*[email protected]*.mers

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This document provides a comprehensive overview of the ransomware variant identified by the file extension *[email protected]*.mers, offering insights into its technical characteristics and practical recovery strategies.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends the exact string [email protected] to encrypted files.
  • Renaming Convention: When a file is encrypted by this variant, its original name is typically preserved, but the .[original_extension][email protected] suffix is added.
    • Example: A file named document.docx would be renamed to [email protected].
    • Example: An image file photo.jpg would become [email protected].
      This pattern is highly indicative of ransomware families that often use builder kits, such as derivatives of Dharma (also known as Dharma/Phobos/CrySiS) or similar ransomware-as-a-service (RaaS) offerings, where the threat actor’s contact email is embedded directly into the file extension.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Specific public reports detailing the initial outbreak of the *[email protected]*.mers variant are not widely documented as a standalone, major campaign. However, the naming convention (email address as part of the extension) became prevalent in variants appearing from late 2018 through 2023, often associated with strains derived from or mimicking the Phobos and Dharma ransomware families. It likely represents a specific build or iteration used by a smaller group or individual threat actor during this period, rather than a globally coordinated major ransomware operation.

3. Primary Attack Vectors

The *[email protected]*.mers variant, consistent with other ransomware using similar naming conventions, primarily relies on the following propagation mechanisms:

  • Remote Desktop Protocol (RDP) Exploitation: This is one of the most common vectors. Threat actors often:
    • Brute-force weak RDP credentials: Attempting to guess usernames and passwords.
    • Exploit RDP vulnerabilities: Such as unpatched BlueKeep (CVE-2019-0708) or other flaws that allow remote code execution or unauthorized access.
      Once access is gained, the ransomware payload is manually deployed and executed by the attacker.
  • Phishing Campaigns: Malicious emails are designed to trick users into:
    • Opening malicious attachments: Such as seemingly legitimate documents (e.g., invoices, resumes) containing macros or embedded scripts that download and execute the ransomware.
    • Clicking on malicious links: Leading to compromised websites hosting exploit kits, or fake login pages to steal credentials which are then used for RDP access or other remote entry.
  • Software Vulnerabilities: Exploitation of unpatched vulnerabilities in:
    • Operating Systems: Outdated Windows versions with known security flaws.
    • Network Devices: Routers, firewalls, or VPN servers with exploitable weaknesses.
    • Common Software Applications: Weaknesses in popular business software or content management systems.
  • Supply Chain Attacks / Software Cracks:
    • Compromised legitimate software: Distribution of ransomware through seemingly legitimate software updates or bundled with cracked/pirated software downloaded from unofficial sources.
    • Malvertising: Driving users to malicious sites that serve the ransomware payload.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are the most effective defense against *[email protected]*.mers and similar ransomware threats:

  • Robust Backup Strategy: Implement a 3-2-1 backup rule:
    • 3 copies of your data.
    • On 2 different media types.
    • With 1 copy offsite/offline (air-gapped) to prevent ransomware from encrypting backups.
  • Patch Management: Regularly update operating systems, applications, and firmware to patch known vulnerabilities. Enable automatic updates where feasible and monitor patch releases.
  • Strong Password Policies & Multi-Factor Authentication (MFA): Enforce complex, unique passwords for all accounts, especially for RDP, VPN, and critical systems. Implement MFA wherever possible, particularly for remote access services.
  • Network Segmentation: Divide your network into isolated segments to limit lateral movement of ransomware in case of a breach.
  • Endpoint Detection and Response (EDR) / Antivirus (AV): Deploy reputable EDR/AV solutions with real-time protection and behavioral analysis capabilities. Keep definitions updated.
  • Email Security: Implement strong email filtering, spam protection, and sandboxing solutions to detect and block malicious attachments and links.
  • User Awareness Training: Educate employees about phishing, suspicious emails, and safe browsing practices. Conduct regular simulated phishing exercises.
  • Disable Unused Services: Deactivate or restrict access to services like RDP if not strictly necessary. If RDP is required, place it behind a VPN, use strong authentication, and monitor its usage closely.

2. Removal

If an infection by *[email protected]*.mers is detected, follow these steps to remove it:

  1. Isolate Infected Systems: Immediately disconnect infected computers from the network (physically or by disabling network adapters) to prevent further spread.
  2. Identify and Terminate Malicious Processes: Use Task Manager, Process Explorer, or similar tools to identify unusual or high-CPU/disk usage processes. Terminate them if confident they are malicious.
  3. Scan and Remove Malware: Boot the infected system into Safe Mode with Networking (if necessary to download tools) or use a clean bootable USB drive with an updated anti-malware scanner. Perform a full system scan using reputable tools like:
    • Malwarebytes
    • Emsisoft Emergency Kit
    • Kaspersky Virus Removal Tool
    • Microsoft Defender Offline
  4. Remove Persistence Mechanisms: Check common persistence locations for malicious entries:
    • Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run, HKLM\Software\Microsoft\Windows\CurrentVersion\Run)
    • Startup folders
    • Scheduled Tasks (schtasks)
    • Windows Services
  5. Restore Shadow Copies: Ransomware often attempts to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet). Check if they are still present. If so, they might be used for file recovery (though often not reliable for ransomware).
  6. Change Credentials: After ensuring the system is clean, change all passwords that might have been compromised, especially RDP credentials or network share passwords.

3. File Decryption & Recovery

  • Recovery Feasibility: As of the latest information, there is no universally effective or publicly available decryption tool specifically for the *[email protected]*.mers variant. This is common for ransomware that uses unique keys per infection or is a minor iteration of a family with robust encryption. While decryption may theoretically be possible if the encryption scheme is flawed or the master key is leaked, relying on this is not a viable recovery strategy.
  • Primary Recovery Method: The most reliable method for file recovery is restoring from unencrypted, air-gapped, and recent backups. If you have followed the backup recommendations, this will be your primary path to data recovery.
  • Essential Tools/Patches:
    • For Prevention:
      • Operating System Updates: Keep Windows and other OS components fully patched.
      • Security Software: Use up-to-date EDR/AV solutions (e.g., CrowdStrike, SentinelOne, Microsoft Defender for Endpoint, Bitdefender, ESET).
      • Backup Solutions: Implement reliable backup software (e.g., Veeam, Acronis, dedicated cloud backup services).
    • For Remediation:
      • Bootable Anti-Malware Tools: Tools like Emsisoft Emergency Kit or Kaspersky Virus Removal Tool are invaluable for deep scans on infected systems.
      • Process Monitoring Tools: Sysinternals Process Explorer to identify suspicious processes.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note: This ransomware variant, like many others of its type, will likely drop a ransom note (e.g., info.txt, README.txt, or FILES ENCRYPTED.txt) on the desktop and in affected folders. This note typically contains instructions for contacting the attackers via the [email protected] email address and demands payment in cryptocurrency (usually Bitcoin) for decryption. It is strongly advised against paying the ransom, as there is no guarantee of decryption, and it fuels the ransomware ecosystem.
    • Data Exfiltration Risk: While not explicitly known for *[email protected]*.mers, many modern ransomware variants also engage in data exfiltration (stealing sensitive data before encryption) for double extortion. Assume sensitive data may have been compromised and plan accordingly (e.g., notify affected parties, monitor for identity theft).
  • Broader Impact: The broader implications of an infection by *[email protected]*.mers include:
    • Significant Data Loss: If backups are unavailable or compromised.
    • Business Interruption: Downtime, loss of productivity, and inability to access critical systems and data.
    • Financial Costs: Recovery efforts, potential ransom payment (not recommended), legal fees, and reputational damage.
    • Supply Chain Risk: If the infected system is part of a larger supply chain, the impact can propagate to partners and customers.

By adhering to robust cybersecurity hygiene, maintaining comprehensive backups, and being prepared for incident response, organizations and individuals can significantly mitigate the risk and impact of *[email protected]*.mers and similar ransomware threats.