Mr. Dec ransomware: what it is and how to remove it

Mr. Dec ransomware is cryptovirus that was first spotted in mid-May 2018, and since then was updated multiple times.

Facts checked October 7, 2026. Removal steps tested on Windows 11 (26H2) and checked against Microsoft's and the browser makers' current documentation. Sections marked as our earlier report are the original text: they describe the threat as it was then and have not been reviewed since. The 2026 status, the removal steps and the questions are current.

Automatic

Get a free scan and check if your PC is infected.

Fortect finds malware, unwanted programs and the Windows damage they leave behind, and repairs it in one pass.

A free scan checks for the encryptor and anything installed with it; it does not decrypt files.

Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free.

Do it yourself · free Remove Mr. Dec ransomware yourself 6 steps, about 18 minutes, no software needed.

Start the steps
Mr. Dec: mr dec virus demands a ransom
Mr. Dec as our 2019 report showed it.

Mr. Dec ransomware: summary

DistributionSpam emails, exploits, web infects, brute-force attacks, fake updates, cracked software, etc.
NameMr. Dec
TypeRansomware
Danger levelVery high
Contact addressesmr.dec@tutanota.com, mr.dec@protonmail.com shine2@protonmail.com, shine1@tutanova.com JonStokton@Protonmail.com, JonStokton@tutanota.com filessnoop@aol.com, filessnoop@tutanota.com mr.file@protonmail.com localgroup@protonmail.com, localgroup@tutanota.com asist.help@protonmail.com, asist5000@tutanota.com
File extension.[ID]16 random characters[ID]
Removal

Scan the PC with security software to find and remove the malware and anything installed with it. Fortect scans Windows for malware and repairs the system files and settings it damaged.

Remove it nowTo use the full-featured product, you have to purchase a license for Fortect. The scan is free.
Show 13 more facts
Name of the ransom noteDecoding help.hta, Help for decrypting (mr.file@protonmail.com).txt, Decoder.hta
Related filesDECODE KEY.KEY, searchfiles.exe
Detection namesNo Microsoft detection name is known
Encrypted file extensionNot recorded in our earlier report
DecryptorNo free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates
Ransom notehelp.hta; additionally, the malware drops a ransom note Decoding help; the text is quoted in full below
DamageNot recorded in the old report
SymptomsA ransom note left in folders
Evidence6 write-ups by security sites; details still limited
Attacker contactsasist.help@protonmail.com
Free decryptorNo free decryptor is known (checked 7 October 2026)
First seen1 July 2019
Facts checked7 October 2026

What readers reported about Mr. Dec

files appended with oorr. prefix. Can't open .png, .txt, .doc, and .jpg file types. Hi guys! Could you please help me with this issue asap? I can't open photos, docs, videos and text files. The feature oorr. prefix. I hope that I haven't been caught by a ransomware...

A reader, 2015

Help recover files.txt ransomware. Need help!!!!!!!!!!! My PC was infected by Help recover files.txt ransomware. I think I opened spam that reported about taxes, but I'm not sure. Now I can't access personal files. Is there a way to restore data without paying that bitcoin?

A reader, 2015

From the comments under our earlier guide; names and contact details removed.

  • Note file: help.hta
  • Contact: asist.help@protonmail.com

From our report of Jul 2019 · not reviewed since

More from our earlier report on Mr. Dec

  • You can only delete Mr.
  • Dec ransomware with a professional anti-malware software

The Mr. Dec ransomware note

Text of help.hta

You are unlucky! The terrible virus has captured your files! For decoding please contact by email asist.help@protonmail.com or asist5000@tutanota.com

1. In the subject line, write your ID.

2. Attach 1-2 infected files that do not contain important information (less than 2 mb) are required to generate the decoder and restore the test file.

Attention!

Hurry up! Time is limited!

Do not contact third parties for help, this may lead to the fact that you will be deceived and you will not receive your decoder.

REMEMBER - only we have a tool to get your files back!

Mr. Dec: mr dec ransomware ransom note decoder hta
The message as our 2019 report captured it.

How to remove Mr. Dec ransomware

Tools you'll need

All of these are free except where noted. Download them on a clean device if the infected PC is offline.

  • A USB stick: to keep the ransom note, two or three encrypted files and screenshots off the infected PC.
  • Microsoft Defender Offline: built into Windows 11 and Windows 10; scans before Windows starts, so running malware cannot hide.
  • Microsoft Safety Scanner: a second, portable scanner with current signatures; each download works for 10 days.
  • ID Ransomware: identifies the family from the note and one encrypted file and says whether a decryptor exists.
  • No More Ransom: the free decryptors from police and security companies; check it again every few months.
  • Fortect (optional): scans Windows for malware and repairs the system files and settings it damaged. The free scan is in the box above.

How to remove Mr. Dec and get your files back

Work in this order.

Disconnecting comes first, removal comes before any restore, and nothing here asks you to contact the attackers.

  1. Step 1: Disconnect the PC and unplug backup drives

    Unplug the network cable or turn off Wi-Fi, and disconnect USB drives, external disks and network shares, so Mr. Dec cannot reach more files. Pause OneDrive, Google Drive or Dropbox sync, because synced folders upload the encrypted copies over the good ones.

    Leave the PC on but offline while you read the next steps, since a restart can let the ransomware run again. This applies to Windows 11 and Windows 10 alike.

    Windows 11 quick settings with Wi-Fi turned off
    Windows 11: turn off Wi-Fi to take the PC offline.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  2. Step 2: Save the ransom note and identify the family

    The name of the family decides whether a free decryptor can help. Copy the ransom note and two small encrypted files to a USB stick, and check them on another device with ID Ransomware or Crypto Sheriff.

    Note the extension added to the files, the contact address and the victim ID shown in the note. Keep the originals on the Windows 11 or Windows 10 PC untouched.

    A ransom note text file next to encrypted files in File Explorer
    Windows 11: the ransom note and encrypted files to copy for identification.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  3. Step 3: Check for a free decryptor

    Our last check found that for Mr. Dec, no free decryptor is known (checked 7 October 2026). Look again yourself in the No More Ransom list and the free decryptor pages of Emsisoft, Avast and Kaspersky, which add new families every year.

    A decryptor needs the ransomware gone first, or it encrypts the files again. Keep at least one copy of the encrypted files on an external drive, even if no tool works yet.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  4. Step 4: Remove the ransomware before you restore or decrypt

    Removing Mr. Dec does not bring the files back, but it has to come first. Start with Defender's Full scan, then the offline scan from the same Scan options page, which checks the disk before Windows loads.

    If the scan cannot start, use Safe Mode with Networking. Delete the ransom notes only after you have saved a copy, because removal tools sometimes leave them behind on Windows 11 and Windows 10.

    Windows Security Scan options with Microsoft Defender Antivirus offline scan selected
    Windows 11: Windows Security > Virus & threat protection > Scan options.

    Full procedure with screenshots: Run a Microsoft Defender Offline scan

  5. Step 5: Look for shadow copies of the files

    Windows keeps shadow copies for restore points and backups, and some ransomware fails to delete them. vssadmin list shadows in an administrator Command Prompt tells you at once whether any exist.

    If they do, right-click the folder that held your files, open Properties > Previous Versions, select a version from before the attack, and click Open to check it before you Restore or copy the files out. Windows 11 and Windows 10 both have the tab.

    Command Prompt running vssadmin list shadows
    Windows 11: vssadmin list shadows shows whether shadow copies exist.

    Full procedure with screenshots: Ransomware: first steps, finding a decryptor and recovering files

  6. Step 6: Restore the files from a backup or recover deleted originals

    A backup made before the attack is the surest way back. Connect it only once the PC is clean, then restore from File History, Windows Backup, OneDrive's Restore your OneDrive or your own external copies.

    Without a backup, try file recovery: the originals that Mr. Dec deleted may still be on the disk until something overwrites them. Install nothing new on the drive you want to recover from on the Windows 11 or Windows 10 PC.

    Full procedure with screenshots: Recover deleted files (Recycle Bin, backups, OneDrive) On uGetFix

Instructions for each browser and system

The detailed steps for every browser and system this guide covers. Open the one you use.

Manual removal using Safe Mode

Important! →
Manual removal guide might be too complicated for regular computer users. It requires advanced IT knowledge to be performed correctly (if vital system files are removed or damaged, it might result in full Windows compromise), and it also might take hours to complete. Therefore, we highly advise using the automatic method provided above instead.

Step 1. Access Safe Mode with Networking

Manual malware removal should be best performed in the Safe Mode environment.

Windows 7 / Vista / XP

  1. Click Start > Shutdown > Restart > OK.
  2. When your computer becomes active, start pressing F8 button (if that does not work, try F2, F12, Del, etc. - it all depends on your motherboard model) multiple times until you see the Advanced Boot Options window.
  3. Select Safe Mode with Networking from the list.Windows 7/XP

Windows 10 / Windows 8

  1. Right-click on Start button and select Settings.
    Settings
  2. Scroll down to pick Update & Security.
    Update and security
  3. On the left side of the window, pick Recovery.
  4. Now scroll down to find Advanced Startup section.
  5. Click Restart now.
    Reboot
  6. Select Troubleshoot.Choose an option
  7. Go to Advanced options.Advanced options
  8. Select Startup Settings.Startup settings
  9. Press Restart.
  10. Now press 5 or click 5) Enable Safe Mode with Networking.Enable safe mode

Step 2. Shut down suspicious processes

Windows Task Manager is a useful tool that shows all the processes running in the background. If malware is running a process, you need to shut it down:

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Click on More details.
    Open task manager
  3. Scroll down to Background processes section, and look for anything suspicious.
  4. Right-click and select Open file location.
    Open file location
  5. Go back to the process, right-click and pick End Task.
    End task
  6. Delete the contents of the malicious folder.

Step 3. Check program Startup

  1. Press Ctrl + Shift + Esc on your keyboard to open Windows Task Manager.
  2. Go to Startup tab.
  3. Right-click on the suspicious program and pick Disable.
    Startup

Step 4. Delete virus files

Malware-related files can be found in various places within your computer. Here are instructions that could help you find them:

  1. Type in Disk Cleanup in Windows search and press Enter.
    Disk cleanup
  2. Select the drive you want to clean (C: is your main drive by default and is likely to be the one that has malicious files in).
  3. Scroll through the Files to delete list and select the following: Temporary Internet Files
    Downloads
    Recycle Bin
    Temporary files
  4. Pick Clean up system files.
    Delete temp files
  5. You can also look for other malicious files hidden in the following folders (type these entries in Windows Search and press Enter): %AppData%
    %LocalAppData%
    %ProgramData%
    %WinDir%

After you are finished, reboot the PC in normal mode.

From our report of Jul 2019 · not reviewed since

Mr. Dec ransomware is a deadly virus that renders all personal files useless and threatens to delete the decryptor within specific time limit

Mr. Dec ransomware is cryptovirus that was first spotted in mid-May 2018, and since then was updated multiple times.

Hackers behind it use a variety of distribution methods, such as spam email, exploits, brute-force attacks, malicious ads, fake updates, and other tactics, so that more users would be susceptible for the infection.

Mr. Dec ransomware encrypts all personal data on the device with the help of AES encryption algorithm and appends . random 16 characters file extension, preventing from their further usage. Additionally, the malware drops a ransom note Decoding help.hta, which explains that users need to contact cybercrooks to have a chance of retrieving their data. Nevertheless, experts advise avoiding contact with them and urge users to remove Mr. Dec ransomware instead.

Hackers behind Mr. Dec ransomware used various email addresses and ransom notes - the latest variant drops Decoder.hta on the infected machines and prompts to contact bad actors via asist.help@protonmail.com or asist5000@tutanota.com emails. It is also known that the threat mainly targets businesses and formats all the backups, although regular users are affected as well.

Despite how threatening it might seem, we do not recommend you to contact the criminals in any way. According to the instructions, they should send you Mr. Dec's decryptor after you make the payment. Unfortunately, these are merely empty promises by hackers since they are only interested in blackmailing you for more money.

Thus, there is a high risk that you will be asked for more money once you pay for Mr.Dec ransomware authors. Here is the latest variant of the ransom note Decoder.hta which is displayed right after the malware finishes data encryption:

Note that criminals behind Mr.Dec ransomware are good at human psychology. Likewise, they put their victims under time pressure to make sure that they will agree to pay the ransom for locked files. However, we want to warn you that you do not necessarily need to make the transaction for data decryption, as you can get scammed or even be sent a malicious file instead of the decoder.

While there is currently no decryption tool for Mr.Dec ransomware available that would be able to help you with file recovery, you might want to try alternative solutions that we provide instructions for below.

Although, you must terminate Mr. Dec ransomware before starting data recovery. Even though many might think that they are experienced enough to deal with ransomware-type infections, only professionals or automatic tools can help you eliminate this cyber threat from your system.

Therefore, we strongly advise you to stay cautious and do not try manual Mr. Dec ransomware removal. It is highly dangerous and might put your computer's well-being at risk. Instead, you should install professional antivirus software and let it eliminate this ransomware automatically.

Mr. Dec: mr dec virus demands a ransom
Mr. Dec in our 2019 report.
Mr. Dec: mr dec ransomware virus
Mr. Dec in our 2019 report.

From our report of Jul 2019 · not reviewed since

Stay away from spam emails and adequately protect your computer from malware

In order to avoid ransomware attacks in the future, one must understand how it reaches the system in the first place.

Likewise, we advise you to stay away from malicious spam emails right away since it is the primary malware distribution source which can easily trick many novice computer users.

Usually, the sent emails look innocent and even legitimate, like coming from a well-known company as an invoice or another document. Unfortunately, this is merely a trick, and the attachment is holding the payload of the ransomware. Thus, if you open it, you automatically let the cyber threat inside your system.

Besides, you should also look into these protection methods that would reduce the infection chance to a minimum:

  • Equip your computer with anti-malware software and enable Firewall;
  • Install the ad-blocking application;
  • Update your Windows OS regularly, along with all the installed software on it;
  • Never download pirated software to cracks;
  • Avoid peer-to-peer networks and sites;
  • Use strong passwords for all your accounts;
  • Backup your files routinely.

From our report of Jul 2019 · not reviewed since

Safe Mr. Dec virus removal guide

As we have already mentioned, there is no other way how to remove Mr. Dec ransomware rather than get help from a professional.

For that, you can either see your local IT specialists or install a robust antivirus to help you complete the elimination procedure safely.

You can install , , or other security software, and it should complete Mr. Dec removal within several minutes. Nevertheless, be aware that new versions of the virus regularly emerge, so not all AV engines can catch it at all times. Also, anti-malware software is excellent for protecting computers from various other cyber threats that might try to enter the system.

Additionally, Virusi.bg experts say that if you are unable to download the malware removal program, there is a high risk that the ransomware is still active. Check the guidelines below and learn how to deactivate the malicious software to start the elimination procedure right away.

[GI=method-1]You should start the elimination of the ransomware by booting your computer into Safe Mode as shown below:

Experts have developed a professional software which is designed to help people recover files if they have accidentally lost them or in case of ransomware attack.

Windows Previous Versions feature might help you

Another great way to get back the access to the compromised files is to use an inbuilt Windows feature. Unfortunately, it requires System Restore function to be enabled before ransomware attack.

You might retrieve files using Shadow Explorer

If the malware hasn't corrupted or deleted Shadow Volume Copies from your computer, we highly advise you trying this tool.

There is no Mr. Dec ransomware decryptor available yet.

Mr. Dec: mr dec ransomware encrypted files extensions
Mr. Dec in our 2019 report.

Report it and recover your files

Report it

Report the attack even if you do not expect the files back: insurers and banks ask for the report number, and police use the contacts in the note to link cases.

United States
FBI IC3 · FTC ReportFraud

Give the victim ID, the note and the date the files were encrypted. A business that holds personal data may also have to notify its data protection authority, in the EU within 72 hours.

Backups: the 3-2-1 rule

Keep three copies of files that matter, on two kinds of storage, with one copy offline or off-site.

A disk that stays plugged in is reached by malware like Mr. Dec together with the PC; one you connect only for the backup is not.

On Windows 11, File History keeps versions on an external drive, and OneDrive keeps earlier versions of synced files. Before restoring anything, make sure the PC no longer shows ransom notes called help.hta in every folder.

Setting it up step by step: 3-2-1 backups on Windows 11 and 10.

Do not let government spy on you

The government has many issues in regards to tracking users' data and spying on citizens, so you should take this into consideration and learn more about shady information gathering practices.

Avoid any unwanted government tracking or spying by going totally anonymous on the internet.

You can choose a different location when you go online and access any material you want without particular content restrictions. You can easily enjoy internet connection without any risks of being hacked by using VPN.

Control the information that can be accessed by government any other unwanted party and surf online without being spied on. Even if you are not involved in illegal activities or trust your selection of services, platforms, be suspicious for your own security and take precautionary measures by using the VPN service.

Backup files for the later use, in case of the malware attack

Computer users can suffer from data losses due to cyber infections or their own faulty doings.

Ransomware can encrypt and hold files hostage, while unforeseen power cuts might cause a loss of important documents. If you have proper up-to-date backups, you can easily recover after such an incident and get back to work. It is also equally important to update backups on a regular basis so that the newest information remains intact - you can set this process to be performed automatically.

When you have the previous version of every important document or project you can avoid frustration and breakdowns. It comes in handy when malware strikes out of nowhere. Use for the data restoration process.

Questions about Mr. Dec ransomware

Should I pay the ransom in help.hta?

Not before you have tried everything else. Identify the family from help.hta and one encrypted file, check No More Ransom for a free decryptor, and look for clean copies in OneDrive, backups and Previous Versions.

Paying funds further attacks, may be illegal if the group is sanctioned, and is no promise of a working key: many victims get partial or broken decryption. If you consider paying for business-critical data, involve the police and a professional incident responder first, and never pay through intermediaries who promise their own decryption.

Is there a free Mr. Dec decryptor?

We last checked on 7 October 2026, and for Mr. Dec no free decryptor is known. We check No More Ransom, which collects free tools from police and security companies, and the decryptor pages of the major antivirus vendors. A working decryptor exists only when the encryption has a flaw or the keys were leaked or seized.

Ignore sites and videos that offer a "Mr. Dec decryptor" for download or for a fee: these are usually scams or malware. Real decryptors are free and come from known security companies or law enforcement. Keep the encrypted files in case a tool appears later.

Did Mr. Dec steal my files or passwords?

We do not know yet. Nothing published so far shows data theft by Mr. Dec, but the only confirmed sign is ransom notes called help.hta in every folder, which says nothing about what happened before. Many current ransomware attacks copy files or run a password stealer first, so it is wise to act as if they did.

From a clean device, change the passwords that were saved in the browsers on this PC, starting with e-mail and banking, sign out of all sessions and turn on two-step verification. Watch bank statements and account activity for the next few weeks.

How did Mr. Dec get on my computer?

The way Mr. Dec spreads has not been documented yet, so look at your own recent activity. On home PCs, ransomware most often comes with cracked programs, game cheats, key generators and fake updates, or with an e-mail attachment that was opened.

On business networks, attackers usually log in through Remote Desktop with a stolen or guessed password. Think back to what was downloaded or installed in the days before ransom notes called help.hta in every folder, and check the Downloads folder and Installed apps sorted by date. Keep anything suspicious for your report, but do not run it again.

Are ransomware recovery services legitimate?

Some are, but read the offer carefully. Genuine data-recovery firms recover deleted originals from disks or rebuild damaged files, and they say so. Others promise to "decrypt any ransomware" for a fixed price, which is impossible without the key; they quietly pay the attackers and keep a margin, sometimes without telling the victim.

Be especially careful with services that contact you after you post about the attack online. Ask for references, a written method and a no-result-no-fee clause, and check the free tools on No More Ransom first.

Is Mr. Dec the same as other ransomware with a similar name?

Not necessarily. Ransomware names come from the file extension, the note or a word in the code, so unrelated families often end up with similar names, and one family can appear under several names. The difference matters: a decryptor or advice for one family does not fit another and can damage files.

Compare the ending added to your files and the exact name of the note with the summary table at the top of this guide, then upload the note and one encrypted file to ID Ransomware from a clean device. If the result names another family, follow the guide for that family instead.

Can I delete help.hta?

Yes, the note itself is harmless text and deleting it does not affect your files. Keep at least one copy first, outside the infected PC. help.hta contains your personal ID and the attackers' contact details, which identification services use to tell which family encrypted your files, and which a decryptor may need later.

Police reports also ask for it. Once you have saved a copy, you can remove the notes from every folder after the ransomware program has been removed and your files are restored or backed up.

Can System Restore bring my files back?

No. System Restore rolls back Windows settings, drivers and programs, not documents and photos, so it does not decrypt anything. What can help is Previous Versions, which uses the same shadow copies: right-click a folder, choose Properties > Previous Versions and see if snapshots from before the attack are listed.

Most ransomware deletes them, but some attacks fail to. If snapshots exist, copy the old versions to another drive instead of restoring over the encrypted files. Do this only after the ransomware is removed.

How do I open my .docx, .jpg and other files locked by Mr. Dec?

You cannot open locked files normally while they stay encrypted, and renaming them will not help. Our earlier report did not record the extension that Mr. Dec adds, so check one locked file name and the ransom note for it.

No free decryptor is known for this variant; check No More Ransom (nomoreransom.org) for updates. Do not rename the files, change the extension or edit them, because that can make recovery harder. Copy the locked files to an external drive before you clean the system, so a decryptor released later still has them.

Will Fortect remove Mr. Dec?

Fortect scans Windows for malware and unwanted programs and repairs the system files and settings they change, and its free scan shows what it finds on your PC before you decide anything.

For Mr. Dec, follow the plan above as well: the browser steps take back permissions and settings that no scanner treats as a threat, and uninstalling the program that brought it removes the source.

Run Microsoft Defender's full scan and, if anything was found, its offline scan as a second opinion. If the symptoms are gone after the plan and both scans are clean, there is nothing more to do.

Sources

More removal guides

Questions and experiences: Mr. Dec ransomware

Still seeing it, or found something we did not cover? Ask here: members and our editors answer. Reading is open; writing needs a free account.

0 comments

…

5,600 members already hereReading, writing, commenting and voting. 0 verified · 325 joined this year