@mail.ru*

[Content by Gemini 2.5]

This document provides a comprehensive overview of ransomware variants that utilize the @mail.ru* pattern in their file extensions, commonly associated with families like Dharma (Crisis), Phobos, and GlobeImposter. While @mail.ru* is not a single, distinct ransomware family, it’s a frequently observed characteristic indicating an attack by these or similar strains that use the attackers’ email addresses (often from the mail.ru domain) to identify victims and facilitate communication for ransom payment.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Ransomware variants using the @mail.ru* pattern typically append a string that includes the attacker’s email address, often ending in @mail.ru, to the encrypted files. The exact format varies widely but generally follows one of these structures:

  • Renaming Convention: The typical file renaming pattern involves taking the original filename and extension, then appending a unique victim ID (often hexadecimal or alphanumeric), followed by the attacker’s @mail.ru email address, and sometimes a final fixed extension unique to the specific strain.

    • Example: document.docx might become document.docx.id-1234ABCD.[[email protected]].cezar or document.docx.id-ABCDEFGH.[[email protected]].wallet.
    • The purpose of including the email address directly in the file extension is to provide clear instructions to the victim on how to contact the attackers for decryption, without needing to find a separate ransom note. However, a ransom note is almost always dropped as well (e.g., info.txt, files.txt, README.txt, README.hta).

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: While ransomware using various email domains has existed for years, the prominent use of @mail.ru email addresses as part of the file extension and in ransom notes for widespread attacks, particularly by variants of Dharma, Phobos, and GlobeImposter, gained significant traction and became widespread from mid-2017 through 2020 and continues to evolve. These families have seen numerous iterations and affiliate groups, making specific “start dates” difficult for the pattern itself, but their surge was largely tied to the increase in RDP brute-forcing and exploitation.

3. Primary Attack Vectors

Ransomware variants using the @mail.ru* pattern commonly employ a combination of the following propagation mechanisms:

  • Remote Desktop Protocol (RDP) Exploitation/Brute-forcing: This is one of the most prevalent attack vectors. Attackers scan the internet for open RDP ports, then use brute-force attacks or compromised credentials to gain unauthorized access. Once inside, they manually deploy the ransomware.
  • Phishing Campaigns:
    • Malicious Attachments: Emails containing seemingly legitimate attachments (e.g., invoices, shipping notifications, resumes) that, when opened, execute malicious code (e.g., macros in Office documents, JavaScript files, ZIP archives containing executables) to download and run the ransomware.
    • Malicious Links: Emails with links that direct users to compromised websites hosting exploit kits, or to fake login pages designed to harvest credentials that can later be used for RDP access or other intrusions.
  • Software Vulnerabilities: Exploitation of known vulnerabilities in unpatched software, operating systems, or network services (e.g., SMB vulnerabilities like EternalBlue, vulnerabilities in VPN appliances, web servers, or content management systems) to gain initial access or move laterally within a network.
  • Supply Chain Attacks: While less common for smaller groups, some more sophisticated operations might compromise software update mechanisms or legitimate developer tools to distribute ransomware through trusted channels.
  • Compromised Credentials: Purchase of stolen credentials (e.g., VPN logins, domain administrator accounts) from dark web marketplaces to gain initial access.
  • Drive-by Downloads: Users visiting compromised or malicious websites may unknowingly download and execute the ransomware without interaction.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to minimize the risk of infection by @mail.ru* ransomware variants:

  • Regular Data Backups: Implement a robust 3-2-1 backup strategy (3 copies, 2 different media types, 1 offsite/offline). Ensure backups are immutable, tested regularly, and stored securely, isolated from the network to prevent them from being encrypted.
  • Strong Password Policies & Multi-Factor Authentication (MFA): Enforce complex, unique passwords for all accounts, especially administrative and RDP accounts. Implement MFA wherever possible, particularly for VPNs, RDP gateways, and critical internal systems.
  • Patch Management: Regularly update and patch operating systems, software, and firmware, prioritizing critical vulnerabilities, especially those related to RDP, SMB, and publicly exposed services.
  • Network Segmentation: Divide your network into smaller, isolated segments to limit lateral movement of ransomware if an initial breach occurs.
  • Principle of Least Privilege: Grant users and applications only the minimum necessary permissions to perform their tasks. Restrict RDP access to a “need-to-have” basis and place it behind a VPN or gateway.
  • Endpoint Detection and Response (EDR) / Antivirus (AV): Deploy modern EDR solutions and keep traditional antivirus software up-to-date with real-time scanning enabled. Configure them to block suspicious processes and network connections.
  • Email Security Gateway & User Training: Implement advanced email filtering to block malicious attachments and links. Conduct regular cybersecurity awareness training for employees to recognize phishing attempts and suspicious emails.
  • Disable or Restrict RDP: If RDP must be used, secure it by:
    • Using strong, unique passwords and MFA.
    • Placing RDP behind a VPN.
    • Changing the default RDP port (3389).
    • Implementing account lockout policies.
    • Monitoring RDP login attempts for anomalies.

2. Removal

Effective removal of @mail.ru* ransomware involves a systematic approach:

  • 1. Isolate Infected Systems: Immediately disconnect infected machines from the network (unplug network cables, disable Wi-Fi) to prevent further spread.
  • 2. Identify the Ransomware Process: Use Task Manager, Process Explorer, or forensic tools to identify the malicious process. Look for unusual or high CPU/disk usage processes.
  • 3. Terminate Malicious Processes: End the identified ransomware process.
  • 4. Scan with Antivirus/Anti-Malware: Boot the system into Safe Mode with Networking (if possible, otherwise use a rescue disk) and perform a full system scan using up-to-date antivirus/anti-malware software (e.g., Malwarebytes, Windows Defender Offline). Remove all detected threats.
  • 5. Check Startup Entries and Persistence Mechanisms: Review system startup folders, Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run), and Scheduled Tasks for any persistence mechanisms left by the ransomware. Remove any suspicious entries.
  • 6. Patch Vulnerabilities: Identify and patch the vulnerability or weak point that allowed the ransomware in (e.g., close open RDP ports, update unpatched software).
  • 7. Change Credentials: Force a password reset for all user accounts, especially administrative accounts, as credentials might have been compromised.

3. File Decryption & Recovery

  • Recovery Feasibility:

    • Without Paying the Ransom: Decryption without the attacker’s key is often extremely difficult or impossible for modern, well-implemented ransomware variants, including many of those using the @mail.ru* pattern. This is because they use strong, asymmetric encryption algorithms.
    • Available Decryptors: For older or specific variants of Dharma, Phobos, or GlobeImposter, free decryptors might be available through initiatives like No More Ransom (www.nomoreransom.org). It is highly recommended to upload an encrypted file and the ransom note to their Crypto Sheriff tool to identify the specific ransomware and check for available decryptors.
    • Backups are Key: The most reliable and recommended method for file recovery is to restore from clean, verified backups created before the infection.
    • Paying the Ransom: While some organizations choose to pay the ransom as a last resort, it is generally not recommended. There is no guarantee that attackers will provide a working decryptor, and it encourages further criminal activity. Engage with law enforcement and cybersecurity experts before considering payment.

  • Essential Tools/Patches:

    • Antivirus/Anti-Malware Software: Reputable solutions like Bitdefender, Kaspersky, Sophos, ESET, Malwarebytes, and Windows Defender.
    • Vulnerability Scanners: Tools like Nessus, OpenVAS, or Qualys to identify system weaknesses.
    • Network Monitoring Tools: To detect suspicious RDP connections, brute-force attempts, or unusual outbound traffic.
    • Operating System Patches: Regularly applied security updates for Windows, macOS, Linux, etc.
    • RDP Gateway/VPN Solutions: For securing RDP access.
    • Backup & Recovery Software: Ensure your chosen solution supports immutable backups and quick restoration.

4. Other Critical Information

  • Additional Precautions:

    • Data Exfiltration (Double Extortion): Be aware that some ransomware groups, including newer iterations of those often linked to the @mail.ru* pattern, not only encrypt data but also exfiltrate sensitive information before encryption. If data exfiltration is suspected, a data breach notification process should be initiated in accordance with relevant regulations (e.g., GDPR, CCPA).
    • Ransom Note Analysis: Carefully analyze the ransom note. It may contain specific instructions, unique IDs, or details that can help identify the exact ransomware variant, which is crucial for checking for existing decryptors.
    • Professional Incident Response: For organizations, engaging a professional incident response team is highly recommended. They can perform forensic analysis, ensure complete eradication, and help with recovery, minimizing business disruption and future risks.
    • Law Enforcement Notification: Report the incident to relevant law enforcement agencies (e.g., FBI, local police, national CERTs).

  • Broader Impact:

    • Financial Loss: Direct costs from ransom payments (if made), recovery efforts, lost revenue due to downtime, and potential legal fees or regulatory fines.
    • Operational Disruption: Significant downtime for critical systems, leading to severe business interruption, inability to serve customers, and potential loss of data or intellectual property.
    • Reputational Damage: Loss of customer trust, negative media coverage, and damage to brand image.
    • Long Recovery Times: Recovery from a significant ransomware attack can take weeks or even months, requiring substantial resources and effort.
    • Supply Chain Risk: If an organization within a supply chain is infected, it can have ripple effects on partners and customers.

By understanding the technical characteristics and implementing robust prevention, removal, and recovery strategies, individuals and organizations can significantly bolster their defenses against @mail.ru* ransomware and similar threats.