*[email protected]*.nuclear

[Content by Gemini 2.5]

This detailed resource aims to provide comprehensive information regarding the ransomware variant identified by the file extension *[email protected]*.nuclear. Understanding its characteristics and implementing robust countermeasures are crucial for effective protection and recovery.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware encrypts files and appends a multi-part extension, typically in the format:
    .[ID].[[email protected]].nuclear
    Where [ID] is a unique hexadecimal identifier generated for the victim or session.
    For example, a file named document.docx might become [email protected].

  • Renaming Convention: The renaming convention follows a pattern consistent with variants of the STOP/Djvu ransomware family. It involves:

    1. Appending a unique ID (8-10 hexadecimal characters) to the original filename.
    2. Subsequently appending the attacker’s contact email, which in this case is [email protected].
    3. Finally, appending the primary static extension .nuclear.
      This pattern ensures that the victim is immediately aware of the encryption and the contact method provided by the attackers.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While the [email protected] extension is a specific variant identifier, the underlying ransomware family (STOP/Djvu) has been highly active since late 2017/early 2018. New extensions and contact emails are frequently released by the threat actors. Variants with the [email protected] email as part of the extension likely emerged in late 2023 to early 2024, fitting the typical refresh cycle for Djvu strains. Specific public reports on this exact string might be limited due to the rapid iteration of these variants, but its characteristics align perfectly with the established Djvu modus operandi.

3. Primary Attack Vectors

The *[email protected]*.nuclear ransomware, like most STOP/Djvu variants, primarily leverages social engineering and deceptive distribution methods:

  • Software Cracks & Pirated Content: This is the most prevalent vector. Users seeking free or cracked versions of paid software (e.g., Adobe products, Microsoft Office, video games), key generators, or activators often download installers bundled with the ransomware from untrusted websites, torrents, or file-sharing platforms.
  • Fake Software Updates: Malicious websites or pop-ups may trick users into downloading “critical updates” for browsers (e.g., Chrome, Firefox) or other legitimate software, which are, in fact, ransomware installers.
  • Phishing Campaigns: While less common for Djvu compared to more targeted ransomware groups, basic phishing emails containing malicious attachments (e.g., seemingly legitimate documents with embedded macros, or archives containing executables) or links to compromised websites can serve as an entry point.
  • Malvertising & Drive-by Downloads: Users visiting compromised or malicious advertising networks might be redirected to sites that automatically download the ransomware or exploit browser vulnerabilities to initiate a download (though less frequent for Djvu).
  • Remote Desktop Protocol (RDP) Exploits: While not a primary method for initial infection with Djvu, poorly secured RDP endpoints can be brute-forced or exploited, allowing attackers to manually deploy the ransomware once access is gained. This is more common in corporate environments.
  • Bundling with Freeware: Less reputable freeware or shareware download sites sometimes bundle unwanted programs, including ransomware, with legitimate software.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against *[email protected]*.nuclear and similar threats:

  • Regular, Offline 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 offsite or offline. This is the single most important defense against data loss from ransomware.
  • Software Updates & Patching: Keep your operating system (Windows, macOS, Linux), web browsers, antivirus software, and all installed applications fully updated. Patches often fix security vulnerabilities that ransomware might exploit.
  • Reputable Antivirus/Endpoint Detection and Response (EDR): Use a high-quality antivirus solution with real-time protection and behavioral analysis capabilities. Ensure it is updated daily. For organizations, EDR solutions offer more advanced threat detection and response.
  • Email Security: Implement spam filters and be extremely cautious of unsolicited emails, especially those with attachments or links. Verify the sender before opening anything.
  • User Education: Train users to recognize phishing attempts, identify suspicious links, and avoid downloading content from unofficial or pirated sources.
  • Strong Passwords & Multi-Factor Authentication (MFA): Use complex, unique passwords for all accounts and enable MFA wherever possible, especially for RDP and cloud services.
  • Disable/Secure RDP: If RDP is not essential, disable it. If required, secure it with strong passwords, MFA, network level authentication (NLA), and restrict access to trusted IPs only.
  • Network Segmentation: Segment networks to limit lateral movement of ransomware in case of a breach, preventing it from spreading across the entire infrastructure.

2. Removal

Once an infection is detected, immediate action is crucial to contain and remove the ransomware:

  • Isolate Infected Systems: Disconnect the infected computer(s) from the network (unplug Ethernet, disable Wi-Fi) immediately to prevent further spread to other devices or network shares.
  • Identify Ransomware Processes: Boot the system into Safe Mode with Networking (if possible) or use a clean bootable antivirus rescue disk. Use Task Manager or Process Explorer to identify and terminate suspicious processes.
  • Scan with Reputable Anti-Malware: Perform a full system scan using an updated, reputable antivirus or anti-malware solution. Consider using multiple scanners (e.g., Malwarebytes, HitmanPro) to ensure thorough detection.
  • Remove Persistence Mechanisms: Check common persistence locations for malicious entries:
    • Registry Editor (regedit.exe): HKEYCURRENTUSER\Software\Microsoft\Windows\CurrentVersion\Run, HKEYLOCALMACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • Task Scheduler (taskschd.msc): Look for newly created, suspicious scheduled tasks.
    • Startup Folder: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp and user-specific startup folders.
    • Host File Modification: Check C:\Windows\System32\drivers\etc\hosts for entries redirecting security websites to 127.0.0.1 (localhost). Remove any such entries.
  • Delete Ransomware Files: Once identified, delete all associated ransomware files (executables, ransom notes like _readme.txt).
  • Check for Additional Malware: Djvu variants often drop additional malware, such as information stealers (e.g., Vidar, Azorult, RedLine Stealer). Perform thorough scans to detect and remove these secondary infections.

3. File Decryption & Recovery

  • Recovery Feasibility: For *[email protected]*.nuclear (a STOP/Djvu variant), decryption feasibility largely depends on whether an online key or an offline key was used during encryption.
    • Online Key: If the ransomware successfully connected to its command-and-control (C2) server, it uses a unique, online-generated key for encryption. Decryption in this scenario is generally impossible without the attacker’s private key. Paying the ransom is not recommended as there’s no guarantee of decryption, and it fuels future attacks.
    • Offline Key: If the ransomware failed to connect to its C2 server, it might resort to using a static, pre-defined “offline” key. In such cases, if this specific offline key is recovered or brute-forced by security researchers, decryption tools might become available.
    • Checking for Offline Key: The ransom note or diagnostic tools (like STOPDecrypter from Emsisoft) can sometimes indicate if an online or offline key was used.
  • Methods/Tools Available:
    • Emsisoft Decryptor for STOP Djvu: This is the primary tool for decrypting files encrypted by STOP/Djvu variants. It is constantly updated by Emsisoft as new offline keys are discovered. You can download it from the Emsisoft website. It requires one original, unencrypted file (if available) and one encrypted file pair to potentially identify the key.
    • System Restore & Shadow Volume Copies (VSS): *[email protected]*.nuclear and other Djvu variants are known to delete Shadow Volume Copies to prevent recovery. However, it’s always worth checking if any VSS snapshots survived (vssadmin delete shadows /all /quiet is often executed by the malware).
    • Data Recovery Software: In some cases, ransomware might delete original files after encryption rather than overwriting them directly. Data recovery software (e.g., PhotoRec, Recuva) might be able to recover some original files, especially if the infection was recent and the disk hasn’t been heavily used since.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP Djvu: Crucial for attempted decryption.
    • Updated Antivirus/Anti-malware: For removal and prevention.
    • Windows Updates: Ensure the system is fully patched against known vulnerabilities.
    • Backup Solutions: Essential for actual data recovery.

4. Other Critical Information

  • Additional Precautions:

    • Ransom Note: The ransomware typically drops a text file named _readme.txt (or similar) in every folder containing encrypted files and on the desktop. This note contains instructions for payment and contact information (the [email protected] email).
    • Host File Modification: Djvu variants frequently modify the Windows hosts file to block access to legitimate security websites (e.g., antivirus vendor sites, tech forums) to hinder victims from seeking help or downloading security tools. Always check and clean the hosts file after an infection.
    • Information Stealers: As mentioned, this ransomware family frequently bundles with information-stealing malware (e.g., Vidar, Azorult, RedLine Stealer). Assume your credentials, cryptocurrency wallets, browser data, and other sensitive information might have been compromised. Change all important passwords immediately from a clean system.
    • Fake Decryptors: Be extremely wary of “decryption tools” offered by unverified sources. Many are fake and can contain additional malware or cause further damage. Stick to reputable sources like Emsisoft or No More Ransom.

  • Broader Impact:

    • Target Audience: *[email protected]*.nuclear primarily targets individual users and small to medium-sized businesses due to its reliance on less sophisticated, high-volume attack vectors (pirated software, phishing).
    • Economic Impact: The widespread nature of Djvu ransomware variants leads to significant financial losses for victims, both from potential ransom payments (if made) and the cost of data recovery, system cleanup, and downtime.
    • Psychological Impact: Victims often experience significant stress and frustration due to the loss of irreplaceable personal files or critical business data.
    • Evolution: The rapid iteration of Djvu variants, constantly changing file extensions and contact emails, makes it challenging for security researchers to provide immediate decryption solutions for every new strain. This continuous evolution keeps the threat persistent and effective.

By understanding these technical details and implementing the recommended recovery strategies, individuals and organizations can significantly improve their resilience against the *[email protected]*.nuclear ransomware variant and similar threats.