*[email protected]*.костя

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This document provides a detailed technical breakdown and comprehensive recovery strategies for the ransomware variant identified by the file extension *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ. This variant is a derivative of the prolific STOP/Djvu ransomware family.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this ransomware is *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ. This string is appended to the original file name, typically after an initial unique ID (though the * in the provided string implies it’s directly appended). The Cyrillic part ÐºÐ¾Ñ Ñ‚Ñ translates roughly to “bone” or “cost” in Russian.
  • Renaming Convention: The ransomware modifies filenames by appending its unique extension.
    • Example: A file named document.docx would be renamed to [email protected]*.ÐºÐ¾Ñ Ñ‚Ñ.
    • This pattern is consistent with STOP/Djvu variants, where the email address and a specific identifier are used as the final extension.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Variants like *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ, being part of the STOP/Djvu family, are continuously released. While a precise “start date” for this specific string is difficult to pinpoint without specific threat intelligence reports, the STOP/Djvu family has been highly active since late 2018/early 2019, with new versions and extensions appearing almost daily. This particular variant likely emerged in late 2023 or early 2024, following the established pattern of new STOP/Djvu releases.

3. Primary Attack Vectors

The *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ variant, consistent with the STOP/Djvu family, primarily relies on social engineering and deceptive distribution methods:

  • Cracked Software & Illegitimate Downloads: This is the most prevalent vector. Users seeking pirated software (e.g., activators, keygens, cracks for Windows, Microsoft Office, Photoshop, games) download malicious installers bundled with the ransomware. These are often found on torrent sites, shady software download portals, or compromised file-sharing platforms.
  • Fake Software Updates: Pop-up ads or deceptive websites prompting users to “update” their browser (e.g., Flash Player, Java, Chrome) often lead to the download of the ransomware payload.
  • Malicious Email Attachments: While less common for Djvu than for some other ransomware families, email phishing campaigns delivering archives or documents with embedded malicious scripts can be used.
  • Bundled Software: The ransomware can be disguised as legitimate software or bundled with freeware/shareware downloads without the user’s explicit consent.
  • Compromised Websites: Drive-by downloads from compromised websites, though less frequent for this family, can also serve as an infection vector.
  • Remote Desktop Protocol (RDP) Exploits (Less Common): While not a primary vector for Djvu, poorly secured RDP endpoints can be brute-forced or exploited, allowing attackers to manually deploy the ransomware. However, this is more typical for enterprise-level ransomware rather than Djvu’s usual targets.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against ransomware like *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ:

  • Robust Backups: Implement a 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 (e.g., external hard drive disconnected when not in use, cloud storage). Test your backups regularly.
  • Software Updates: Keep your operating system (Windows, macOS, Linux) and all software (browsers, antivirus, applications) fully patched and up-to-date. This closes security vulnerabilities that ransomware might exploit.
  • Reliable Antivirus/Anti-malware: Use a reputable cybersecurity suite with real-time protection and keep its definitions updated. Enable all security features like heuristic analysis and behavioral detection.
  • Firewall Configuration: Maintain an active firewall (Windows Defender Firewall or third-party) to block unauthorized network connections.
  • User Awareness Training: Educate users about the dangers of phishing emails, suspicious attachments, unsolicited links, and the risks associated with downloading pirated or untrusted software.
  • Ad Blockers: Use browser ad-blockers to prevent accidental clicks on malicious advertisements.
  • Disable RDP if Unused: If Remote Desktop Protocol is not essential, disable it. If required, secure it with strong, unique passwords, multi-factor authentication (MFA), and restrict access to trusted IPs only.
  • Principle of Least Privilege: Limit user permissions to only what is necessary for their tasks to reduce the impact of a breach.

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 your network or further encrypting shared drives.
  2. Identify and Stop Malicious Processes:
    • Boot the computer into Safe Mode with Networking (or Safe Mode if you don’t need network access for downloading tools). This loads only essential drivers and services, often preventing the ransomware from fully executing.
    • Open Task Manager (Ctrl+Shift+Esc) and look for suspicious processes consuming high CPU or memory, especially unfamiliar ones. End them if possible.
  3. Scan with Reputable Anti-malware:
    • Use a high-quality antivirus/anti-malware tool (e.g., Malwarebytes, ESET, Bitdefender, Sophos) to perform a full system scan. Ensure the definitions are up-to-date.
    • Remove or quarantine all detected threats. Multiple scans with different tools might be beneficial.
  4. Remove Persistence Mechanisms:
    • Check Startup programs (Task Manager -> Startup tab) for any suspicious entries.
    • Check Scheduled Tasks (Task Scheduler) for new, unauthorized tasks designed to re-execute the ransomware.
    • Examine Registry Editor (regedit.exe) in HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run and HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run for unusual entries. Exercise extreme caution when editing the registry.
  5. Delete Malicious Files: After scanning, manually delete any remaining suspicious files, especially executables found in temporary folders (%temp%), AppData folders (%appdata%, %localappdata%), or user profile folders.
  6. Reboot and Rescan: Reboot the system into normal mode and perform another full system scan to ensure all traces are removed.

Important Note: Removing the ransomware itself does not decrypt your files. It only stops further encryption and cleans the infection.

3. File Decryption & Recovery

  • Recovery Feasibility: The feasibility of decrypting files encrypted by *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ (a STOP/Djvu variant) depends heavily on the encryption key used:

    • Online Key: If the infected system had an active internet connection to the ransomware’s command-and-control (C2) server during encryption, a unique “online key” is generated for that specific victim. In this case, decryption without paying the ransom and receiving the private key from the attackers is extremely difficult, if not impossible.
    • Offline Key: If the system was offline or unable to connect to the C2 server during encryption, the ransomware typically resorts to using a pre-defined “offline key.” If security researchers have managed to obtain this specific offline key and integrate it into a decryptor tool, then decryption might be possible.

  • Methods or Tools Available:

    1. Emsisoft Decryptor for STOP Djvu: The Emsisoft Decryptor for STOP Djvu is the primary tool for attempting decryption. It works by analyzing the encrypted files and attempting to match them with known online or offline keys.
      • How it works: You download the tool, select the encrypted folder(s), and it attempts to identify the ransomware variant and the key type. If an offline key is used and known, it can decrypt files. If an online key was used, it will inform you that decryption is currently not possible, but it may still be useful to identify the specific key ID.
      • Availability: Downloadable from the Emsisoft website or linked via the No More Ransom project.
    2. No More Ransom Project: Visit the No More Ransom website. Upload a sample of your encrypted file and the ransom note. This platform can often identify the ransomware variant and direct you to available decryptors, if any exist.
    3. Shadow Volume Copies (VSS): The ransomware often attempts to delete Shadow Volume Copies using vssadmin.exe delete shadows /all /quiet. However, if this command fails or if the ransomware didn’t run with sufficient privileges, some shadow copies might remain. You can try recovering previous versions of files or folders using Windows’ built-in “Previous Versions” feature (right-click on a file/folder -> Properties -> Previous Versions).
    4. Data Recovery Software: Tools like PhotoRec, Recuva, or EaseUS Data Recovery Wizard might be able to recover deleted original files if they haven’t been overwritten by new data. This is a long shot but worth attempting on critical files.
    5. Backups: The most reliable method. Restore your data from clean, uninfected backups created before the infection.

  • Essential Tools/Patches:

    • Antivirus/Anti-malware: Modern solutions for initial cleanup.
    • Emsisoft Decryptor for STOP Djvu: The go-to tool for decryption attempts.
    • Windows Security Updates: Keep your OS updated to patch vulnerabilities.
    • Firewall: For network protection.
    • Backup Solutions: Crucial for recovery if decryption is not possible.

4. Other Critical Information

  • Additional Precautions/Unique Characteristics:

    • Ransom Note: This variant will leave a ransom note, typically named _readme.txt, in every folder containing encrypted files and on the desktop. This note contains instructions on how to contact the attackers (usually via the email [email protected] and sometimes a secondary email like [email protected] or [email protected]) and details the ransom amount (typically $490 or $980, often with a discount for early payment).
    • Info-Stealer Payload: Many STOP/Djvu variants, including newer ones, often drop and execute an information-stealing Trojan (such as Vidar Stealer, Azorult, or Predator The Thief) before encryption. This Trojan steals passwords, cryptocurrency wallet information, browser data, and other sensitive details, adding another layer of compromise beyond just file encryption.
    • Hosts File Modification: The ransomware may modify the Windows hosts file (C:\Windows\System32\drivers\etc\hosts) to block access to security-related websites (e.g., antivirus vendor sites, tech forums) to prevent victims from seeking help or downloading security tools.
    • Deletion of Shadow Copies: It actively attempts to delete Volume Shadow Copies to hinder recovery efforts via “Previous Versions.”

  • Broader Impact:

    • Widespread Consumer Impact: STOP/Djvu is one of the most widespread ransomware families targeting individual users and small businesses due to its reliance on common vectors like cracked software. Its low-cost distribution makes it highly effective at reaching a broad, less tech-savvy audience.
    • Financial and Data Loss: Victims face not only the potential loss of irrecoverable data but also significant financial costs, whether from paying the ransom (which is not recommended and does not guarantee decryption) or from hiring IT professionals for recovery.
    • Privacy Compromise: The inclusion of info-stealers means that sensitive personal and financial data may also be compromised, leading to identity theft, financial fraud, or further targeted attacks.
    • Ongoing Threat: The continuous release of new variants with different extensions ensures that STOP/Djvu remains a persistent and evolving threat in the ransomware landscape.

This resource should provide a solid foundation for understanding and combating the *[email protected]*.ÐºÐ¾Ñ Ñ‚Ñ ransomware variant. Always prioritize prevention and maintaining robust backups to protect against such threats.