*[email protected]*.china

[Content by Gemini 2.5]

The ransomware variant identified by the file extension *[email protected]*.china is a specific iteration or campaign associated with the Dharma ransomware family (also known as CrySiS or Phobos, though Phobos is a distinct evolution often sharing characteristics with Dharma). Dharma is a persistent and evolving threat that has plagued individuals and organizations for years. The [email protected] string is a unique identifier used by the attackers for communication, typically found within the ransom note and the appended file extension.

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by this variant will have the original filename appended with a unique ID, followed by the email address and then .china. The exact format typically follows:
    .[ID][email protected]
    For example, a file named document.docx might be renamed to document.docx.id-XXXXXXXX.[[email protected]].china or document.docx.id-[8-random-chars].[[email protected]].china. The ID often consists of 8 hexadecimal characters.
  • Renaming Convention: The typical renaming pattern is [OriginalFilename].[OriginalExtension].id-[8_HEX_CHARS].[[email protected]].china.
    • Example: photo.jpg becomes photo.jpg.id-A1B2C3D4.[[email protected]].china
    • Example: report.pdf becomes report.pdf.id-E5F6G7H8.[[email protected]].china
      Along with the encrypted files, a ransom note (usually INFO.hta or FILES ENCRYPTED.txt) will be created in directories containing encrypted files.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The Dharma ransomware family first emerged around late 2016 / early 2017. Specific email extensions like [email protected] indicate a particular campaign or set of operators. While the exact start date for this specific email cannot be pinpointed without specific threat intelligence reports, it would fall within Dharma’s continuous activity, which has persisted throughout 2019, 2020, and into current times, with new contact emails appearing regularly. This indicates a relatively recent or ongoing campaign leveraging the Dharma codebase.

3. Primary Attack Vectors

Dharma ransomware, including variants like *[email protected]*.china, primarily relies on the following propagation mechanisms:

  • Remote Desktop Protocol (RDP) Exploitation: This is the most common and significant vector. Attackers scan for publicly exposed RDP ports, then attempt to gain access through:
    • Brute-force attacks: Guessing weak or common passwords.
    • Credential stuffing: Using leaked credentials obtained from other breaches.
    • Exploitation of vulnerabilities: Although less common for Dharma itself, an unpatched RDP vulnerability (like BlueKeep, CVE-2019-0708) could be used for initial access, followed by manual deployment of the ransomware.
  • Phishing Campaigns:
    • Malicious Attachments: Emails containing seemingly legitimate documents (e.g., invoices, reports) that, when opened, execute malicious macros or exploit software vulnerabilities to download and install the ransomware.
    • Malicious Links: Links disguised as legitimate services that lead to drive-by downloads or credential harvesting sites, which then facilitate ransomware deployment.
  • Software Vulnerabilities: While RDP is paramount, other vulnerabilities in publicly facing services (e.g., unpatched VPNs, web servers, content management systems) can be exploited for initial network access.
  • Compromised Software/Cracked Applications: Malicious actors may embed ransomware within pirated software, key generators, or other “cracked” applications, which users unknowingly download and execute.
  • Supply Chain Attacks: Although less frequent for commodity ransomware like Dharma, compromise of legitimate software update mechanisms or vendor systems could lead to widespread infection.

Remediation & Recovery Strategies:

1. Prevention

Proactive measures are crucial to defend against *[email protected]*.china and similar ransomware:

  • Robust Backup Strategy: Implement a “3-2-1” backup rule (3 copies of data, on 2 different media, with 1 copy offsite/offline/immutable). Regularly test backups to ensure recoverability. Offline or immutable backups are critical to prevent ransomware from encrypting them.
  • Secure RDP:
    • Disable RDP entirely if not strictly necessary.
    • If RDP is required, restrict access to specific IP addresses via firewall rules.
    • Use strong, unique passwords for all user accounts, especially those with RDP access.
    • Enable Multi-Factor Authentication (MFA) for RDP and all critical services.
    • Place RDP behind a VPN.
    • Monitor RDP logs for unusual activity or failed login attempts.
  • Patch Management: Regularly update operating systems, software, and firmware. Prioritize security patches for known vulnerabilities, especially those affecting publicly accessible services.
  • Endpoint Security: Deploy and maintain up-to-date Antivirus (AV) and Endpoint Detection and Response (EDR) solutions on all endpoints and servers. Ensure real-time protection is active.
  • Network Segmentation: Divide your network into isolated segments to limit lateral movement in case of a breach.
  • Email Security: Implement robust spam filters, email gateway security, and DMARC/SPF/DKIM to prevent phishing emails from reaching users. Conduct regular security awareness training for employees, focusing on recognizing phishing attempts and malicious attachments.
  • Least Privilege: Grant users and applications only the minimum necessary permissions to perform their tasks.
  • Disable SMBv1: Ensure SMBv1 is disabled on all systems, as it is an outdated and vulnerable protocol often targeted by ransomware for lateral movement.

2. Removal

If an infection occurs, swift and methodical removal is essential:

  • Isolate Infected Systems: Immediately disconnect affected computers and servers from the network (unplug Ethernet cables, disable Wi-Fi). This prevents the ransomware from spreading further and encrypting more files.
  • Identify and Terminate Malicious Processes: Use Task Manager or a process explorer tool (e.g., Sysinternals Process Explorer) to identify suspicious processes. Dharma often disguises itself as legitimate system processes. Terminate them.
  • Remove Persistence Mechanisms: Ransomware often establishes persistence to restart after a reboot. Check and remove entries from:
    • Windows Registry (e.g., HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run)
    • Startup folders (%APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup)
    • Scheduled Tasks (schtasks.exe)
  • Full System Scan: Boot the infected system into Safe Mode with Networking (if necessary to download tools) and perform a comprehensive scan with a reputable, up-to-date antivirus/anti-malware suite (e.g., Malwarebytes, Windows Defender Offline).
  • Delete Ransomware Files: After the scan, ensure all identified ransomware components and droppers are quarantined or permanently deleted.
  • Change Credentials: Assume all local and domain credentials on the compromised system are compromised. Change all passwords, especially for administrative accounts, RDP accounts, and network shares. Consider a full password reset across the organization if domain controllers were involved.
  • Examine Logs: Review system logs (Event Viewer) for suspicious activities, failed login attempts, or unusual process executions that could indicate the initial point of compromise.

3. File Decryption & Recovery

  • Recovery Feasibility: For *[email protected]*.china and most other recent Dharma variants, decryption without the attacker’s private key is generally NOT possible. While some older Dharma variants had vulnerabilities that led to public decryptors (e.g., by Emsisoft, Kaspersky), these are specific to certain keys or campaigns. The continuous evolution of Dharma means that new variants like this one are highly unlikely to be decryptable by public tools. Paying the ransom is strongly discouraged as it funds criminal activity, does not guarantee decryption, and your data may still be compromised or not fully recovered.
  • Recovery Methods:
    1. Restore from Backups (Primary Method): This is the most reliable method. Use your pre-infection, offline, or immutable backups to restore your encrypted data.
    2. Shadow Volume Copies (Limited Success): Ransomware often attempts to delete Shadow Volume Copies using commands like vssadmin delete shadows /all /quiet. However, sometimes this command fails or only partially succeeds. It’s worth attempting to restore previous versions of files or folders via Windows File History or System Restore Points, though success is usually low.
    3. Data Recovery Tools (Last Resort, Low Success): In very rare cases, if the encryption process was interrupted or flawed, some fragments might be recoverable using data recovery software, but this is highly unreliable for encrypted files.
  • Essential Tools/Patches:
    • For Prevention:
      • Robust Antivirus/EDR solutions (e.g., CrowdStrike, SentinelOne, Microsoft Defender for Endpoint).
      • Patch Management Software (e.g., WSUS, SCCM, third-party patching tools).
      • Firewall (hardware/software) with granular rules.
      • Backup solutions (e.g., Veeam, Acronis, cloud backup services).
      • VPN and MFA solutions.
    • For Remediation:
      • Reputable anti-malware scanners (e.g., Malwarebytes, Emsisoft Emergency Kit).
      • Process analysis tools (Sysinternals Suite).
      • Forensic tools for incident response.

4. Other Critical Information

  • Additional Precautions:
    • Ransom Note Consistency: Like other Dharma variants, *[email protected]*.china typically leaves ransom notes (INFO.hta or FILES ENCRYPTED.txt) in every folder containing encrypted files. These notes provide instructions and contact information (the [email protected] email address).
    • Deletion of Shadow Copies: A common characteristic is the attempt to delete all Shadow Volume Copies, making native Windows file recovery difficult.
    • System Enumeration: Before encryption, Dharma often performs reconnaissance to identify network shares and connected drives to maximize its destructive impact.
    • No Public Decryptor: As of current knowledge, there is no public decryptor available for this specific *[email protected]*.china variant, reinforcing the need for robust backups.
  • Broader Impact:
    • Data Loss: Permanent loss of encrypted data if no backups are available and decryption is impossible.
    • Operational Downtime: Significant disruption to business operations, leading to lost productivity and revenue.
    • Financial Costs: Ransoms demanded can range from hundreds to thousands of dollars in cryptocurrency. Additionally, there are substantial costs associated with incident response, forensic analysis, system rebuilds, and reputational damage.
    • Reputational Damage: For organizations, an infection can erode customer and partner trust.
    • Supply Chain Risk: If a vendor or partner is infected, it can indirectly impact interconnected businesses.

Combating *[email protected]*.china effectively hinges on a strong defense-in-depth strategy, robust preventative measures, and well-tested, isolated backups.