@cock.email

[Content by Gemini 2.5]

The ransomware variant identified by the file extension @cock.email is a malicious program designed to encrypt files on infected systems, rendering them inaccessible. This specific file extension pattern, particularly the inclusion of an email address, is commonly observed in variants of the STOP/Djvu ransomware family, a prolific and frequently updated threat. While the core functionality aligns with other ransomware, its specific characteristics warrant a detailed breakdown for effective combat and recovery.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware variant is generally appended as .ID-[random string].[email address], with the given pattern specifically being @cock.email.
  • Renaming Convention: The ransomware typically appends the @cock.email extension to the original filename. Before the @cock.email part, it often includes a unique victim ID, which can sometimes be crucial for decryption attempts. For example, a file named document.pdf might become document.pdf.id[unique_alphanumeric_string][email protected]. It may also drop a ransom note, typically named _readme.txt, in every folder containing encrypted files.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While the id[uniqueID][email protected] extension itself might be a newer or less documented variant/campaign, the underlying STOP/Djvu ransomware family from which it likely originates has been highly active since late 2017/early 2018. New variants with slightly altered extensions, like @cock.email, emerge frequently, often on a daily or weekly basis, making it challenging to pinpoint the exact first appearance of this specific extension pattern. However, it represents a continuation of an ongoing, widespread threat.

3. Primary Attack Vectors

  • Propagation Mechanisms: STOP/Djvu variants, including those using the @cock.email extension, primarily rely on social engineering and deceptive tactics for propagation rather than exploiting complex network vulnerabilities.
    • Bundled Software/Cracked Software: This is the most prevalent vector. The ransomware is often distributed by bundling it with pirated software, cracked versions of legitimate programs, key generators (keygens), software activators, and other illicit downloads found on torrent sites, file-sharing platforms, and shady download portals. Users seeking free software unwittingly download and execute the ransomware.
    • Malvertising & Drive-by Downloads: Less common but still possible, the ransomware can be delivered via deceptive advertisements on malicious websites or through drive-by downloads where simply visiting a compromised site triggers the download.
    • Phishing Campaigns: While less common for STOP/Djvu compared to enterprise-targeted ransomware, basic phishing emails containing malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links to compromised websites can also serve as an infection vector.
    • Fake Software Updates: Pop-ups or notifications prompting users to install “critical updates” for browsers or other software can lead to the download of the ransomware.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Regular Data Backups: Implement a robust backup strategy following the 3-2-1 rule (3 copies, 2 different media types, 1 offsite/cloud). Ensure backups are isolated from the network to prevent encryption. This is the single most important defense against data loss.
    • Software & OS Patching: Keep your operating system, applications (especially web browsers, office suites, and security software), and firmware up to date with the latest security patches to close known vulnerabilities.
    • Antivirus/Endpoint Detection & Response (EDR): Deploy and maintain reputable antivirus or EDR solutions with real-time protection. Ensure definitions are updated frequently.
    • Strong Password Policies & MFA: Use strong, unique passwords for all accounts and enable Multi-Factor Authentication (MFA) wherever possible to protect against credential-based attacks, especially for RDP and VPN access.
    • Network Segmentation: Isolate critical systems and sensitive data from less secure parts of the network to limit lateral movement in case of a breach.
    • User Education: Train users about phishing, social engineering tactics, and the dangers of downloading software from unofficial or untrusted sources. Emphasize caution when clicking links or opening attachments from unknown senders.
    • Disable Unnecessary Services: Turn off services like SMBv1, PowerShell remoting, and RDP if not strictly needed, or secure them with strong access controls and VPNs.
    • Application Whitelisting: Implement application whitelisting to prevent unauthorized executables from running.
    • Principle of Least Privilege: Grant users and applications only the minimum necessary permissions to perform their tasks.

2. Removal

  • Infection Cleanup:
    1. Isolate the Infected System: Immediately disconnect the infected computer from the network (unplug Ethernet, turn off Wi-Fi) to prevent further spread to other devices.
    2. Identify the Ransomware Process: Use Task Manager (Windows) or Activity Monitor (macOS) to identify unusual or high-resource-consuming processes. Look for suspicious executables.
    3. Boot into Safe Mode: Restart the computer in Safe Mode (with Networking, if necessary, for updates) to prevent the ransomware from running automatically.
    4. Run a Full System Scan: Use a reputable, updated antivirus/anti-malware program (e.g., Malwarebytes, Windows Defender, Emsisoft Anti-Malware) to perform a deep scan and remove the ransomware executable and any associated malicious files. Some ransomware can disable security software, so it may be necessary to use a bootable antivirus scanner or a different system.
    5. Remove Persistence Mechanisms: Check common persistence locations like startup folders, registry run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\Software\Microsoft\Windows\CurrentVersion\Run), and Scheduled Tasks for entries related to the ransomware. Remove any found.
    6. Delete Ransomware Files and Notes: Once the active threat is removed, delete all encrypted files (only if you have viable backups or a decryptor is available) and the ransom notes (_readme.txt).
    7. Patch and Secure: Ensure all software and the operating system are fully updated. Review system logs for signs of how the initial infection occurred and address any vulnerabilities.

3. File Decryption & Recovery

  • Recovery Feasibility:

    • Direct Decryption: For many STOP/Djvu variants, including those with extensions like @cock.email, decryption may be possible, but it is not guaranteed and depends on several factors.
      • Online vs. Offline Keys: STOP/Djvu variants use either “online keys” (unique for each infection, requiring the attackers’ server to decrypt) or “offline keys” (generic keys used when the malware cannot contact its command and control server). Offline keys are often recoverable by researchers.
      • No More Ransom Project: The No More Ransom project (a joint initiative by law enforcement and IT security companies) often provides free decryptors for STOP/Djvu variants. Emsisoft is a key contributor and frequently updates its STOP/Djvu decryptor.
      • How to Use No More Ransom/Emsisoft Decryptor: You typically need to upload an encrypted file and the ransom note (_readme.txt) to the No More Ransom Crypto Sheriff tool. If a decryptor exists, it will point you to it. The Emsisoft decryptor usually requires at least one encrypted file (preferably a small one) and the ransom note to attempt to identify the correct key.
    • Recovery Methods (if decryption is not possible):
      • From Backups: The most reliable method. Restore your files from clean, uninfected backups created before the infection.
      • Shadow Volume Copies (VSS): Windows creates “Shadow Copies” (System Restore Points). The ransomware often attempts to delete these, but sometimes it fails. You can try recovering previous versions of files or folders using Windows’ built-in “Restore previous versions” feature or tools like ShadowExplorer.
      • Data Recovery Software: In some cases, if the original files were simply overwritten or deleted before encryption, data recovery software might be able to retrieve fragments of the original files, though success is often limited and the recovered files may be corrupted.

  • Essential Tools/Patches:

    • Emsisoft Decryptor for STOP Djvu: Crucial tool for decryption attempts. Download only from reputable sources like Emsisoft’s official website or No More Ransom.
    • Malwarebytes, Windows Defender, or ESET: For malware detection and removal.
    • ShadowExplorer: For attempting to recover files from Shadow Volume Copies.
    • Microsoft Windows Updates: Ensure the OS is fully patched.
    • Browser Updates: Keep web browsers (Chrome, Firefox, Edge) updated.
    • Adobe Flash/Reader/Java Updates: If these are installed, ensure they are updated or, preferably, uninstalled if not strictly necessary.

4. Other Critical Information

  • Additional Precautions:

    • Do NOT Pay the Ransom: Paying the ransom encourages attackers, provides no guarantee of decryption, and fuels future ransomware development. Focus on recovery through backups or decryptors.
    • Documentation: Document everything: the exact file extension, the ransom note content, the unique ID (if any), and the date of infection. This information is vital for law enforcement and security researchers.
    • Professional Help: If critical data is encrypted and self-recovery methods fail, consider consulting with professional data recovery specialists or incident response firms. Be wary of unverified “decryption services” that may be scams.
    • Check for Information Stealers: Many STOP/Djvu variants are known to also install information-stealing malware (like Vidar, Azorult, or SmokeLoader) that can steal browser cookies, saved passwords, cryptocurrency wallet data, and other sensitive information. After removing the ransomware, change all critical passwords (especially for banking, email, and social media) from a clean, uninfected device.

  • Broader Impact:

    • High Volume Threat: The STOP/Djvu family, including its variants like @cock.email, represents one of the most widespread and consistently active ransomware threats, primarily impacting individual users and small businesses. Its constant evolution with new extensions makes it a persistent challenge for standard antivirus solutions to keep up.
    • Gateway to Other Threats: The common distribution method via cracked software makes it a significant risk not just for encryption, but also for silent installation of other malware, including info-stealers, which can lead to further financial fraud or identity theft.
    • Psychological Toll: Beyond data loss, victims often experience significant stress, financial strain, and loss of productivity, highlighting the profound personal and operational impact of such attacks.