*[email protected]*.eth

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This document provides a comprehensive overview of the ransomware variant identified by the file extension *[email protected]*.eth. Based on the file extension pattern, this variant is strongly suspected to be part of the prolific STOP/Djvu ransomware family, which frequently changes its appended extensions and contact email addresses.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware is [email protected].
  • Renaming Convention: When a file is encrypted, the ransomware appends this full string to the original filename.
    • Example: A file named document.docx would be renamed to [email protected].
    • The ransomware also typically drops a ransom note, often named _readme.txt, in every folder containing encrypted files. This note contains instructions for decryption, usually demanding payment in cryptocurrency and directing victims to the specified email address ([email protected]).

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While a precise start date for the specific [email protected] variant is difficult to pinpoint without specific threat intelligence logs, it is part of the broader STOP/Djvu ransomware family, which has been continuously active and evolving since late 2017/early 2018. New variants with different extensions are released frequently, often daily. Therefore, this variant would have emerged as part of an ongoing campaign within the last several months to a year, maintaining the consistent distribution methods of its predecessors.

3. Primary Attack Vectors

The *[email protected]*.eth variant, like other STOP/Djvu strains, primarily relies on less sophisticated but highly effective distribution methods, targeting individual users and small businesses rather than large enterprises.

  • Software Cracks/Pirated Software: This is the most common vector. Victims often download seemingly legitimate cracks, keygens, pirated games, or licensed software from untrusted websites. These downloads are often bundled with the ransomware executable.
  • Malicious Downloads & Drive-by Downloads: Visiting compromised websites, clicking on malicious advertisements, or downloading files from dubious sources can lead to infection.
  • Fake Software Updates: Pop-ups or emails prompting users to install critical updates for popular software (e.g., Flash Player, Java, web browsers) can deliver the ransomware.
  • Phishing Campaigns: While less common than software cracks for Djvu, email attachments (e.g., seemingly legitimate invoices, shipping notifications, or resumes) containing malicious scripts or documents can also serve as an infection vector.
  • Remote Desktop Protocol (RDP) Exploits: In some cases, weak RDP credentials can be brute-forced, allowing attackers to gain access to a system and manually deploy the ransomware. This is more common for targeted attacks on small businesses.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against *[email protected]*.eth and similar ransomware.

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy: at least three copies of your data, stored on two different media types, with one copy off-site or offline. This is the ultimate recovery solution.
  • Use Reputable Antivirus/Anti-Malware Software: Keep your security software updated and perform regular scans. Enable real-time protection.
  • Operating System & Software Updates: Keep your OS (Windows, macOS, Linux) and all applications (browsers, plugins, productivity suites) fully patched. Many ransomware variants exploit known vulnerabilities.
  • Be Skeptical of Downloads: Avoid downloading cracked software, pirated content, or files from untrusted websites. Always verify the source before downloading anything.
  • Email Vigilance: Be cautious of unsolicited emails, especially those with attachments or links. Verify the sender and content before opening.
  • Disable/Harden RDP: If RDP is necessary, ensure strong, unique passwords are used, implement multi-factor authentication (MFA), and restrict access to trusted IP addresses where possible.
  • User Account Control (UAC): Do not disable UAC on Windows, as it helps prevent unauthorized changes to your system.
  • Ad Blocker: Using a reputable ad blocker can prevent malicious ads (malvertising) from serving ransomware.

2. Removal

Once an infection is detected, immediate action is crucial to prevent further spread and prepare for recovery.

  • Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet cable, disable Wi-Fi). This prevents the ransomware from spreading to other devices on the network.
  • Identify the Ransomware: Look for the ransom note (_readme.txt) and the changed file extensions to confirm it’s *[email protected]*.eth.
  • Boot into Safe Mode: Restart the computer and boot into Safe Mode with Networking. This often prevents the ransomware process from fully launching and allows security tools to run effectively.
  • Run a Full System Scan: Use a reputable, updated anti-malware solution (e.g., Malwarebytes, ESET, Windows Defender, Sophos) to perform a deep scan. Allow the software to quarantine or remove detected threats.
  • Check for Persistence: Examine common persistence locations (e.g., Registry Run keys, Startup folders, Task Scheduler) for any suspicious entries related to the ransomware. Manually remove them if found. Tools like Autoruns from Sysinternals can assist here.
  • Delete Ransom Note: Once the ransomware executable is removed, delete all instances of the _readme.txt ransom note.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • STOP/Djvu Decryption Status: Decryption feasibility for STOP/Djvu variants (including *[email protected]*.eth) heavily depends on whether an online or offline encryption key was used.
      • Online Keys: Most common. If the victim’s computer connected to the attacker’s command-and-control (C2) server during encryption, a unique “online” key is generated for that specific victim. Currently, there is no public tool to decrypt files encrypted with an online key. The only way would be if the attackers publish the keys or if law enforcement seizes their servers and releases the keys (which is rare).
      • Offline Keys: Less common. If the ransomware failed to connect to the C2 server (e.g., no internet connection during encryption, or C2 server was down), it uses a hardcoded “offline” key. Files encrypted with offline keys can often be decrypted if the specific offline key is known or has been recovered.
    • How to Check Key Type: The PersonalID found in the _readme.txt ransom note and/or the C:\SystemID\PersonalID.txt file (often created by the ransomware) can indicate the key type. If the PersonalID ends with t1 or t3 (or other specific patterns identified by security researchers), it’s likely an offline key.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/Djvu: This is the primary and most reliable tool for attempting decryption of STOP/Djvu variants. It is developed in cooperation with anti-malware researchers and law enforcement.
      • Usage: Download the Emsisoft Decryptor. It will attempt to match your encrypted files with known keys. For offline keys, it often succeeds. For online keys, it will inform you that decryption is not possible with current knowledge.
      • Availability: Freely available from Emsisoft’s website or the No More Ransom! project website.
    • Data Recovery Software: Even if direct decryption isn’t possible, try data recovery tools (e.g., PhotoRec, R-Studio, EaseUS Data Recovery Wizard) to recover older, unencrypted versions of files or deleted shadow copies (though Djvu often attempts to delete these).
    • Shadow Explorer: A tool to check for and restore previous versions of files from Volume Shadow Copies, though as mentioned, Djvu often deletes these using vssadmin.exe Delete Shadows /All /Quiet.

4. Other Critical Information

  • Additional Precautions:
    • Do NOT Pay the Ransom: There is no guarantee that paying the ransom will result in decryption. You are dealing with criminals, and they may simply take your money and disappear. Moreover, paying funds their operations, perpetuating the cycle of attacks.
    • Maintain System Integrity: After removal, consider a clean reinstallation of your operating system if you’re unsure about the thoroughness of the cleanup.
    • Password Reset: Change all system passwords and any online service passwords that might have been stored or cached on the compromised machine.
    • Inform Authorities: Report the incident to your local law enforcement agency or cybersecurity authorities (e.g., IC3 in the US, National Cyber Security Centre in the UK).
  • Broader Impact:
    • Widespread Consumer Impact: STOP/Djvu ransomware, due to its low-sophistication distribution methods (cracked software, fake installers), has a disproportionately large impact on individual users and small businesses who may lack robust cybersecurity defenses and backup strategies.
    • Evolving Threat: The continuous release of new variants with minor changes (like the extension) means that detection signatures and decryption efforts are in a constant race against the attackers.
    • Data Loss and Financial Strain: Victims often face significant data loss if they don’t have backups and cannot decrypt their files. The cost of recovery (time, professional services, potential ransom payment) can be substantial.
    • Threat to Digital Trust: The use of compromised software and fake updates erodes trust in digital content and software distribution channels.