Remove STOP/DJVU Ransomware and Recover .djvu Files

Symptoms

All your personal files (documents, photos, databases) have a .djvu extension added. A ransom note named _readme.txt appears in each folder, demanding payment for decryption. System performance may degrade, and you cannot open your files.

Root Causes

STOP/DJVU ransomware is typically spread through cracked software, fake downloads, malicious email attachments, or exploit kits. Once executed, it encrypts files using a strong AES-256 algorithm and appends the .djvu extension. It also deletes Volume Shadow Copies to prevent recovery.

Step-by-Step Fix

Step 1: Isolate the Infected System

1. Disconnect from the internet immediately to prevent communication with command servers.
2. Unplug any external drives or network shares that may be affected.

Step 2: Remove the Ransomware

1. Boot into Safe Mode with Networking: Restart your PC and press F8 (or Shift + Restart in Windows 10/11) and select Safe Mode with Networking.
2. Download and run a reputable anti-malware tool like Malwarebytes or Kaspersky Virus Removal Tool.
3. Perform a full system scan and remove all detected threats.
4. Alternatively, use Windows Defender Offline Scan from the recovery environment.

Step 3: Attempt File Recovery

Option A: Restore from Backup

1. If you have a clean backup (external drive, cloud), restore files after ensuring the ransomware is removed.
2. Do not connect the backup until the system is clean.

Option B: Use the Emsisoft Decryptor

1. Visit the official Emsisoft STOP DJVU Decryptor page.
2. Download the tool and run it as Administrator.
3. Select the encrypted files (usually located in C:\Users\[Username]\).
4. Click Decrypt. The tool will attempt to recover files using known keys.
5. If decryption fails, the ransomware may be using an online key (not yet recovered). Wait for updates.

Option C: Use Shadow Volume Copies (if not deleted)

1. Right-click the encrypted file, select Properties > Previous Versions.
2. If a previous version exists, copy and restore it.

Option D: Data Recovery Software

1. Use tools like Recuva or PhotoRec to recover deleted original files (before encryption).
2. Scan the drive and recover files to a separate location.

Alternative Fixes

• System Restore: If System Restore points exist, revert your PC to a date before infection.
• Reset Windows: As a last resort, perform a clean install of Windows (backup personal data first, but note that encrypted files will remain encrypted).

Prevention

• Always keep your operating system and software updated.
• Use a reputable antivirus with real-time protection.
• Never download cracked software or open suspicious email attachments.
• Enable File History or maintain regular backups to an external drive or cloud service.
• Disable macros in Office documents.
• Use a standard user account instead of an administrator account for daily tasks.

Important Notes

• Do not pay the ransom. There is no guarantee you will get your files back, and it encourages criminal activity.
• Some variants of STOP/DJVU use an offline key that can be decrypted by tools like Emsisoft Decryptor. Check the tool's website for updates.
• If you have an online key (unique ID), decryption may be impossible without the attacker's key.

Technical Details

For further assistance, visit the official Emsisoft support page or the NoMoreRansom project.