drcrm

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends “.drcrm” (case-insensitive) to every encrypted file.

  • Renaming Convention: The malware keeps the original filename but adds a shrill prefix and final extension in this layout:
    <original_name>.id-<8-hex-chars>.[<attacker_email>].drcrm

    Example:
    Report_2024.xlsx → Report_2024.xlsx.id-A4F1D237.[[email protected]].drcrm

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First public sightings surfaced in February 2024; a modest spike in telemetry occurred through March–April 2024 when spam waves hit Europe and Latin America.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Phishing e-mails → Weaponised MS Office or PDF attachments that drop GuLoader, which then fetches drcrm.
  • ZIPs masquerading as invoices containing LNK files that execute PowerShell downloaders.
  • Exploitation of public-facing RDP / GPON routers with weak or leaked credentials, followed by PsExec lateral movement.
  • Seamless abuse of legitimate AnyDesk binaries (package B) embedded in the payload, giving attackers GUI access to run the encryptor manually.
  • No evidence of worm-like SMB exploits (EternalBlue) at this time – campaign remains human-operated.

Remediation & Recovery Strategies:

1. Prevention

  1. Disable Office macros by policy; only allow signed macros in trusted locations.
  2. Block outbound connections unless a proxy permits them (firewall egress filtering) – stops downloaders from reaching their payload server.
  3. Restrict RDP to VPN-only or, at minimum, enforce multi-factor authentication – neuters credential stuffing attempts.
  4. Apply vendor security updates for Windows and firmware for GPON/IoT routers to eliminate edge-of-network footholds.
  5. Maintain 3-2-1 backups: three copies, on at least two media, one offline/off-site.
  6. Segment networks so an infected workstation cannot reach critical servers.

2. Removal

  1. Isolate the host: unplug network cable / disable Wi-Fi.
  2. Boot into Safe Mode with Networking (keep Internet off unless required to fetch a removal tool).
  3. Stop malicious processes/services: Run the latest ESET Online Scanner or Trend Micro Ransomware File Decryptor with heuristics enabled; both detect all known drcrm samples.
  4. Stage clean-up via Group Policy: push taskkill /f /im anydesk.exe and delete scheduled task SystemLogonUpdate.
  5. Remove registry persistence keys:
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\drcrmService
    HKLM\SOFTWARE\Policies\Microsoft\Windows\System\Scripts\Startup\bkpcln.bat
  6. Patch any credential stuffing source: force password reset for exposed RDP/GPON accounts.

3. File Decryption & Recovery

  • Recovery Feasibility: There is no known flaw or published decryptor for drcrm as of June 2024. Cryptographically, files are encrypted with Curve25519 followed by ChaCha20; keys are wiped locally after upload.
  • Try Tools: Although Kaspersky – Trend Micro – Bitdefender – Emsisoft portals do NOT list drcrm yet, submit a ransom note and 2 sample files to NoMoreRansom.org periodically; if law enforcement seizes servers, future key releases may appear.
  • Essential Tools/Patches for Prevention:
  • Windows 10/11 cumulative updates (KB5034763 or newer) patch flaws leveraged by GuLoader.
  • AnyConnect & FortiClient patches to fortify VPN endpoints against stolen session abuse.

4. Other Critical Information

  • Additional Precautions:

  • drcrm installs a custom Chrome/Firefox extension (RdpPlugin) that steals saved credentials—so after cleanup, force-logout of all browser profiles and rotate cached online passwords.

  • Its ransom note is “HOWTOBACK_FILES.html” and features the same vos-no-id victim-ID header used by other Dharma/Phobos off-shoots, suggesting shared infrastructure.

  • Broader Impact: While still small compared with LockBit or BlackCat, drcrm’s rapid pivot towards AnyDesk abuse signals a shift from mass-spam to semi-targeted intrusions against SMEs. It joins an emerging cluster of ransomware crews that prefer RDP-to-RAT escalation followed by human-driven encryption, making credential hygiene and network segmentation the single biggest mitigation lever.