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Mr. Dec Virus — How To Remove it and Restore Affected Data

Mr. Dec virus image

The Mr. Dec virus has been discovered in a small attack campaign. While the initial strains do not feature advanced code it is expected that future versions will be much more dangerous. The affected files are renamed with random extensions, read more about the threat in our removal guide.

SIDENOTE: This post was originally published in May 2018. But we gave it an update in August 2019.

Threat Summary

Name Mr. Dec
Type Ransomware, Cryptovirus
Short Description The ransomware encrypts sensitive information on your computer system with the .[random-extension] extensions and demands a ransom to be paid to allegedly recover them.
Symptoms The ransomware will encrypt your files with a strong encryption algorithm.
Distribution Method Spam Emails, Email Attachments
Detection Tool See If Your System Has Been Affected by malware


Malware Removal Tool

User Experience Join Our Forum to Discuss Mr. Dec.
Data Recovery Tool Windows Data Recovery by Stellar Phoenix Notice! This product scans your drive sectors to recover lost files and it may not recover 100% of the encrypted files, but only few of them, depending on the situation and whether or not you have reformatted your drive.

Mr. Dec Virus — Update August 2019

A recent attack wave using the Mr. Dec ransomware has been detected. However instead of the nae attributed to the ransomware the majority of user complaints are for “you are unlucky the terrible virus”. It is very possible that the original hackers or another criminal group have taken on the threat and created a new version taking on this name.

Given the fact that in this month this version has been used in an attack campaign we assume that possibly new functionality or changes to the behavior pattern have been made. The ransomware note or lockscreen may read warning messages that are designed in a different way than before, possibly with the message you are unlucky the terrible virus has captured your files.

Mr. Dec Virus – Distribution Ways

The Mr. Dec virus has been identified in a very small attack campaign that does not give out the primary distribution tactics. As such we expect that the most common methods are going to be used.

Future Mr. Dec virus campaigns can utilize SPAM email messages that rely on social engineering tactics. They use text and graphics that have been hijacked from legitimate sites, products and services in order to blackmail the recipients into infecting themselves. This is done by either attaching the file directly to the messages or hyperlinking the relevant in the body contents. In connection with this payloads can be spread using them. Two of the most popular examples include the following:

  • Software Installers — The criminals behind the threat can embed the relevant virus code in application installers. Usually the most popular ones are used: creativity suites, system utilities, productivity apps, office programs and even computer games.
  • Infected Documents — Using similar mechanisms the hackers may embed scripts that lead to the Mr. Dec infection. Practically all document types can be affected: text files, presentations, databases or spreadsheets. Once they are opened by the victims a notification message will appear asking the users to enable the built-in macros. If they do this then the infection will begin.

Another possibility would be the use of browser hijackers. They represent malicious web browser plugins that are made for the most popular applications: Mozilla Firefox, Google Chrome, Internet Explorer, Opera, Safari and Microsoft Edge. Their main goal is to redirect the victims to a hacker-controlled site by changing the browser’s default settings — home page, search engine and new tabs page. Afterwards the Mr. Dec virus infection follows. These strains are usually found on the relevant web browser plugin repositories. The hackers typically make use of fake developer credentials and user reviews along with an elaborate description with the promise of adding new useful features or otherwise changing the browsing experience.

Other delivery methods include the use of web scripts that come in various forms and can even affect legitiamte and well-known sites through compromised ad and affiliate networks. The most common forms are all manners of pop-ups, redirects, in-body hyperlinks and other scripts.

Mr. Dec Virus – In-Depth Analysis

The Mr. Dec virus appears to be a newly created ransomare that does not originate from any of the well-known malware families. This means that either the threat has been created by by its operators or it has been bought from the underground markets. Whatever its origins it appears that the captured samples are test versions or the initial builds. This means that many of the essential virus features are not yet integrated. If the first attacks are successful then future versions will likely be developed.

The initial infection can begin with an information gathering engine. It is programmed to harvest various types of strings in advance. The harvested campaign metrics can be used to optimize the attacks by registering the installed hardware components and certain operating system strings. The same engine can be used to harvest personally-identifiable about the victims that can expose their identity. Example strings include their name, address, telephone number, geographic location, interests, passwords and account credentials.

The information can be processed by the stealth protection module which protects the malicious executable from any applications or services that can interfere with its correct execution. Examples include anti-virus products, sandbox environments and virtual machine hosts.

The Mr. Dec virus can be programmed into modifying the Windows Registry entries related either to the user-installed applications or the operating system itself. When the virus modifies application entries certain services or functions can be rendered non-working. Windows-related entries can lead to overall performance issues.

This is also used to set the Mr. Dec virus as a persistent threat. This means that the virus will start automatically once the computer boots and access to certain menu options will be blocked. This includes the recovery boot menu. In such cases the only way to recover the infected machines is by using a quality anti-spyware solution, read our removal instructions for further information. To make recovery more difficult the threat can also be configured to delete the Shadow Volume Copies of the affected data. This means that data recovery is possible with the use of a professional application.

Advanced versions of the Mr. Dec virus can also be used with a malware network connection to the hacker-controlled servers. It is used in order to harvest the acquired personal data, as well as spy upon the victims in real time. Such methods are widely used in a Trojan-like manner that allow the controllers to overtake control of the machines. They are also among that main methods that are used to deploy additional threats.

We remind our readers that many of the updated ransomware threats at some point add browser hijacker like code that can interact with web browsers and other user-installed applications. This includes the likes of tracking cookies, plugins and other malicious software without the victim’s consent and knowledge.

Mr. Dec Virus – Encryption Process

The associated ransomware engine with the Mr. Dec virus is fully functional even with the test versions that were captured by the analysts. Like other popular ransomware threats it uses a strong cipher (AES) that is used to encrypt sensitive user data. It uses a built-in list that affects the following data:

  • Archives
  • Backups
  • Documents
  • Databases
  • Images
  • Videos
  • Music

Instead of using a generic rename template the Mr. Dec virus processes the affected data with a random extension which follows the following formula: .[ID][ID]. This means that a randomly-generated string will be made for each victim, it is very likely that it is calculated using the harvested hardware components information.

A ransomware note is crafted in a file called Decoding help.hta that contains the following message:

You are unlucky! The terrible virus has captured your files! For decoding please contact by email mr.dec@protonmail.com or mr.dec@tutanota.com
ID ***** ID
1. In the subject line, write your ID.
2. Attach 1-2 infected files that do not contain important information (less than 2 mb)
3. Attach the file with the location c:\Windows\DECODE KEY.KEY
are required to generate the decoder and restore the test file.
Hurry up! Time is limited!
At the end of this time, the private key for generating the decoder will be destroyed. Files will not be restored!

Remove Mr. Dec Virus and Restore .[random-extension] Files

If your computer system got infected with the Mr. Dec ransomware virus, you should have a bit of experience in removing malware. You should get rid of this ransomware as quickly as possible before it can have the chance to spread further and infect other computers. You should remove the ransomware and follow the step-by-step instructions guide provided below.

Martin Beltov

Martin graduated with a degree in Publishing from Sofia University. As a cyber security enthusiast he enjoys writing about the latest threats and mechanisms of intrusion.

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Attention! SensorsTechForum strongly recommends that all malware victims should look for assistance only by reputable sources. Many guides out there claim to offer free recovery and decryption for files encrypted by ransomware viruses. Be advised that some of them may only be after your money.

As a site that has been dedicated to providing free removal instructions for ransomware and malware since 2014, SensorsTechForum’s recommendation is to only pay attention to trustworthy sources.

How to recognize trustworthy sources:

  • Always check "About Us" web page.
  • Profile of the content creator.
  • Make sure that real people are behind the site and not fake names and profiles.
  • Verify Facebook, LinkedIn and Twitter personal profiles.


with Anti-Malware
We recommend you to download SpyHunter and run free scan to remove all virus files on your PC. This saves you hours of time and effort compared to doing the removal yourself.
SpyHunter 5 free remover allows you, subject to a 48-hour waiting period, one remediation and removal for results found. Read EULA and Privacy Policy

Windows Mac OS X

How to Remove Mr. Dec from Windows.

Step 1: Boot Your PC In Safe Mode to isolate and remove Mr. Dec


Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your PC with SpyHunter

Keep in mind, that SpyHunter’s scanner is only for malware detection. If SpyHunter detects malware on your PC, you will need to purchase SpyHunter's malware removal tool to remove the malware threats. Read our SpyHunter 5 review. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria

1. Hold Windows key() + R

2. The "Run" Window will appear. In it, type "msconfig" and click OK.

3. Go to the "Boot" tab. There select "Safe Boot" and then click "Apply" and "OK".
Tip: Make sure to reverse those changes by unticking Safe Boot after that, because your system will always boot in Safe Boot from now on.

4. When prompted, click on "Restart" to go into Safe Mode.

5. You can recognise Safe Mode by the words written on the corners of your screen.

Step 2: Uninstall Mr. Dec and related software from Windows

Here is a method in few easy steps that should be able to uninstall most programs. No matter if you are using Windows 10, 8, 7, Vista or XP, those steps will get the job done. Dragging the program or its folder to the recycle bin can be a very bad decision. If you do that, bits and pieces of the program are left behind, and that can lead to unstable work of your PC, errors with the file type associations and other unpleasant activities. The proper way to get a program off your computer is to Uninstall it. To do that:

1. Hold the Windows Logo Button and "R" on your keyboard. A Pop-up window will appear.

2. In the field type in "appwiz.cpl" and press ENTER.

3. This will open a window with all the programs installed on the PC. Select the program that you want to remove, and press "Uninstall"
Follow the instructions above and you will successfully uninstall most programs.

Step 3: Clean any registries, created by Mr. Dec on your computer.

The usually targeted registries of Windows machines are the following:

  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce

You can access them by opening the Windows registry editor and deleting any values, created by Mr. Dec there. This can happen by following the steps underneath:

1. Open the Run Window again, type "regedit" and click OK.

2. When you open it, you can freely navigate to the Run and RunOnce keys, whose locations are shown above.

3. You can remove the value of the virus by right-clicking on it and removing it.
Tip: To find a virus-created value, you can right-click on it and click "Modify" to see which file it is set to run. If this is the virus file location, remove the value.

Before starting "Step 4", please boot back into Normal mode, in case you are currently in Safe Mode.
This will enable you to install and use SpyHunter 5 successfully.

Step 4: Scan for Mr. Dec with SpyHunter Anti-Malware Tool

1. Click on the "Download" button to proceed to SpyHunter's download page.

It is recommended to run a scan before purchasing the full version of the software to make sure that the current version of the malware can be detected by SpyHunter. Click on the corresponding links to check SpyHunter's EULA, Privacy Policy and Threat Assessment Criteria.

2. After you have installed SpyHunter, wait for it to update automatically.


3. After the update process has finished, click on the 'Malware/PC Scan' tab. A new window will appear. Click on 'Start Scan'.


4. After SpyHunter has finished scanning your PC for any files of the associated threat and found them, you can try to get them removed automatically and permanently by clicking on the 'Next' button.


If any threats have been removed, it is highly recommended to restart your PC.

Step 5 (Optional): Try to Restore Files Encrypted by Mr. Dec.

Ransomware infections and Mr. Dec aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.

1. Download the reccomended Data Recovery software by clicking on the link underneath:

Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.

Windows Mac OS X

Get rid of Mr. Dec from Mac OS X.

Step 1: Uninstall Mr. Dec and remove related files and objects

Manual Removal Usually Takes Time and You Risk Damaging Your Files If Not Careful!
We Recommend To Scan Your Mac with SpyHunter for Mac
Keep in mind, that SpyHunter for Mac needs to purchased to remove the malware threats. Click on the corresponding links to check SpyHunter’s EULA and Privacy Policy

1. Hit the ⇧+⌘+U keys to open Utilities. Another way is to click on “Go” and then click “Utilities”, like the image below shows:

2. Find Activity Monitor and double-click it:

3. In the Activity Monitor look for any suspicious processes, belonging or related to Mr. Dec:

Tip: To quit a process completely, choose the “Force Quit” option.

4. Click on the "Go" button again, but this time select Applications. Another way is with the ⇧+⌘+A buttons.

5. In the Applications menu, look for any suspicious app or an app with a name, similar or identical to Mr. Dec. If you find it, right-click on the app and select “Move to Trash”.

6: Select Accounts, after which click on the Login Items preference. Your Mac will then show you a list of items that start automatically when you log in. Look for any suspicious apps identical or similar to Mr. Dec. Check the app you want to stop from running automatically and then select on the Minus (“-“) icon to hide it.

7: Remove any left-over files that might be related to this threat manually by following the sub-steps below:

  • Go to Finder.
  • In the search bar type the name of the app that you want to remove.
  • Above the search bar change the two drop down menus to “System Files” and “Are Included” so that you can see all of the files associated with the application you want to remove. Bear in mind that some of the files may not be related to the app so be very careful which files you delete.
  • If all of the files are related, hold the ⌘+A buttons to select them and then drive them to “Trash”.

In case you cannot remove Mr. Dec via Step 1 above:

In case you cannot find the virus files and objects in your Applications or other places we have shown above, you can manually look for them in the Libraries of your Mac. But before doing this, please read the disclaimer below:

Disclaimer! If you are about to tamper with Library files on Mac, be sure to know the name of the virus file, because if you delete the wrong file, it may cause irreversible damage to your MacOS. Continue on your own responsibility!

1: Click on "Go" and Then "Go to Folder" as shown underneath:

2: Type in "/Library/LauchAgents/" and click Ok:

3: Delete all of the virus files that have similar or the same name as Mr. Dec. If you believe there is no such file, do not delete anything.

You can repeat the same procedure with the following other Library directories:

→ ~/Library/LaunchAgents

Tip: ~ is there on purpose, because it leads to more LaunchAgents.

Click the button below below to download SpyHunter for Mac and scan for Mr. Dec:


SpyHunter for Mac

Step 3 (Optional): Try to Restore Files Encrypted by Mr. Dec.

Ransomware infections and Mr. Dec aim to encrypt your files using an encryption algorithm which may be very difficult to decrypt. This is why we have suggested a data recovery method that may help you go around direct decryption and try to restore your files. Bear in mind that this method may not be 100% effective but may also help you a little or a lot in different situations.

1. Download the reccomended Data Recovery software by clicking on the link underneath:

Simply click on the link and on the website menus on top, choose Data Recovery - Data Recovery Wizard for Windows or Mac (depending on your OS), and then download and run the tool.

Mr. Dec FAQ

What is Mr. Dec ransomware and how does it work?

Mr. Dec is a ransomware infection - the malicious software that enters your computer silently and blocks either access to the computer itself or encrypt your files.

Many ransomware viruses use sophisticated encryption algorithm how to make your files inaccessible. The goal of ransomware infections is to demand that you pay a ransom payment to get access to your files back.

How does Mr. Dec ransomware infect my computer?

Via several ways.Mr. Dec Ransomware infects computers by being sent via phishing e-mails, containing virus attachment.

This attachment is usually masked as an important document, like an invoice, bank document or even a plane ticket and it looks very convincing to users.

After you download and execute this attachment, a drive-by download occurs and your computer is infected with the ransomware virus.

Another way, you may become a victim of Mr. Dec is if you download a fake installer, crack or patch from a low reputation website or if you click on a virus link. Many users report getting a ransomware infection by downloading torrents.

How to open .Mr. Dec files?

You can't. At this point the .Mr. Dec files are encrypted. You can only open them once they are decrypted.

Decryptor did not decrypt my data. What now?

Do not panic and backup the files. If a decryptor did not decrypt your .Mr. Dec files successfully, then do not despair, because this virus is still new.

One way to restore files, encrypted by Mr. Dec ransomware is to use a decryptor for it. But since it's a new virus, advised that the decryption keys for it may not be out yet and available to the public. We will update this article and keep you posted as soon as this decryptor is released.

How Do I restore ".Mr. Dec" files (Other Methods)?

Yes, sometimes files can be restored. We have suggested several file recovery methods that could work if you want to restore .Mr. Dec files.

These methods are in no way 100% guarantee that you will be able to get your files back. But if you have a backup, your chances of success are much greater.

How do I get rid of Mr. Dec ransomware virus?

The safest way and the most efficient one for the removal of this ransomware infection is the use a professional anti malware software. It will scan for and locate Mr. Dec ransomware and then remove it without causing any additional harm to your important .Mr. Dec files.

Also, keep in mind that viruses like Mr. Dec ransomware also install Trojans and keyloggers that can steal your passwords and accounts. Scanning your computer with an anti-malware software will make sure that all of these virus components are removed and your computer is protected in the future.

What to Do If nothing works?

There is still a lot you can do. If none of the above methods seem to work for you, then try these methods:

  • Try to find a safe computer from where you can can login on your own line accounts like One Drive, iDrive, Google Drive and so on.
  • Try to contact your friends, relatives and other people so that they can check if they have some of your important photos or documents just in case you sent them.
  • Also, check if some of the files that were encrypted it can be re-downloaded from the web.
  • Another clever way to get back some of your files is to find another old computer, a flash drive or even a CD or a DVD where you may have saved your older documents. You might be surprised what will turn up.
  • You can also go to your email account to check if you can send any attachments to other people. Usually what is sent the email is saved on your account and you can re-download it. But most importantly, make sure that this is done from a safe computer and make sure to remove the virus first.

More tips you can find on our forums, where you can also asks any questions about your ransomware problem.

How to Report Ransomware to Authorities?

In case your computer got infected with a ransomware infection, you can report it to the local Police departments. It can help authorities worldwide track and determine the perpetrators behind the virus that has infected your computer. Below, we have prepared a list with government websites, where you can file a report in case you are a victim of a cybercrime:

Cyber-security authorities, responsible for handling ransomware attack reports in different regions all over the world:

Reports may be responded to in different timeframes, depending on your local authorities.

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