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What is ProLock?
Discovered by PeterM, ProLock is a rebranded version of PwndLocker ransomware. This ransomware encrypts files with the RSA-2048 algorithm, modifies filenames and creates a ransom message. ProLock appends the ".proLock" extension to the filenames of all encrypted files.
Research shows that it appends this extension several times, which might also indicate that it encrypts files several times. It creates ransom messages in the "[HOW TO RECOVER FILES].txt" files, which victims can find in folders that contain encrypted data.
The ransom messages that ProLock creates state that victims can retrieve their files by paying a ransom. Instructions about how to pay this are provided on a Tor website - a link to the relevant page can be found in each "[HOW TO RECOVER FILES].txt" text file.
This Tor page contains a Bitcoin wallet address to transfer cryptocurrency to ProLock's developers. At the time of research, cost of decryption was 60 BTCs, however, each victim may be asked to pay a different sum of Bitcoins. In any case, it is made clear that decryption without a payment is impossible.
Victims are warned not to try to modify files or decrypt them with third party software, since this might cause permanent data loss. ProLock's developers encourage people to pay the ransom immediately, as decryption keys are stored on a remote server for one month only.
They claim that they have gathered some sensitive information, and threaten to share it unless victims pay the ransom. Only the cyber criminals who designed the ransomware have the correct decryption tools. Note that most criminals do not send these tools, even if they are paid.
By paying the ransom, victims lose their data and money. Therefore, never pay any cyber criminals. Unfortunately, there is no way to decrypt files free of charge without tools held only by ProLock's developers. In such cases, files can only be recovered by restoring them from a backup.
Note that uninstalling ransomware prevents further data loss (encryption), however, it does not regain access to encrypted files (they remain encrypted).
Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:
![ProLock decrypt instructions ([HOW TO RECOVER FILES].txt)](/images/stories/screenshots202003/prolock-ransom-note.jpg)
Generally, programs such as ProLock encrypt files and keep them inaccessible unless victims decrypt them with specific tools that can only be purchased from the developers. Main variables are ransom size and cryptographic algorithm (symmetric or asymmetric) that ransomware uses to encrypt data.
Some examples of other ransomware-type programs include Gate, LX and Tongda2000. Unfortunately, it is impossible to decrypt files without paying the ransom for tools/keys (not advised), unless ransomware contains bugs/flaws and is not fully developed.
Data loss caused by ransomware can be avoided by restoring files from a backup, which should be maintained on a remote server or unplugged storage device.
How did ransomware infect my computer?
Cyber criminals spread malware through Trojans, spam campaigns (emails), fake software updaters, software 'cracking' tools and dubious file and/or software download channels. Trojans are programs that can cause chain infections: if installed, they can install more malicious programs.
When cyber criminals use spam campaigns to spread malware, they send emails that contain a malicious attachment (or website link that downloads the malicious file). Malicious software is installed when recipients open a malicious attachment/file (or a file downloaded through a link).
Cyber criminals commonly send emails that contain a malicious Microsoft Office document, archive file (ZIP, RAR), executable file (.exe), PDF document or JavaScript file. Fake software updating tools usually infect systems by exploiting bugs/flaws of outdated software installed on the operating system, or by installing malware rather than updates and fixes.
Unofficial activation tools infect systems in a similar way: rather than activating licensed software free of charge, they install malicious software.
Unofficial websites, free file hosting, freeware download websites, third party downloaders, Peer-to-Peer networks (e.g., torrent clients, eMule) and other similar download channels host malicious files - downloading and opening them causes installation of malware.
| Name | ProLock virus |
| Threat Type | Ransomware, Crypto Virus, Files locker. |
| Encrypted Files Extension | .proLock |
| Ransom Demand Message | [HOW TO RECOVER FILES].txt |
| Ransom Amount | At the time of research, the ransom was 60 Bitcoins, however, this might vary. |
| BTC Wallet Address | 1LVLHAs4Vq9Yt9nHvvrgw9djtA7BiR8sKM, 1NCFTWLhsWqjm4dBaWJPn7QARDwekaqzUj |
| Cyber Criminal Contact | support981723721@protonmail.com, chec1kyourf1les@protonmail.com |
| Detection Names | Avast (Win32:Evo-gen [Susp]), BitDefender (Trojan.Peed.Gen), ESET-NOD32 (A Variant Of Win32/Filecoder.PwndLocker.A), Microsoft (Trojan:Win32/Wacatac.D!ml), Full List Of Detections (VirusTotal) |
| Rogue Process Name | NAS_0.EXE (its name may vary) |
| 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 | A ransom must supposedly be paid through a Tor website. |
| 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) |
To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. Download Combo CleanerTo use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com. |
How to protect yourself from ransomware infections
Installed programs must be updated and activated through implemented functions and/or tools that are provided by official developers. Third party, unofficial tools can distribute malicious software. Furthermore, it is illegal to activate licensed programs with unofficial activation ('cracking') tools.
Attachments and web links in irrelevant emails received from suspicious, unknown addresses should not be opened. There is a high probability that they might be sent by cyber criminals. Therefore, email contents should be opened only when you are certain they will not cause damage.
All files should be downloaded from official ant trustworthy websites, and via direct links. Other tools are often used to proliferate malicious software (examples of untrusted channels are provided above). Regularly scan the operating system for threats with reputable antivirus or anti-spyware software and remove detected threats immediately.
Keep this software up to date. If your computer is already infected with ProLock, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.
Text presented in ProLock ransomware text file ("[HOW TO RECOVER FILES].txt"):
Your files have been encrypted by ProLock Ransomware using RSA-2048 algorithm.
[.:Nothing personal just business:.]
No one can help you to restore files without our special decryption tool.
To get your files back you have to pay the decryption fee in BTC.
The final price depends on how fast you write to us.1. Download TOR browser: hxxps://www.torproject.org/
2. Install the TOR Browser.
3. Open the TOR Browser.
4. Open our website in the TOR browser: msaoyrayohnp32tcgwcanhjouetb5k54aekgnwg7dcvtgtecpumrxpqd.onion
5. Login using your ID -***If you have any problems connecting or using TOR network:
contact our support by email support981723721@protonmail.com[You'll receive instructions and price inside]
The decryption keys will be stored for 1 month.
We also have gathered your sensitive data.
We would share it in case you refuse to pay.Decryption using third party software is impossible.
Attempts to self-decrypting files will result in the loss of your data.
ProLock Tor website (GIF):
Text in this page:
Hello, you are a victim of ProLock ransomware.
Your files have been encrypted using RSA2048 algorithm.
This algorithm is one of the strongest, it is impossible to decrypt files without known key.
As you understand, situation is very important.
You can decrypt 1-2 files for free as a proof of work.
We know that this computer is very valuable for you.
So we will give you appropriate price for recovering.
DON'T try to change files by yourself, DON'T use any third party software for restoring your data or antivirus solutions - these actions may entail damage of the private key and, as result, the loss of all your data.
All your sensitive data was downloaded on remote servers. If you do not pay in several days all these sensitive files will be published in social networks and public media.
To get your files unlocked, pay.
If you want to make test unlock, contact support.
Payment information
60 BTCUNPAID
Send 60 BTC (in ONE payment) to:
don't include transaction fee in this amount
1LVLHAs4Vq9Yt9nHvvrgw9djtA7BiR8sKM
Available once every 12 hours
Screenshot of files encrypted by ProLock (".proLock" extension):
Update 15 May 15 2020 - The developers of ProLock ransomware have started cooperating with QakBot (QBot) Trojan to increase the number of infections. QakBot is a banking Trojan injected via malicious documents that are distributed via spam email campaigns.
Once infiltrated, QakBot connects to a remote server (at the time of research, this was cloud storage) and downloads and executes a batch of scripts, rather than simply injecting ProLock by itself. In this way, QakBot operates as a 'gateway'.
Update August 28, 2020 - Cyber criminals have recently released an updated variant of ProLock ransomware which appends a different file extension - ".pr0Lock". The ransom note and website remain identical. The only differences are contact email (chec1kyourf1les@protonmail.com) and size of ransom (255 Bitcoins instead of 60) as well as the cryptowallet address.
Screenshot of files encrypted by this ProLock ransomware variant (".pr0Lock" extension):
ProLock ransomware removal:
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Removal and file recovery procedure
If your files are encrypted with a new extension and a ransom note has appeared, you've been hit by ransomware. Don't pay. The procedure below works in order: contain the infection, identify the variant, remove the ransomware itself (so anything you restore doesn't get re-encrypted), and try to recover files using free decryption tools, Windows Volume Shadow Copies, or backups. Run a full system scan with Combo Cleaner to remove the infection - then move on to file recovery.
Common ransomware behaviors
VisibleEncrypts your files and renames them
The ransomware reads each file, encrypts the contents with the attacker's public key, and writes the encrypted bytes back to disk. Most variants also rename the file by appending a new extension - .net, .locked, .crypt, .lockbit, .djvu, etc. Without the matching private key, the encrypted files cannot be opened normally. Recovery depends on a free decryption tool, a recoverable Volume Shadow Copy, or a clean backup.
VisibleDrops a ransom note in every encrypted folder
A text or HTML file (usually named HOW_TO_DECRYPT.txt, README.txt, _readme.txt, or similar) is placed in every folder that contains encrypted files. The note explains the situation, lists a payment amount in cryptocurrency, gives a deadline, and provides a contact email or .onion site. Save the note - don't delete it. Its exact wording, the email address, and the bitcoin wallet are how you identify the variant in the next phase.
VisibleReplaces the desktop wallpaper
Many ransomware variants change the Windows wallpaper to a black or red image with the ransom message and instructions. The wallpaper is just a visual scare tactic - it doesn't add any actual capability and reverts to normal once the ransomware is removed. Photograph it before removal in case the contact details are useful for variant identification or for reporting to authorities.
HiddenDeletes Volume Shadow Copies
One of the first things modern ransomware does after launching is run vssadmin delete shadows /all /quiet to wipe Windows' built-in Volume Shadow Copies - the snapshots that Previous Versions and System Restore rely on. Some ransomware doesn't fully succeed (especially on systems where the user lacks full admin rights), leaving partial shadow copies recoverable. Phase 4 step 11 covers how to check what survived.
HiddenDisables Windows Defender and other security tools
Before encrypting, the ransomware tries to silence anything that could alert you or block it - Windows Defender real-time protection, third-party antivirus services, backup agents (Veeam, Acronis), and sometimes the Windows Event Log service. It often modifies Group Policy or registry keys to keep these off after reboot. Phase 3 step 9 explicitly turns Tamper Protection back on so the next ransomware attempt can't repeat the trick.
HiddenSpreads laterally to other PCs on the network
Network-aware ransomware (LockBit, Conti, BlackCat, Akira families) doesn't stop at the first machine. It scans for SMB shares, mapped drives, and other PCs on the same network, then encrypts whatever it can reach. On Windows domains, a single compromised user with admin rights can lead to all-domain encryption. This is why Phase 1 step 2 disconnects the network as the very first action - it stops the spread immediately.
HiddenSteals data before encrypting (double extortion)
Modern ransomware (LockBit, BlackCat / ALPHV, Akira, Cl0p, Royal) almost always exfiltrates data before encrypting. The attacker then runs a "double extortion" play: pay the ransom for decryption, plus pay again to prevent the stolen data from being leaked on the group's leak site. Paying the first ransom does not get the leaked data back - assume that anything the ransomware could read was uploaded. This is one more reason not to pay: the data is already out.
Don't pay the ransom
Paying the ransom does not guarantee you'll get your files back. Major ransomware response studies consistently show that a meaningful percentage of paying victims either receive a non-working decryptor, only partial decryption, or no decryptor at all. Beyond that:
- Paying confirms you as a willing target - re-attack rates within 12 months are high
- Several ransomware groups have been sanctioned (US OFAC, UK OFSI). Paying these groups may be illegal under sanctions law in your country
- The ransom funds the next attack - on you or someone else
- Modern ransomware almost always exfiltrates data first, so paying doesn't get the leaked data back. Assume anything the malware could read was uploaded
- Decryptors, even when they work, often leave files corrupted because the encryption itself was buggy or rushed
The path below tries every legal, free recovery option first. Pay only as an absolute last resort, after consulting a lawyer and your country's cyber crime authority.
Disconnect from the network and log out of cloud storage
Pull the Ethernet cable and turn off Wi-Fi on the affected PC. If multiple computers share the network, do the same on every machine you suspect could be affected, including any servers and NAS units.
Then sign out of cloud storage clients (OneDrive, Dropbox, Google Drive, iCloud) from their app settings. If you can, pause the sync. Some ransomware uses the running sync client to push encrypted versions over your clean cloud copies.
Modern ransomware spreads laterally across SMB shares, mapped drives, RDP, and reachable network neighbors. Disconnecting stops the spread the moment you do it. Logging out of cloud sync clients prevents the ransomware from encrypting the cloud copies of your files via the sync API.
Unplug external drives and USB storage
Safely eject any external drives, USB sticks, SD cards, and network-attached storage shares - then unplug them. If a drive was connected when the ransomware ran, the files on it may already be encrypted, but unplugging stops further damage.
Critically: don't reconnect any drive (including your most recent backup) to this PC until the ransomware is removed in Phase 3. Reconnecting an external backup to an actively-infected PC is the most common way that backup gets encrypted too.
Save the ransom note and a sample encrypted file
Copy the ransom note and one small encrypted file (under 1 MB) to a USB stick, or photograph the note with your phone. You'll need both for the variant identification step.
The ransom note is usually one of:
- A
.txtfile in every encrypted folder (typicallyHOW_TO_DECRYPT.txt,README.txt, or_readme.txt) - An
.htmlfile with the same purpose - A changed desktop wallpaper - photograph it
- A lock-screen interrupt that runs at startup - rarer
Don't delete the note. Variant identification depends on its exact wording, the contact email, and the bitcoin wallet address. The note is also evidence if you report to authorities.
Identify the variant with ID Ransomware
From a clean device (your phone is fine, or another PC that wasn't on the affected network), visit id-ransomware.malwarehunterteam.com. Upload the ransom note and the sample encrypted file. The site identifies the variant family and tells you whether a free decryptor exists.
ID Ransomware is run by the Malware Hunter Team. Files you upload are kept private - they're used for analysis, not published. If you're concerned about uploading data anyway, you can paste the contact email and bitcoin wallet from the note - those are often enough for identification.
The ransomware itself must be removed before any file recovery. If it's still active, anything you restore in Phase 4 gets re-encrypted within minutes.
Boot to Safe Mode with Networking and download the scanners
Safe Mode loads only the minimal Windows drivers, which prevents most ransomware from auto-running while you set up the scanners.
Windows 11: open , click Restart now next to Advanced startup. After the restart, click , then press 5 or F5.
Windows 10: click the Windows logo, hold Shift, click the Power icon and choose Restart. From the Choose-an-option screen, click , then press F5.
Once Safe Mode has loaded, turn Wi-Fi back on and download Combo Cleaner (used in step 8) and Microsoft Safety Scanner (used in step 9). Save both installers to your Desktop, then disconnect Wi-Fi again before scanning.
Run Microsoft Defender Offline
Reboot to normal Windows. Open . Select Microsoft Defender Antivirus (offline scan) and click Scan now. The PC restarts into a stripped-down environment and scans the disk before Windows fully loads.
Some ransomware variants drop bootkit components or kernel hooks that hide from any scanner running on the same Windows session that's already infected. A pre-boot offline scan sees the disk before the malware can load itself.
VB100 certified. Includes anti-trojan, registry/persistence scanning, and anti-spyware in one pass. The 7-day free trial is available.
Download Combo CleanerRun a full Combo Cleaner scan
Run the installer you downloaded in step 6 and start a full system scan (not the quick scan). Let it complete, review what it detected, and apply the recommended actions. Combo Cleaner quarantines the ransomware executable and the registry / scheduled-task entries that re-launch it on reboot.
Run Microsoft Safety Scanner and re-enable Defender
Run Microsoft Safety Scanner (MSERT.exe) as a second-opinion full scan. The binary expires every 10 days so the copy you downloaded has the latest signatures.
Once it finishes, open and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all on. Many ransomware variants disable Defender during the attack - this is where you switch it back on so the next attempt can't repeat the trick.
Different scanning engines catch different threats. Running an additional Microsoft scan after Combo Cleaner is the most underused verification step in malware removal - and free.
Try the steps in order. The first decryptor that works ends the recovery process - no need to do all four.
Check the No More Ransom Project for a free decryptor
Visit nomoreransom.org and search the Decryption Tools list for the variant name returned by ID Ransomware. The project is run by Europol, the Dutch Police, and security vendors - everything listed is legitimate and free.
If a decryptor exists, download it onto a clean PC, copy it across, and follow its instructions exactly. Decryptors usually want you to point them at a sample encrypted file plus its known unencrypted version (sometimes any image you previously had a backup of works).
Free decryptors exist for parts of the STOP/Djvu, GandCrab, REvil, Avaddon, Conti and Hive families, among others. Most modern variants don't have public decryptors - if yours isn't listed, that's expected; move to the next step.
Try Windows Volume Shadow Copies
Windows automatically creates Volume Shadow Copies of files when System Restore points are made or scheduled backups run. Most ransomware tries to wipe these (vssadmin delete shadows /all /quiet), but the deletion sometimes fails partially - especially if the running user doesn't have full admin rights. When it does fail, snapshots survive that contain pre-encryption versions of your files.
First, check what's there. Open Command Prompt as Administrator and run:
vssadmin list shadows
If you see entries listed, shadow copies survived. To restore from them:
- Built-in: right-click any folder → Properties → Previous Versions tab. Pick a snapshot dated before the infection and restore.
- Better tool for browsing: install Shadow Explorer (free). It shows all snapshots as a normal file tree and lets you copy out only the files you want.
Shadow Copies recover the original files exactly, with no risk of decryption errors. If they survived, this is faster and cleaner than running a decryptor on the encrypted set.
Restore from cloud or external backup
If you have a backup that pre-dates the infection, this is the cleanest recovery available. Important precautions:
- Don't reconnect a backup drive until Phase 3 is complete. If the ransomware is still active, plugging in the backup encrypts it too.
- For cloud backups (OneDrive, Dropbox, Google Drive, iCloud), use the Version History feature to roll individual files back to pre-encryption versions.
- OneDrive specifically has a "Restore your OneDrive" feature: if it detected mass file changes, you can roll back the entire account up to 30 days. Sign in at OneDrive on the web, click the Settings gear, and choose Restore your OneDrive. Microsoft 365 subscribers also get ransomware detection alerts; non-subscribers get one free recovery.
- Verify the restored files open correctly before you delete the encrypted set. Test a few documents, photos, and any database / project files.
Try Recuva as a last-resort recovery
Recuva is a long shot, not a primary recovery tool. Most modern ransomware encrypts files in place - it reads the original, encrypts the data, and writes the encrypted bytes back to the same disk location. In that case, the original isn't deleted, just rewritten - and Recuva has nothing to find.
But for older or simpler variants that deleted originals before creating encrypted copies (rather than encrypting in place), Recuva can sometimes pull the originals from unallocated disk space. Worth trying as a last resort, especially before you use the disk much further.
If you try it:
- Stop using the disk as much as possible - every disk write reduces recovery odds
- Run Recuva from a USB stick, not from the affected disk
- Use Deep Scan mode (slower but the only mode worth running for this scenario)
Don't skip the steps above expecting Recuva to bail you out. It works in maybe 5-20% of cases, depending on the variant and how soon you try.
Report the attack to authorities
Even if your files aren't recovered, your report helps authorities track variants, attribute groups, and warn future victims. In some jurisdictions (especially the US and UK) early reporting can sometimes help recall a wired ransom payment via banking partners.
Save the report number - banks, insurers, and credit bureaus will ask for it. If you operate a business, you may also have legal disclosure obligations (GDPR in the EU, state breach laws in the US) that run on a 72-hour clock.
Plan 3-2-1 backups going forward
The single best defense against ransomware is a tested backup. Use the 3-2-1 rule:
- 3 copies of your data
- 2 different storage media (e.g., internal drive + external drive)
- 1 offline / air-gapped copy (an external drive that isn't always connected)
Recommended cadence:
- Daily: cloud sync (OneDrive, Dropbox, Google Drive) - convenient, but vulnerable if the ransomware reaches the sync folder. The Version History feature is what saves you
- Weekly: external drive that you connect briefly, then disconnect - the air-gap is what protects against ransomware
- Monthly: a second external drive stored off-site (different physical location) - protects against fire, theft, flood
Test the backup at least once. Open a few files from it, check sizes match, restore one to a different folder. An untested backup isn't a backup - it's a hope.
Patch the entry point and monitor for 30 days
Most reinfections happen via the same vector that worked the first time. Until you've patched the entry point, watch for:
- Unusual disk activity, unexpected file modifications, or unfamiliar processes in Task Manager
- Unexpected reboots or new accounts you didn't create
- Defender or your antivirus turning itself off again
Common entry vectors and what to do about each:
- Phishing email with a malicious attachment - review email filters and train yourself / staff to recognise the patterns - see pcrisk's Phishing/Scam reference
- Exposed RDP with weak passwords - disable Remote Desktop from if you don't need it. If you do, put it behind a VPN and require a long password plus MFA
- Unpatched VPN appliances or public-facing apps - check the vendor's advisories page and apply the latest firmware
- Cracked / pirated software - was the most common vector for STOP/Djvu in particular. Don't run software from torrent sites
Run a Combo Cleaner scan weekly for the first month. Update Windows, browsers, and applications aggressively.
Important: Removing a ransomware infection requires a full system scan, not a manual file delete. If you're not confident with the manual procedure, run an automated scan with Combo Cleaner and Windows Defender and stop there - that combination removes the vast majority of consumer ransomware variants. Then move to Phase 4 for file recovery, or to Phase 5 if your files are unrecoverable and you need to start fresh from a clean Windows install.
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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.
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