*[email protected]*

[Content by Gemini 2.5]

This document provides a comprehensive overview of the ransomware variant identifiable by the file extension *[email protected]*. Based on the naming convention, this variant is strongly indicative of being a new or re-branded strain belonging to the prolific STOP/DJVU ransomware family. This family is known for appending unique identifiers and attacker contact information (often email addresses) to encrypted files.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file extension used by this variant will be [email protected].
  • Renaming Convention: When a file is encrypted by this ransomware, its original name will be modified to append this specific string. The pattern is typically:
    [original_filename].[original_extension][email protected]
    For example:
    • document.docx might become [email protected]
    • photo.jpg might become [email protected]
      Alongside the encrypted files, a ransom note will be dropped in directories containing encrypted files, usually named _readme.txt. This note will detail the ransom demand and provide instructions for contacting the attackers, typically via the [email protected] email address, and often a secondary one.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While a specific “start date” for the [email protected] variant itself is difficult to pinpoint without widespread public reporting specific to this exact strain, it likely emerged as part of the ongoing, continuous evolution of the STOP/DJVU ransomware family. The STOP/DJVU family has been active since late 2017/early 2018 and consistently releases new variants, sometimes on a daily basis, making it one of the most prevalent ransomware threats targeting individual users and small businesses globally. New variants often use a different extension (like this one) or a different contact email.

3. Primary Attack Vectors

The *[email protected]* variant, like other STOP/DJVU strains, primarily relies on social engineering and deceptive tactics rather than exploiting complex network vulnerabilities directly. Common propagation mechanisms include:

  • Cracked Software/Pirated Content: This is the most prevalent vector. Users download torrents, key generators, software cracks, fake installers, or pirated games from unofficial websites. The ransomware payload is often bundled within these seemingly legitimate, but malicious, downloads.
  • Malicious Websites and Fake Updates: Visiting compromised websites or clicking on deceptive pop-ups that claim to offer software updates (e.g., Flash Player, Java, browser updates) can lead to the download and execution of the ransomware.
  • Email Phishing Campaigns: While less common than cracked software for STOP/DJVU, malicious attachments (e.g., infected documents, fake invoices, shipping notifications) or links in phishing emails can also deliver the payload.
  • Malvertising: Deceptive advertisements on legitimate or illegitimate websites can redirect users to malicious landing pages that automatically download the ransomware or trick users into downloading it.
  • Bundled Freeware: The ransomware may be silently installed alongside legitimate freeware or shareware downloaded from less reputable sources.

Remediation & Recovery Strategies:

1. Prevention

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

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies of data, on 2 different media types, with 1 copy off-site or air-gapped). Test your backups regularly. This is your most critical recovery tool.
  • Robust Endpoint Security: Deploy and maintain up-to-date antivirus and Endpoint Detection and Response (EDR) solutions on all devices. Configure them for real-time protection and regularly schedule full system scans.
  • Software Updates & Patch Management: Keep your operating system, web browsers, antivirus software, and all other applications fully patched and updated. Exploits often target known vulnerabilities.
  • User Education: Train users to recognize and avoid phishing attempts, suspicious links, and unofficial software download sources. Emphasize the dangers of pirated software and cracked executables.
  • Strong Password Policies & Multi-Factor Authentication (MFA): Implement strong, unique passwords for all accounts and enable MFA wherever possible, especially for remote access services.
  • Network Segmentation: Isolate critical systems and data to limit the lateral movement of ransomware in case of an infection.
  • Disable Unnecessary Services: Disable SMBv1, RDP if not strictly needed, or secure RDP with strong authentication, VPNs, and IP whitelisting.

2. Removal

If your system is infected, follow these steps for cleanup:

  • Immediate Isolation: Disconnect the infected system(s) from the network (Wi-Fi, Ethernet) immediately to prevent further spread to other devices or network shares.
  • Identify & Terminate Processes: Use Task Manager or a more advanced process explorer to identify and terminate any suspicious processes. Be cautious, as some ransomware processes may masquerade as legitimate system processes.
  • Scan with Reputable Anti-Malware: Boot into Safe Mode with Networking (if necessary) and perform a full system scan using a trusted and up-to-date anti-malware solution (e.g., Malwarebytes, Windows Defender, Bitdefender). Allow the software to quarantine or remove all detected threats.
  • Check for Persistent Mechanisms: Scan for new or modified registry entries, scheduled tasks, or startup programs that the ransomware might have created to ensure it doesn’t re-launch after a reboot.
  • Do Not Pay the Ransom: Paying the ransom does not guarantee file recovery and incentivizes further attacks. There’s no guarantee the attackers will provide a working decryptor.
  • Change All Passwords: Assume that credentials on the infected system may have been compromised. Change all passwords for accounts accessed from the infected machine, especially for online services.

3. File Decryption & Recovery

  • Recovery Feasibility: Decrypting files encrypted by STOP/DJVU variants (including *[email protected]*) is highly challenging and often impossible without the attacker’s private key, particularly for newer infections.
    • Online Keys: Most modern STOP/DJVU variants use “online keys” which are unique, server-generated encryption keys for each victim. If the ransomware successfully communicates with its command-and-control (C2) server, it obtains this unique online key. Without this specific key, decryption is virtually impossible.
    • Offline Keys: In rare cases, if the ransomware fails to connect to its C2 server (e.g., due to network issues, firewall blocking), it may use a pre-determined “offline key.” If enough victims are infected with the same offline key, security researchers might eventually be able to derive it and develop a decryptor.
  • Essential Tools/Patches:
    • Emsisoft Decryptor for STOP/DJVU: Emsisoft, in collaboration with Michael Gillespie, provides a free decryptor for STOP/DJVU ransomware. This tool only works if your files were encrypted with an “offline key” that has been recovered by researchers, or if your unique online key has been compromised or obtained. You can submit an encrypted file to their tool to check if a decryption key is available. Be aware that success rates are low for recent variants due to the prevalent use of online keys.
    • Data Recovery Software: For unencrypted files that might have been deleted or corrupted during the attack, data recovery software might retrieve some data, but not the encrypted files themselves.
    • System Restore/Shadow Copies: While ransomware often deletes or encrypts Shadow Volume Copies, it’s worth checking if any unencrypted restore points or shadow copies exist that predate the infection. This is a rare success story, but possible.
    • Professional Data Recovery Services: As a last resort, specialized data recovery companies might offer services, but these are often very expensive and success is not guaranteed for heavily encrypted data.

4. Other Critical Information

  • Additional Precautions:
    • Information Stealer Component: A significant characteristic of many STOP/DJVU variants, including potentially *[email protected]*, is that they often bundle an information-stealing malware (e.g., Vidar, RedLine Stealer, AZORult). This means that beyond file encryption, your sensitive data (browser passwords, cryptocurrency wallet keys, session cookies, etc.) may have been exfiltrated by the attackers. Assume your accounts and personal data are compromised. Take immediate steps to change passwords, monitor financial accounts, and enable MFA everywhere.
    • Fake Decryptors: Be extremely wary of websites or services claiming to offer guaranteed decryption tools for a fee. Many of these are scams designed to extract more money from victims or to install additional malware.
  • Broader Impact:
    • The STOP/DJVU family, including variants like *[email protected]*, has had an immense impact on individual users and small businesses due to its pervasive distribution via common download channels.
    • The constant release of new variants with unique online keys makes post-infection recovery exceedingly difficult, forcing many victims to either lose their data or pay the ransom.
    • The bundled information stealer adds a critical layer of data breach risk, making the incident much more severe than simple file encryption. Victims must consider identity theft and financial fraud as potential consequences.