*[email protected]*.insane

[Content by Gemini 2.5]

This document provides a comprehensive analysis and set of strategies to combat the ransomware variant identified by the file extension *[email protected]*.insane. This particular variant is a member of the extensive and continuously evolving STOP/Djvu ransomware family, which has caused widespread disruption globally.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware is [email protected]. This follows a typical pattern for STOP/Djvu variants, where the attacker’s contact email is embedded within the appended string.
  • Renaming Convention: The ransomware encrypts files and then modifies their names by appending the .[email_address].[extension] pattern. For example:

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While the [email protected] specific variant might have a more recent appearance, the parent STOP/Djvu ransomware family has been actively circulating since late 2017/early 2018. New variants, identified by different appended extensions or email addresses, are released almost daily, ensuring its continued relevance and ability to bypass signature-based detections. This particular variant likely emerged as part of the ongoing wave of Djvu attacks in late 2023 or early 2024.

3. Primary Attack Vectors

The *[email protected]*.insane variant, like other Djvu/STOP ransomware, primarily relies on social engineering and deceptive tactics:

  • Cracked Software/Pirated Content: This is the most prevalent vector. Users download and execute pirated software, key generators, software activators (e.g., KMS activators for Windows/Office), or torrents from untrustworthy sources. The ransomware executable is often bundled within these downloads.
  • Malicious Websites/Pop-ups: Drive-by downloads from compromised or malicious websites that mimic legitimate software download sites (e.g., fake Adobe Flash Player updates, fake installers for popular programs like Photoshop, Microsoft Office).
  • Phishing Campaigns: While less common for Djvu than for some enterprise-level ransomware, targeted phishing emails containing malicious attachments (e.g., seemingly legitimate documents with embedded macros) or links to malware download sites can also be used.
  • Malvertising: Deceptive advertisements on legitimate or illegitimate websites that redirect users to malicious download pages.
  • Remote Desktop Protocol (RDP) Exploitation (Less Common but Possible): If exposed RDP ports have weak credentials, the attackers might gain access and manually deploy the ransomware. However, this is more typical of larger ransomware operations.
  • Software Vulnerabilities (Rare for Djvu): Unlike some advanced ransomware (e.g., WannaCry exploiting EternalBlue), Djvu/STOP ransomware rarely exploits network-level vulnerabilities directly for propagation. Its primary mode is user-initiated execution.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against ransomware like *[email protected]*.insane:

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, on 2 different media, 1 copy offsite/offline). This is the single most critical defense. Test your backups regularly.
  • Software Updates & Patching: Keep your operating system, applications (browsers, plugins, office suites, PDF readers), and antivirus software up-to-date. Patching known vulnerabilities closes doors for attackers.
  • Strong Passwords & Multi-Factor Authentication (MFA): Use complex, unique passwords for all accounts and enable MFA wherever possible, especially for critical systems and cloud services.
  • Endpoint Detection and Response (EDR) / Antivirus (AV): Deploy reputable EDR/AV solutions and ensure they are always active and updated. Many modern EDR solutions offer behavioral analysis that can detect ransomware activities even without specific signatures.
  • Email Security: Implement robust spam filters and educate users about phishing, suspicious attachments, and untrusted links.
  • Network Segmentation: Isolate critical systems and sensitive data from the rest of the network to limit lateral movement in case of a breach.
  • Disable Unnecessary Services: Disable RDP if not needed, or secure it with strong passwords and network-level authentication. Disable SMBv1.
  • User Education: Train employees to recognize and avoid common ransomware attack vectors, especially suspicious downloads and emails.
  • Application Whitelisting: Restrict the execution of unauthorized applications on endpoints.

2. Removal

If your system is infected, follow these steps for effective removal:

  1. 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.
  2. Do NOT Pay the Ransom: Paying the ransom encourages attackers and there’s no guarantee you’ll receive a working decryption key.
  3. Identify the Ransomware: The [email protected] extension clearly identifies it as a Djvu/STOP variant. Look for the ransom note, typically named _readme.txt, which will contain instructions and the contact email.
  4. Scan and Remove Malware:
    • Boot the infected system into Safe Mode with Networking (if possible) or Safe Mode.
    • Run a full scan with a reputable antivirus/anti-malware program (e.g., Malwarebytes, Windows Defender, ESET, Sophos). Ensure the definitions are updated.
    • Consider using specialized tools like Emsisoft Emergency Kit or Dr.Web CureIt! for a second opinion scan.
    • The ransomware often modifies system settings, disables security software, and deletes Volume Shadow Copies. Your security software should help revert these changes.
  5. Check for Persistence: Examine common persistence locations:
    • Startup folders (shell:startup, shell:common startup)
    • Registry Run keys (HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run, HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run)
    • Scheduled Tasks (schtasks /query)
    • Services (services.msc)
    • The ransomware executable itself might be hidden in %APPDATA% or %LOCALAPPDATA% directories.
  6. Delete Malicious Files: Once identified, carefully delete all ransomware-related files and registry entries. Let your security software handle this, but verify.
  7. Change All Passwords: Assume credentials on the infected machine might have been compromised. Change all passwords, especially for any accounts logged into or accessed from the compromised system.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • Offline Keys: If your system was infected while offline (no internet connection), the ransomware might have used a limited set of “offline keys.” In such cases, there is a possibility of decryption using a public decryptor.
    • Online Keys: If your system was online during the infection, the ransomware typically generates a unique “online key” for your specific system. Decryption for files encrypted with an online key is generally NOT possible without the specific private key from the attackers. No public decryptor can help with online keys.
    • Emsisoft Decryptor for STOP Djvu: Emsisoft, in cooperation with security researchers, provides a free decryptor for many STOP/Djvu variants. You can download it from their official website.
      • How to Use: The decryptor requires the _readme.txt ransom note and at least one encrypted file. It will try to determine if your key is an “offline key” and attempt decryption. If it determines an “online key” was used, decryption is not currently feasible.
      • Important Note: The decryptor needs to be executed on a clean, uninfected system (or after thorough removal of the ransomware) and pointed to the encrypted files.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP Djvu: The primary tool for potential decryption (for offline keys).
    • Reputable Antivirus/Anti-Malware Software: For removal and ongoing protection (e.g., Malwarebytes, Windows Defender, Bitdefender, Kaspersky, ESET).
    • Data Recovery Software (Limited Use): Tools like ShadowExplorer or built-in Windows “Previous Versions” might help recover older, unencrypted versions of files IF Volume Shadow Copies were not deleted by the ransomware (Djvu often deletes them).
    • Operating System Patches & Updates: Keep Windows/macOS/Linux updated to protect against common vulnerabilities.
    • Browser Security Extensions: Use ad-blockers and script-blockers to reduce exposure to malvertising and malicious scripts.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note (_readme.txt): This file is typically dropped in every folder containing encrypted files and on the desktop. It contains the attacker’s email ([email protected]) and a unique personal ID for the victim. Keep this note, as the personal ID is crucial for potential decryption attempts.
    • Disabling Security Features: This variant, like other Djvu ransomware, commonly attempts to disable Windows Defender and other installed antivirus software, and delete Volume Shadow Copies to prevent easy recovery.
    • Host File Modification: The ransomware may modify the Windows hosts file to block access to legitimate security and antivirus websites, preventing victims from downloading remediation tools. Check and reset your hosts file (C:\Windows\System32\drivers\etc\hosts).
    • “Info.exe” or “Build.exe” Drops: Often, the initial infection drops other executable files (e.g., info.exe, build.exe) that might contain system information or further malware. Ensure these are removed.
  • Broader Impact:
    • Significant Data Loss: For victims without robust backups and whose files are encrypted with “online keys,” data loss can be permanent.
    • Operational Disruption: Individuals and small businesses can experience severe disruption due to inaccessible files, leading to lost productivity and financial strain.
    • Financial Burden: The costs associated with incident response, system cleanup, potential data recovery services, and lost business can be substantial.
    • Psychological Stress: Being a victim of ransomware is often a highly stressful experience, especially for individuals or small organizations dependent on their data.
    • Reputation Damage: For businesses, a ransomware attack can lead to a loss of customer trust and reputational harm.

In summary, the *[email protected]*.insane ransomware is a persistent threat from the Djvu/STOP family. While removal is generally straightforward with good antivirus tools, file decryption remains challenging for “online key” victims. The most effective defense remains prevention through robust backups, diligent software updates, and vigilant user behavior.