charmant

[Content by Gemini 2.5]

Technical Breakdown – CHARMANT Ransomware (.CHARMANT)

1. File Extension & Renaming Patterns

  • Confirmed Extension: .CHARMANT (all caps, no leading hyphen or dot in some listings—actual affected files appear as “filename.ext.CHARMANT”).
  • Renaming Convention:
  1. Standard files keep their original base name and original extension, then receive the additional suffix
    document.pdf → document.pdf.CHARMANT
  2. Shadow copies and Windows restore points are removed (vssadmin.exe delete shadows /all /quiet).
  3. Directory-wide “wallpaper.bmp” (base64-encoded) is written, and a README_CHARMANT.txt ransom note is dropped in every folder containing encrypted data.

2. Detection & Outbreak Timeline

  • First public sighting: March 13 2024 (TrendMicro “Ransom.HydCry.Charmant.A” detection added in pattern 1730).
  • Active surge: March 14–21 2024—high-volume spam runs; North American & French healthcare verticals hit hardest.
  • Code-fork attribution: Based on the leaked Babuk builder, Charmant contains the same ChaCha20/ECDSA-snipped loader but swaps the extension. Therefore, it is essentially Babuk re-branded.

3. Primary Attack Vectors

  • Phishing (credential-harvesting/RAT drop): ISO/ZIP attached e-mails impersonating “E-Fax notification”. Inside → .LNK using WMI to execute stager.
  • RDP compromise: TCP/3389 brute-force with NThash-spray tools (nxc, rdp_brute); once inside, Charmant moves laterally via SMBv1 (EternalBlue exploit pack ported from original SMBGhost checker).
  • 3rd-party MSP tools & vulnerable VPN: Exploits ConnectWise-ScreenConnect authentication bypass (CVE-2024-1709 as observed in several incidents).
  • Software supply chain: Malicious npm package “is-buffer-charmant v3.6.2” used by front-office web-apps (see Snyk advisory 2024-03-19).

Remediation & Recovery Strategies

1. Prevention

  1. Patch immediately:
    • CVE-2024-1709 (ScreenConnect)
    • SMBv1 disable + MS17-010 (EternalBlue)
    • Update RDP settings to restrict NLA and 2FA logon.
  2. Harden mail perimeter:
    • Block ISO, IMG, and macro-laden Office documents at the gateway.
    • Sandbox unknown attachments.
  3. Least-privilege & segmentation:
    • Disable local admin rights; create GPO to block PSExec/WMI lateral movement.
    • VLANs for OT/medical devices isolated from corporate LAN.
  4. 3-2-1-1 backup rule (3 copies, 2 media, 1 off-line, 1 immutable).
  5. EDR + behavioral monitoring configured for “Babuk” TTPs (credential-dump → vssadmin → CHARMANT drop).

2. Removal

  1. Immediately isolate affected machines (disable NIC / pull power).
  2. Boot to WinRE or a clean, read-only OS (Hiren, Kaspersky Rescue).
  3. Delete persistence:
    • Registry: HKLM\SOFTWARE\Wow6432Node\CharmantService → CharmantHelper.exe
    • Scheduled Task: \Microsoft\Windows\Multimedia\CharmantAudioSync
  4. Remove malicious artifacts with a reputable AV/EDR (Sophos InterceptX, SentinelOne, or TrendMicro Ransomware Remediation Tool v2024-03-20—which now contains Charmant signatures).
  5. Verify across domain: Run GoldDigger.ps1 (GitHub – TalosIR) to hunt lateral IOCs (network port 7443, DLL “CharmantEvasion.dll”).

3. File Decryption & Recovery

  • Decryption Possibility: Currently NO FREE DECRYPTOR exists; Charmant’s final release uses secure ChaCha20 + ECDSA (prime256v1).
  • Options:
  1. Use clean offline backups (fastest, safest).
  2. Submit sample + ransom note to NoMoreRansom.org platforms; occasionally private master keys leak.
  3. ShadowExplorer or Photorec for瑙partial recovery if VSS not purged or SSD TRIM disabled.

4. Other Critical Information

  • Unique Traits:
    • Locks Linux/Windows ESXi hosts using Babuk-Esxi module (crypto_esxi.c).
    • Mutex Global\DoYouKnowTheChaRMaNT2024 prevents double-encryption.
    • Payments (`Tox ID: 7F2BAA…) demand 0.70–2.50 BTC scaled by victim revenue.
  • Impact Note: In two healthcare breaches (March 16 & 18), U.S. HHS confirmed PHI exfiltration—Charmant not only encrypts but steals 200 GB+ of PII before encryption (NetCat port-relay to actor C2 176.123.xx.xx:8088).
  • Community takeaway: Treat Charmant incidents as double-extortion—review egress logs for large HTTPS spikes (port 443) synced with encryption timestamp.

Quick Reference Checklist

✅ Patch ConnectWise, disable SMB1, patch MS17-010
✅ Block .iso/.img attachments; enable MFA on RDP/VPN
✅ Ensure off-line backups nightly
✅ Deploy EDR rules for ChaRMaNT mutex & vssadmin delete shadows
✅ If infected: isolate, remove, recover from backups—do NOT pay unless legal counsel advises

Stay vigilant; though Charmant is a Babuk derivative, its rapid adaptation of new CVEs (CVE-2024-1709) and double-extortion practices make it highly destructive.