is decryptable, and so on.

Example 1 (Qewe [Stop/Djvu] ransomware):

Identify ransomware-type infection (step 4)

Example 2 (.iso [Phobos] ransomware):

Identify ransomware-type infection (step 5)

If your data happens to be encrypted by ransomware that is not supported by ID Ransomware, you can always try searching the internet by using certain keywords (for example, a ransom message title, file extension, provided contact emails, crypto wallet addresses, etc.).

Search for ransomware decryption tools:

Encryption algorithms used by most ransomware-type infections are extremely sophisticated and, if the encryption is performed properly, only the developer is capable of restoring data. This is because decryption requires a specific key, which is generated during the encryption. Restoring data without the key is impossible. In most cases, cybercriminals store keys on a remote server, rather than using the infected machine as a host. Dharma (CrySis), Phobos, and other families of high-end ransomware infections are virtually flawless, and thus restoring data encrypted without the developers' involvement is simply impossible. Despite this, there are dozens of ransomware-type infections that are poorly developed and contain a number of flaws (for example, the use of identical encryption/decryption keys for each victim, keys stored locally, etc.). Therefore, always check for available decryption tools for any ransomware that infiltrates your computer.

Finding the correct decryption tool on the internet can be very frustrating. For this reason, we recommend that you use the No More Ransom Project and this is where identifying the ransomware infection is useful. The No More Ransom Project website contains a "Decryption Tools" section with a search bar. Enter the name of the identified ransomware, and all available decryptors (if there are any) will be listed.

Searching for ransomware decryption tools in nomoreransom.org website

Restore files with data recovery tools:

Depending on the situation (quality of ransomware infection, type of encryption algorithm used, etc.), restoring data with certain third-party tools might be possible. Therefore, we advise you to use the Recuva tool developed by CCleaner. This tool supports over a thousand data types (graphics, video, audio, documents, etc.) and it is very intuitive (little knowledge is necessary to recover data). In addition, the recovery feature is completely free.

Step 1: Perform a scan.

Run the Recuva application and follow the wizard. You will be prompted with several windows allowing you to choose what file types to look for, which locations should be scanned, etc. All you need to do is select the options you're looking for and start the scan. We advise you to enable the "Deep Scan" before starting, otherwise, the application's scanning capabilities will be restricted.

Recuva data recovery tool wizard

Wait for Recuva to complete the scan. The scanning duration depends on the volume of files (both in quantity and size) that you are scanning (for example, several hundred gigabytes could take over an hour to scan). Therefore, be patient during the scanning process. We also advise against modifying or deleting existing files, since this might interfere with the scan. If you add additional data (for example, downloading files/content) while scanning, this will prolong the process:

Recuva data recovery tool scan time

Step 2: Recover data.

Once the process is complete, select the folders/files you wish to restore and simply click "Recover". Note that some free space on your storage drive is necessary to restore data:

Recuva data recovery tool recovering data

Create data backups:

Proper file management and creating backups is essential for data security. Therefore, always be very careful and think ahead.

Partition management: We recommend that you store your data in multiple partitions and avoid storing important files within the partition that contains the entire operating system. If you fall into a situation whereby you cannot boot the system and are forced to format the disk on which the operating system is installed (in most cases, this is where malware infections hide), you will lose all data stored within that drive. This is the advantage of having multiple partitions: if you have the entire storage device assigned to a single partition, you will be forced to delete everything, however, creating multiple partitions and allocating the data properly allows you to prevent such problems. You can easily format a single partition without affecting the others - therefore, one will be cleaned and the others will remain untouched, and your data will be saved. Managing partitions is quite simple and you can find all the necessary information on Microsoft's documentation web page.

Data backups: One of the most reliable backup methods is to use an external storage device and keep it unplugged. Copy your data to an external hard drive, flash (thumb) drive, SSD, HDD, or any other storage device, unplug it and store it in a dry place away from the sun and extreme temperatures. This method is, however, quite inefficient, since data backups and updates need to be made regularly. You can also use a cloud service or remote server. Here, an internet connection is required and there is always the chance of a security breach, although it's a really rare occasion.

We recommend using Microsoft OneDrive for backing up your files. OneDrive lets you store your personal files and data in the cloud, sync files across computers and mobile devices, allowing you to access and edit your files from all of your Windows devices. OneDrive lets you save, share and preview files, access download history, move, delete, and rename files, as well as create new folders, and much more.

You can back up your most important folders and files on your PC (your Desktop, Documents, and Pictures folders). Some of OneDrive’s more notable features include file versioning, which keeps older versions of files for up to 30 days. OneDrive features a recycling bin in which all of your deleted files are stored for a limited time. Deleted files are not counted as part of the user’s allocation.

The service is built using HTML5 technologies and allows you to upload files up to 300 MB via drag and drop into the web browser or up to 10 GB via the OneDrive desktop application. With OneDrive, you can download entire folders as a single ZIP file with up to 10,000 files, although it can’t exceed 15 GB per single download.

OneDrive comes with 5 GB of free storage out of the box, with an additional 100 GB, 1 TB, and 6 TB storage options available for a subscription-based fee. You can get one of these storage plans by either purchasing additional storage separately or with Office 365 subscription.

Creating a data backup:

The backup process is the same for all file types and folders. Here’s how you can back up your files using Microsoft OneDrive

Step 1: Choose the files/folders you want to backup.

Click the OneDrive icon in the taskbar

Click the OneDrive cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.

Select Help & Settings and click Settings

Click Help & Settings and then select Settings from the drop-down menu.

Select the Backup tab and click Manage backup

Go to the Backup tab and click Manage backup.

Select folders to backup and click Start backup

In this menu, you can choose to backup the Desktop and all of the files on it, and Documents and Pictures folders, again, with all of the files in them. Click Start backup.

Now, when you add a file or folder in the Desktop and Documents and Pictures folders, they will be automatically backed up on OneDrive.

To add folders and files, not in the locations shown above, you have to add them manually.

Select a file manually and copy it

Open File Explorer and navigate to the location of the folder/file you want to backup. Select the item, right-click it, and click Copy.

Paste the copied file in the OneDrive folder to create a backup

Then, navigate to OneDrive, right-click anywhere in the window and click Paste. Alternatively, you can just drag and drop a file into OneDrive. OneDrive will automatically create a backup of the folder/file.

File statuses in OneDrive folder

All of the files added to the OneDrive folder are backed up in the cloud automatically. The green circle with the checkmark in it indicates that the file is available both locally and on OneDrive and that the file version is the same on both. The blue cloud icon indicates that the file has not been synced and is available only on OneDrive. The sync icon indicates that the file is currently syncing.

Click Help & Settings and click View Online

To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.

Click the Settings cog and click Options

Step 2: Restore corrupted files.

OneDrive makes sure that the files stay in sync, so the version of the file on the computer is the same version on the cloud. However, if ransomware has encrypted your files, you can take advantage of OneDrive’s Version history feature that will allow you to restore the file versions prior to encryption.

Microsoft 365 has a ransomware detection feature that notifies you when your OneDrive files have been attacked and guide you through the process of restoring your files. It must be noted, however, that if you don’t have a paid Microsoft 365 subscription, you only get one detection and file recovery for free.

If your OneDrive files get deleted, corrupted, or infected by malware, you can restore your entire OneDrive to a previous state. Here’s how you can restore your entire OneDrive:


1. If you're signed in with a personal account, click the Settings cog at the top of the page. Then, click Options and select Restore your OneDrive.

If you're signed in with a work or school account,  click the Settings cog at the top of the page. Then, click Restore your OneDrive.

2. On the Restore your OneDrive page, select a date from the drop-down list. Note that if you're restoring your files after automatic ransomware detection, a restore date will be selected for you.

3. After configuring all of the file restoration options, click Restore to undo all the activities you selected.

The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups.

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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.

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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.

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