*.*[email protected]*.com

[Content by Gemini 2.5]

This report details the ransomware variant identified by the file extension pattern *.*[email protected]*.com. Based on the distinctive file renaming convention that embeds a contact email address within the file extension, this ransomware is unequivocally a variant of the STOP/Djvu ransomware family (also commonly referred to as Djvu, .djvu, or STOP). The [email protected] component indicates the specific contact email chosen by the threat actors for this particular variant.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by this variant will append an extension that typically includes a victim ID, the specified email address, and often another specific variant extension. For instance, a file named document.docx might become document.docx.id[random_string][email protected]. The final .com is likely the specific variant extension for this particular strain.
  • Renaming Convention: The general pattern is:
    [original_filename].[original_extension].id[8-character_victim_ID].[contact_email_address].[variant_extension]
    Example: [email protected]
    Alongside encrypted files, a ransom note will be dropped in every folder containing encrypted data, typically named _readme.txt. This text file contains instructions on how to pay the ransom (usually in Bitcoin) and contact the attackers.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The STOP/Djvu ransomware family has been active since late 2018/early 2019 and continues to be one of the most prolific ransomware threats, constantly releasing new variants with different extensions and contact emails. The specific [email protected] variant would have emerged within this ongoing timeline, as the threat actors frequently change their contact details and extensions to evade detection and tracking. This specific variant likely appeared in late 2023 or early 2024, given the typical rotation of these extensions by the Djvu operators.

3. Primary Attack Vectors

The STOP/Djvu ransomware family, including this [email protected] variant, primarily relies on less sophisticated but highly effective propagation mechanisms:

  • Cracked Software & Illegitimate Downloads: This is the most prevalent method. Users download pirated software, keygens, software cracks, activators, or installers from untrustworthy websites, torrents, or file-sharing services. The ransomware is bundled within these seemingly legitimate downloads.
  • Malicious Websites & Drive-by Downloads: Visiting compromised or malicious websites can sometimes lead to an infection without explicit user interaction (though less common for Djvu than exploit kits).
  • Fake Software Updates: Pop-ups or alerts masquerading as legitimate software updates (e.g., for Flash Player, Java, web browsers) can trick users into downloading and executing the ransomware.
  • Malicious Advertisements (Malvertising): Clicking on deceptive advertisements on legitimate or illegitimate websites can redirect users to malicious sites or initiate downloads of the ransomware.
  • Email Phishing (Less Common but Possible): While less common than for enterprise-targeting ransomware, basic phishing emails with malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links could be used, particularly against less tech-savvy individuals.
  • Remote Desktop Protocol (RDP) Exploits (Less Common): Although Djvu primarily targets individuals and small businesses via consumer-grade attack vectors, poorly secured RDP endpoints can theoretically be exploited, though this is more characteristic of larger, more targeted ransomware operations.

Remediation & Recovery Strategies:

1. Prevention

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, 2 different media, 1 offsite). Ensure backups are immutable or offline to prevent ransomware from encrypting them.
  • Software Updates & Patching: Keep your operating system, web browsers, antivirus software, and all other applications fully updated. Threat actors often exploit known vulnerabilities to gain initial access.
  • Reliable Antivirus/Anti-Malware: Use a reputable cybersecurity suite with real-time protection and behavioral analysis capabilities. Keep its definitions up to date.
  • Email & Web Browsing Hygiene: Be extremely cautious with email attachments and links, especially from unknown senders. Avoid downloading software from unofficial or suspicious websites. Be wary of pop-up ads and unsolicited software update prompts.
  • Disable Unnecessary Services: Disable SMBv1 if not strictly required, and secure RDP access with strong passwords, multi-factor authentication (MFA), and network-level authentication (NLA).
  • User Account Control (UAC): Do not disable UAC, as it provides an additional layer of security by prompting for administrative privileges.

2. Removal

  • Isolate the Infected System: Immediately disconnect the infected computer from the network (both wired and Wi-Fi) to prevent the ransomware from spreading to other devices or network shares.
  • Identify the Ransomware Process: Use Task Manager (Windows) or Activity Monitor (macOS) to identify suspicious processes. Often, ransomware executables might have random names or mimic legitimate processes.
  • Scan with Reputable Anti-Malware: Boot the system into Safe Mode with Networking (if possible) or use a bootable anti-malware rescue disk (e.g., from Avast, Kaspersky, Bitdefender) to perform a full system scan. This helps remove the ransomware executable and any associated malicious files (such as information stealer modules often bundled with Djvu variants).
  • Check for Persistent Mechanisms: Examine startup folders, scheduled tasks, and registry entries for any persistence mechanisms left by the ransomware. Reputable anti-malware tools should handle this automatically.
  • Change All Passwords: After confirming the system is clean, change all passwords, especially for online accounts, as Djvu variants are often bundled with information stealers (e.g., RedLine Stealer, Vidar Stealer, SmokeLoader) that could compromise credentials.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • NO GUARANTEE OF DECRYPTION: The feasibility of decrypting files encrypted by this [email protected] variant largely depends on whether the ransomware used an “online” or “offline” encryption key.
      • Online Key: If an “online” key was used (meaning the ransomware successfully communicated with its command-and-control server to obtain a unique encryption key for your system), decryption is currently not possible without paying the ransom and receiving the private key from the attackers, which is strongly discouraged. Paying incentivizes further attacks and does not guarantee recovery.
      • Offline Key: If an “offline” key was used (meaning the ransomware failed to communicate with its C2 server and resorted to a hardcoded, static key), there is a chance of decryption. Security researchers often manage to recover these offline keys over time and integrate them into decryptor tools.
    • Emsisoft Decryptor: The most prominent and reliable tool for Djvu/STOP ransomware is the Emsisoft Decryptor for STOP/Djvu. This tool is constantly updated with new offline keys discovered by researchers.
      • How to Use: Download the Emsisoft Decryptor. It will attempt to identify the specific variant and test known keys. You will need at least one pair of an encrypted file and its original, unencrypted version (e.g., from a backup or another uninfected system) to help the decryptor identify the correct key.
      • Caution: The decryptor can only help if an “offline” key for your specific variant has been discovered and added to its database.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu: The primary tool for potential decryption.
    • Reputable Anti-Malware Software: (e.g., Malwarebytes, Avast, Bitdefender, Kaspersky) for removal.
    • Windows Updates: Ensure your operating system is fully patched.

4. Other Critical Information

  • Additional Precautions (Information Stealer Component): A significant characteristic of STOP/Djvu variants is their frequent bundling with an information-stealing malware (such as RedLine Stealer, Vidar Stealer, or other similar trojans). This means that even if you manage to decrypt your files, your sensitive data, browser cookies, cryptocurrency wallet information, and login credentials might have already been exfiltrated.
    • Immediate Action: Change all passwords for critical online accounts (email, banking, social media, cloud services) from an uninfected device after cleaning the system. Monitor financial accounts for suspicious activity.
  • Broader Impact:
    • Mass Market Distribution: Djvu variants target a wide range of individuals and small businesses due to their reliance on common attack vectors like pirated software. This makes them one of the most widespread ransomware families.
    • Continuous Evolution: The constant release of new variants with minor changes (new extensions, new contact emails) makes detection and decryption a continuous challenge for security researchers.
    • Psychological Impact: The personal nature of data loss and the direct communication via email can be highly distressing for victims.

Disclaimer: While significant effort is made to combat ransomware, paying the ransom is generally not recommended. It funds criminal enterprises and provides no guarantee of file recovery. Focus on prevention through robust backups and security practices.