NoMatter Ransomware Virus: How to Remove It and Recover Files Without Extensions

NoMatter is ransomware that encrypts documents, photos, databases and archives without adding a recognizable extension. Files keep their original names but stop opening, making the attack less obvious than ransomware that renames everything.

The malware changes the desktop wallpaper and leaves README.txt together with Decryptor.exe. If those files appear, isolate the computer before opening more documents or connecting a backup drive.

NoMatter Ransomware Overview

NoMatter is a Windows file-encrypting threat built to extort victims. It processes valuable files and leaves their filenames unchanged. A file can still be called family-photo.jpg or accounts.xlsx, yet its internal data has been transformed and the normal application cannot read it. This behavior can confuse users who expect every ransomware infection to add a strange suffix.

The malware drops a text ransom note named README.txt and a program called Decryptor.exe. The note claims files were protected with AES-256 encryption and tells the victim to send a unique ID through the Telegram handle @UNBLOCK_COMPUTER. The criminals say they will provide a key that must be entered into Decryptor.exe.

The bundled decryptor is part of the extortion workflow, not a trusted recovery utility. Running it without a verified key does not make the system safe, and deleting it does not reverse the encryption. Preserve a copy for qualified incident responders, but do not experiment with it on the original encrypted files.

What makes NoMatter different

• Encrypted files keep their original extensions and names.
• The desktop wallpaper is changed after the attack.
• README.txt contains the ransom instructions and victim ID.
• Decryptor.exe is left beside the note as the attacker’s recovery program.
• The message directs victims to a Telegram account.
• A few small files may be offered for free test decryption.

No public decryptor was identified for the analyzed variant. That does not make payment a safe recovery method. Criminals may send no key, provide a tool that damages data or demand additional money. Removal and file recovery are separate tasks: the malware must be eliminated first, while encrypted data should be preserved for restoration from backups or future analysis.

The unchanged filenames also make scoping and recovery more difficult. Backup software may copy the newly encrypted versions because they still look like ordinary documents, while users can overwrite cloud history by repeatedly opening or saving damaged files. Modification times, failed preview thumbnails and application errors become important clues when identifying which copies were affected.

How the NoMatter Ransomware Attack Works

Step 1: A malicious file is launched

NoMatter can be delivered through a phishing attachment, archive, fake installer, cracked program, malicious ad or downloader trojan. The file may appear to be a routine document or software package until it is opened.

Step 2: The ransomware searches for valuable files

It looks for data that would hurt to lose, including documents, spreadsheets, photos, databases and archives. Any connected drive or shared folder writable by the infected account can also be placed at risk.

Step 3: Contents are encrypted without renaming files

The ransomware changes the data inside each targeted file but preserves the filename. Windows may continue showing familiar icons and extensions, while applications report corruption, unsupported format or an inability to open the file.

Step 4: The wallpaper and ransom artifacts appear

NoMatter changes the desktop background and creates README.txt. It also leaves Decryptor.exe, which the note presents as the program needed to enter an attacker-supplied key.

Step 5: The victim is pushed to Telegram

The note provides a unique victim ID and asks the user to contact @UNBLOCK_COMPUTER. Offering a sample decryption is intended to establish trust and move the victim into a private negotiation.

Step 6: The criminal controls the recovery path

The attackers claim that only their key will work with Decryptor.exe. This places every part of the proposed solution under criminal control, including the price, the software and whether a usable key is ever delivered.

How to Recognize NoMatter Ransomware

• Previously normal files retain their names but no longer open.
• README.txt appears on the desktop or inside affected folders.
• Decryptor.exe appears without having been intentionally installed.
• The desktop wallpaper changes to a ransomware warning.
• The ransom note mentions AES-256 and @UNBLOCK_COMPUTER.
• Many files are modified within a short period even though their names do not change.
• Connected drives or network folders begin showing unreadable content.
• Security software reports ransomware or a file cryptor.

Because NoMatter does not add an extension, confirm the scope by file modification times, security alerts and application errors. Do not assume that a file is healthy simply because its name looks normal.

What to Do If NoMatter Encrypted Your Files

Disconnect the computer and attached storage

Turn off network connectivity and unplug external drives. Disconnect mapped shares from the affected account. If a business network is involved, isolate the device through network controls so the infection cannot reach additional systems.

Do not run Decryptor.exe on the originals

The file belongs to the ransomware operation. Preserve it for identification, but do not treat it as trusted software or submit valuable originals to an unverified key. Work only with duplicate copies inside an isolated environment.

Preserve the note, victim ID and sample files

Keep README.txt, Decryptor.exe and several small encrypted files. Record the first time files stopped opening and save security alerts. These artifacts can help identify the exact variant and determine whether a legitimate recovery tool becomes available.

Change exposed credentials from another device

Ransomware can arrive with password stealers or after an account compromise. Reset email, remote-access, cloud and administrative credentials from a clean system. Revoke active sessions and inspect for unfamiliar accounts or forwarding rules.

Scan and rebuild the affected system

Use reputable security software to identify the payload and related malware. For important systems, a clean Windows reinstall is safer than relying on the deletion of one file. Close the original entry point before reconnecting restored data.

Protect backups before restoration

Do not connect backup media until the operating system is clean and the attack has been contained. Pause synchronization services that may overwrite healthy cloud versions with encrypted copies. Verify backup dates against the earliest suspicious activity.

Check every location the account could modify

Review mapped drives, shared folders, removable media and synchronized cloud directories. NoMatter’s lack of a new extension means a simple filename search will miss affected data. Compare hashes, modification times and file-opening results on duplicate copies to establish the real scope.

If you suspect your computer is infected with malware — slow performance, pop-ups, redirects, or programs you don’t recognize — follow the free step-by-step removal guide below to find and remove it.

Remove Malware from Windows [Step-by-Step Guide]

• STEP 1: Uninstall malicious programs from Windows
• STEP 2: Reset browsers back to default settings
• STEP 3: Use Rkill to terminate suspicious programs
• STEP 4: Use Malwarebytes to remove Trojans and unwanted programs
• STEP 5: Use HitmanPro to remove rootkits and other malware
• STEP 6: Use AdwCleaner to remove malicious browser policies and adware
• STEP 7: Perform a final check with ESET Online Scanner

STEP 1: Uninstall malicious programs from Windows

First, we’ll manually check your computer for unknown or malicious programs. Adware and browser hijackers often have a working uninstall entry — removing them this way takes care of the easy part before we run the scanners.

With the malicious programs removed, you’re ready for the next step in this guide.

STEP 2: Reset browsers back to default settings

In this step, we will remove spam notifications,  malicious extensions, and change to default any settings that might have been changed by malware.
Please note that a Chrome or Edge reset turns off all your extensions, and a Firefox refresh removes them. Your bookmarks and favorites stay intact. For each browser that you have installed on your computer, please click on the browsers tab below and follow the displayed steps to reset that browser.

STEP 3: Use Rkill to terminate suspicious programs

Next, we’ll download and run Rkill to stop any suspicious processes running in the background. This prevents the malware from interfering with the removal tools in the following steps.

RKill is a program that was developed at BleepingComputer.com that attempts to terminate known malware processes so that your normal security software can then run and clean your computer of infections. When RKill runs it will kill malware processes and then removes incorrect executable associations and fixes policies that stop us from using certain tools.

1. Download Rkill.

   You can download RKill to your computer from the below link. When at the download page, click on the Download Now button labeled iExplore.exe. We are downloading a renamed version of Rkill (iExplore.exe) because some malware will not allow processes to run unless they have a certain filename.

   

   RKillStops malware processes so other tools can run

   Download RKillOpens the BleepingComputer download page in a new tab.

2. Run RKill.

   After downloading, double-click the iExplore.exe icon to kill malicious processes. In most cases, downloaded files are saved to the Downloads folder.
   The program may take some time to search for and end various malware programs.

   

   When it is finished, the black window will close automatically and a log file will open. Do not restart your computer. Proceed to the next step in this guide.

STEP 4: Use Malwarebytes to remove Trojans and unwanted programs

Now we’ll install Malwarebytes and run a full scan to detect and remove infections, adware, and potentially unwanted programs from your computer.

Malwarebytes is one of the most popular and trusted anti-malware tools for Windows — and it’s completely free for removing infections. It catches threats that many antivirus programs miss, including adware, browser hijackers, and trojans. Follow the steps below to scan your PC and remove what Malwarebytes finds.

1. Download Malwarebytes

   Click the button below to download the latest version of Malwarebytes for Windows from the official source. The free version is all you need — it will scan your computer and remove adware, browser hijackers, and other malicious software at no cost.

   

   Malwarebytes Free for WindowsScans and removes malware at no cost

   Download MalwarebytesOfficial installer for Windows 11 and 10. Your download starts right away.Want real-time protection? See Malwarebytes Premium

2. Install Malwarebytes

   When the download finishes, open your Downloads folder and double-click the MBSetup file. If Windows shows a User Account Control pop-up, click “Yes” to allow the installation.

   

3. Follow the On-Screen Prompts to Install Malwarebytes

   The setup wizard will walk you through a few quick screens:

   • Choose where you’re installing the program — “Personal Computer” or “Work Computer” — then click Next.

     

   • Malwarebytes will now install on your device. This usually takes under a minute.

     

   • When installation is complete, the “Welcome to Malwarebytes” screen will open automatically.

     

   • On the final screen, click Open Malwarebytes to launch the program.

     

4. Optional: Check for rootkits with a Custom Scan

   You don’t need to change any settings for a normal scan. The standard Threat Scan in the next step is enough for most problems, so you can go straight to it.

   If you also want to check for rootkits, use a Custom Scan. In current versions of Malwarebytes, rootkit scanning is only available there:

   1. On the Scanner tile, click the three-dot menu and select Advanced Scan.
   2. Choose Custom Scan. In its options, check Scan for rootkits.
   3. Select your system drive (usually C:\) as the location to scan, then start the scan. It takes longer than a Threat Scan.
   4. When it finishes, review and quarantine the results as described in the steps below.

   Rootkit scanning isn’t available on Windows devices with ARM processors.

5. Start the Scan

   Click the blue Scan button. Malwarebytes will automatically update its virus database and start checking your computer for malware.

   

6. Wait for the Scan to Finish

   The scan checks your entire system for browser hijackers and other malicious programs, so it can take 5 to 20 minutes depending on your computer. Feel free to do something else — just check back occasionally to see the progress.

   

7. Quarantine the Detected Threats

   When the scan is done, you’ll see a list of everything Malwarebytes found — malware, adware, and potentially unwanted programs. Click the “Quarantine” button to remove all of them at once.

   

   Malwarebytes will now remove the malicious files and registry entries and move them safely into quarantine.

   

8. Restart Your Computer

   Some threats can only be fully removed after a reboot. If Malwarebytes asks you to restart, click Yes. Once you’re logged back in, Malwarebytes has finished removing the threats it found.

   

STEP 5: Use HitmanPro to remove rootkits and other malware

Next, we’ll run a second-opinion scan with HitmanPro to catch Trojans, rootkits, and other malicious programs that may have survived the previous step.

HitmanPro is a second-opinion scanner — it’s designed to catch what your main antivirus might have missed. Instead of relying on a single detection engine, it checks the behavior of files in the locations where malware usually hides. Anything suspicious is checked online, where it’s analyzed by several antivirus engines in HitmanPro’s Scan Cloud.

Good news: scanning is completely free, with no limits. You only need a license when it’s time to remove what was found — and even then, you can activate a free one-time 30-day trial to remove what it finds at no cost. The trial works once per computer. After that, removal needs a paid license, and the purchase screen shows the current price.

1. Download HitmanPro

   Click the button below to download HitmanPro. Remember — the scan is free, so you have nothing to lose by checking your PC.

   

   HitmanProSecond-opinion malware scanner from Sophos

   Download HitmanProFree scan. Removing threats needs the free 30-day trial. Opens the official HitmanPro page in a new tab.

2. Install HitmanPro

   When the download finishes, open your Downloads folder and double-click the file “hitmanpro_x64.exe”. (On 32-bit Windows 10, the file is named “hitmanpro.exe”.)

   

   If a User Account Control pop-up asks whether HitmanPro can make changes to your device, click “Yes” to continue.

   

3. Follow the On-Screen Prompts

   On the HitmanPro start screen, click “Next” to begin the system scan. No lengthy setup required — it goes straight to work.

   

   

4. Wait for the Scan to Finish

   HitmanPro will now check your computer for malicious programs. This usually takes just a few minutes thanks to its cloud-based scanning.
   

5. Review the Results and Click “Next”

   When the scan is done, HitmanPro will show you everything it found. Click “Next” to remove the detected threats.

   

6. Click “Activate Free License”

   To remove the malicious files, click the “Activate free license” button. This starts your free 30-day trial — no payment details needed — and unlocks the full cleanup.
   

   When the removal is complete, HitmanPro will show a summary of everything it cleaned. Click Next, then click Reboot if prompted. If there’s no reboot prompt, click Close. Then check whether the problems you noticed have stopped. If they come back, save the HitmanPro log and ask for help in our forum.

STEP 6: Use AdwCleaner to remove malicious browser policies and adware

We’ll now use AdwCleaner to remove malicious browser policies and unwanted browser extensions — the leftovers that keep hijacking your browser settings even after the malware itself is gone.

AdwCleaner is a free on-demand scanner that specializes in adware, browser hijackers, and unwanted toolbars — the exact threats that mainstream antivirus programs often miss. It also includes tools that repair the damage malware leaves behind, like hijacked browser settings and malicious policies. It’s a quick scan that’s well worth running.

1. Download AdwCleaner

   Click the button below to download AdwCleaner — it’s free, portable, and requires no installation.

   

   Malwarebytes AdwCleanerRemoves adware and unwanted programs at no cost

   Download AdwCleanerOpens the official download page in a new tab.

2. Run AdwCleaner

   Open your Downloads folder and double-click the file named “adwcleaner.exe“. There’s no installation — the program starts right away.
   

   If Windows asks whether you want to allow AdwCleaner to run, click “Yes“. When the license agreement appears, click I agree to continue.

   

3. Leave “Reset Chrome policies” off unless you need it

   AdwCleaner can reset Chrome policies, the settings that malware sometimes uses to lock your browser so you can’t change it back. This option removes every Chrome policy, including legitimate ones set by an employer, a school, or parental-control software, so leave it off for a normal scan.

   AdwCleaner applies this option only if you run Basic Repair at the end of the cleanup. Malwarebytes advises running Basic Repair only when a support agent asks you to, and it also runs every other repair action that is turned on in the same list. If this is your own personal PC and chrome://policy in Chrome lists policies you didn’t set, ask for help in our forum instead. On a work or school computer, ask the IT administrator.

4. Start the Scan

   Click “Dashboard” on the left side of the window, then click the “Scan Now” button.

   

5. Wait for the Scan to Finish

   AdwCleaner will now check your computer for adware and other malware. This usually takes only a few minutes — it’s one of the fastest scanners around.

   

6. Quarantine the Detected Threats

   When the scan finishes, AdwCleaner lists everything it found. Review the list and uncheck any program you installed on purpose and want to keep, then click Next. If AdwCleaner also found preinstalled software, it shows that list next. Review it the same way, then click “Quarantine“. Older versions show the Quarantine button on the first list, as in the image below.

   

7. Click “Continue” to Finish the Cleanup

   Save any open work first — AdwCleaner needs to close your open programs before it can clean. When you’re ready, click the “Continue” button.
   

   AdwCleaner will now move the selected items to quarantine. If it asks you to restart your PC, allow it. When you’re back in Windows, AdwCleaner may offer a Basic Repair. Click Skip Basic Repair. Malwarebytes recommends running Basic Repair only when a support agent asks you to. Then check whether the problems you noticed have stopped.

STEP 7: Perform a final check with ESET Online Scanner

Finally, we’ll run ESET Online Scanner as a last check for anything the earlier scans missed. A clean result is a good sign, but no scanner can guarantee that a computer is malware-free.

ESET Online Scanner is a free second-opinion scanner that performs a deep, full-system check for viruses, trojans, rootkits, and other malware. We use it as the final step because it’s thorough and can catch threats the earlier scans missed. A clean result is a good sign, but no scanner can guarantee that a computer is malware-free.

1. Download ESET Online Scanner

   Click the button below to download ESET Online Scanner.

   

   ESET Online ScannerFree one-time malware scan from ESET

   Download ESET Online ScannerOpens the official download page in a new tab.

2. Run the Installer

   When the download finishes, open your Downloads folder and double-click “esetonlinescanner.exe“.
   

3. Install ESET Online Scanner

   On the start screen, select your language from the drop-down menu and click Get started.

   

   On the Terms of use screen, click Accept.
   

   Choose your preferences for the Customer Experience Improvement Program and the Detection feedback system (either choice is fine), then click Continue.
   

4. Start a Full Scan

   Click Full Scan — this checks your entire computer, not just the common hiding spots.

   

   Select Enable for Detection of Potentially Unwanted Applications — this lets ESET catch adware and bundled junk programs, not just viruses. Then click Start scan.

   

5. Wait for the Scan to Finish

   ESET will now check every file on your computer. Because it’s a full scan, this can take a while — often an hour or more, depending on how much data you have. Leave it running in the background and check on it from time to time.

   

6. Review the Results

   When the scan completes, the Found and resolved detections screen appears. Detected threats are usually cleaned and quarantined automatically. Click View detailed results to see exactly what was removed, and ask for help in our forum if any item could not be cleaned.
   

   If ESET found nothing, restart your computer and check whether the problems you noticed have stopped. If they continue, ask for help in our forum.

When you’ve finished these steps, check whether the problems you noticed have stopped. If they continue, see the options below.

If you are still having problems with your computer after completing these instructions, then please follow one of the steps:

• Run a computer scan with ESET Online Scanner
• Ask for help in our Windows Malware Removal Help & Support forum.

Can Files Encrypted by NoMatter Be Recovered?

Restore from a verified backup

A clean backup created before the infection is the safest recovery source. Restore into an isolated environment first, scan the files and confirm they open correctly before returning the system to normal use.

Use cloud version history and unaffected copies

Cloud services may retain earlier versions even when the latest synchronized copy is encrypted. Email attachments, exported reports, colleague devices and disconnected media may also contain unaffected originals.

Keep an untouched encrypted copy

Future analysis may discover a weakness or obtain keys. Store copies of representative encrypted files, README.txt and the malware sample on offline media. Do not repeatedly test random repair utilities against the only copy.

Verify any claimed decryptor

Use established security organizations and match the ransomware by note, behavior and sample identifiers. A website promising instant NoMatter recovery may simply collect payment, upload private files or install more malware.

Understand the limits of paying

A working sample decryption does not guarantee the rest of the data can be restored. The attackers can disappear, send an incorrect key or demand more money. Payment also encourages further attacks and may create legal or compliance issues for an organization.

How to Prevent NoMatter and Similar Ransomware

• Keep offline or immutable backups and test restoration regularly.
• Show file extensions in Windows, but remember that NoMatter does not add one.
• Do not open unexpected archives, executables or macro-enabled documents.
• Avoid cracked software, unofficial activation tools and untrusted download sites.
• Patch Windows, browsers, remote-access tools and internet-facing applications.
• Use multi-factor authentication for email, VPN and administrator accounts.
• Limit write access to shared folders and backup locations.
• Monitor rapid file modifications even when filenames stay unchanged.
• Keep security software enabled and updated on every endpoint.

The Bottom Line

NoMatter ransomware can hide the scale of an attack by leaving filenames unchanged. The strongest clues are unreadable files, the changed wallpaper, README.txt and the unexpected Decryptor.exe program.

Isolate the system, protect backups, preserve the evidence and remove the malware before attempting recovery. Do not run the attacker’s decryptor casually or assume a Telegram negotiation will return your files.