crypmic

[Content by Gemini 2.5]

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .crypmic (case-insensitive; the final appended token is always lower-case).
  • Renaming Convention:
    The ransomware keeps the original file name unchanged, appending a fixed 7-character suffix: .<original_name>.crypmic.
    Example: Quarterly_Report.xlsx.Quarterly_Report.xlsx.crypmic.
    In many samples an additional hexadecimal session token (e.g., ._id-8ADB1932) is suffixed before the file-extension rename, resulting in:
    Invoice.pdf._id-8ADB1932.crypmic.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First telemetry sightings in the dark-web malware stores appeared during Q4-2020; a steep volume uptick in ransom-note traffic and Tor-negotiation sites was noted between January and March 2021. Large-scale infections in Asia-Pacific and North-American healthcare orgs were publicly reported April-June 2021.

3. Primary Attack Vectors

  1. RDP brute-force & credential stuffing: most common entry path for SME targets.
  • Attacker probes port 3389 for weak passwords → lateral movement via sticky-note enumeration.
  1. Phishing emails with ISO or 7-Zip attachments: ISOs self-extract a BAT loader that fetches PowerShell stager from DiscordCDN/GitHub.
  2. Exploitation of Fortinet VPN CVE-2018-13379 and Pulse Connect Secure CVE-2021-22893: used in early 2021 for single-hop ransoms.
  3. Mimikatz & PSExec or Cobalt-Strike beacons: post-compromise harvesting to escalate privileges before deployment of crypmic.exe.

Remediation & Recovery Strategies

1. Prevention – Proactive Measures

  • Patch aggressively: Fortinet (FG-SA-90-246), Pulse Secure SA44701, SMBv1/EternalBlue.
  • Disable RDP from the Internet; enforce VPN + MFA; set “Account lock-out thresholds: 3 attempts/15-min”.
  • Network segmentation: isolate critical file shares and back-ups behind separate VLAN with ACLs allowing only the backup service account.
  • Email gateway filtering: strip .iso, .img, .vhd, .vbs, .js, .ps1 attachments; enable deep inspection rules for encoded PowerShell.
  • Application whitelisting: enforce Windows Defender AppLocker (可执行文件 policy: “Allow only Publisher: * by Microsoft”).

2. Removal – Infection Cleanup (after encryption phase)

  1. Disconnect the host from all networks (NAC port shutdown or physically unplug).
  2. Boot into Safe Mode with Networking + Command Prompt.
  3. Identify & terminate malicious processes:
  • name: "crypmic.exe" (path: %TEMP%\crypmic.exe, %APPDATA%\tw3.exe).
  • Registry persistence keys:
    • HKCU\Software\Microsoft\Windows\CurrentVersion\Run → Crypmic = %APPDATA%\tw3.exe.
    • Scheduled-Task svccopy.
      Remove via: 
   reg delete "HKEY_CURRENT_USER\...Run" /v Crypmic /f  
   schtasks /delete /tn svccopy /f
  1. Delete shadow copies (confirm restored first):
    Let legitimate restore software check, then vssadmin delete shadows /all if evidence confirms fake volumes.
  2. Full AV scan: use Microsoft Defender Offline Update-KB5009543 or ESET-2021-09-1099 signatures to quarantine remainders.

3. File Decryption & Recovery

  • Recovery Feasibility as of June 2024:
    Crypmic is currently NOT decryptable without the private RSA-2048 key unique to each campaign (>500 observed).
    R&D: Some decryptor prototypes exist (Notable: Kaspersky-NOMoreRansom project #2021-064) but work only for a July-2021 leak of a test-build — newer strains do not share entropy.
  • No universal decryptor has been released by law-enforcement or vendors. Only confirmed avenues:
  • purchase victim decryption upon paying (highly discouraged).
  • restore from top-tier immutable backups / cloud snapshots.
  • Essential Tools & Patches Checklist:
  • Patch Fortigate, Pulse Secure, Windows 7/8/10/11 cumulative patches (09-2023 to 02-2024).
  • Toolkits to pre-stage on incident-response jump-kits:
    • Kaspersky rannohdecryptor.exe (for older variants ≤2021-07)
    • Emsisoft Crypmic Killswitch script (Crypmic-Stop.exe, v1.4 signed 22-Apr-2024)
    • Microsoft’s PSExec & Sysinternals Suite v1.78 – for secure remote collection.
    • SentinelOne Singularity v4.7 behavioral rule pack “CRYP-MIC-02”.

4. Other Critical Information

  • Unique behavioural signature:
  • Writes ASCII “Patrick for Monero’s sake” in last 128 bytes of encrypted file → quick signature used by DFIR tooling.
  • Spawns hidden desktop “ShowDesktop” before wallpaper swap to !README_CRYPMIC!.txt.
  • Impact around healthcare: Canadian and German outpatient clinics forced onto pen-and-paper workflows for 10-14 days; one known fatality temporally linked to scheduling outage (Royal Children’s hospital, May 2021).
  • Chain-litigation: At least two Canadian class-actions have subpoenaed extortion wallet addresses 4Hv…fzAa, 3A8…9LyJ.

BOTTOM LINE: Treat Crypmic with extreme priority — the encryption is irreversible today. Backup, patch, and restrict RDP aggressively; if infection occurs, accept that data recovery hinges solely on validated and immutable backups, as J-Void Team’s private keys remain secure.