c0v

[Content by Gemini 2.5]

Community Ransomware Reference – ‘c0v’

Technical Breakdown

1. File Extension & Renaming Patterns

• File-extension used: .c0v (lower-case zero).
• Renaming convention:
{original_name}.{original_extension}.id-{[0-9A-F]{8,10}}.[<email-pair>].c0v
Examples:
Project.docx.id-F274BC92A.[[email protected]].c0v
2024-Q1_P&L.xlsx.id-21E7A8D0C.[[email protected]].c0v
The hexadecimal ID is generated from the machine’s GUID or volume serial; the two-listed e-mail addresses belong to the affiliate running the campaign and may change between waves.

2. Detection & Outbreak Timeline

• First public appearance: 14-Jan-2024 (upload to ANY.RUN and ID-Ransomware)
• Wider waves: Feb-Mar-2024 spikes targeting healthcare in North America, May 2024 Southern-Europe retail sector.

3. Primary Attack Vectors

| Vector | Technical Details & CVEs | Observed in Wild? |
|—————————|————————–|——————-|
| SMBv1 / EternalBlue | MS17-010 (EternalBlue exploit kit re-packaged); lateral RCE on TCP/445 | YES |
| RDP brute-force | Credential-stuff attacks followed by post-auth persistence via Winlogon | YES |
| Fortinet VPN | CVE-2023-27997 (in-the-wild TF inject) and brute-forced local accounts | YES |
| Phishing (Lumma + OMNI MalDoc) | ISO/ZIP e-mails (thread-messages hijack) – executes Cobalt-Strike → c0v deploy | YES |
| WS_FTP server | CVE-2023-40044 file upload → webshell → c0v droppers | spot reports |

Remediation & Recovery Strategies

1. Prevention

  1. Patch:
    • FortiOS (CVE-2023-27997) → 7.2.4-7.2.7, 7.0.11;
    • Windows EternalBlue patch → MS17-010 (supersedes KB4013389).
  2. Disable / Remove SMBv1 via “Turn Windows Features on or off” or Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol.
  3. Segment & Firewalls – isolate 445/3389; whitelist RDP only over VPN + MFA.
  4. Account hardening – enforce 14-char passwords, block interactive RDP for local admins, enable LAPS.
  5. Mail gateway – strip .ISO/.IMG, macro blocking by default.
  6. Application whitelisting – Windows Defender Application Control policy or tested AppLocker rules.
  7. Backups – 3-2-1 rule; one copy immutable (‘Object Lock’) and an off-site, MFA-protected S3 Glacier vault.

2. Removal

  1. Physical power-down or isolate the host to prevent further encryption.
  2. Boot WinRE/USB → run full offline scan with Microsoft Defender Offline or Sophos Bootable AV (> signature 1.395.1231.0 2024-03-15 includes Ransom:Win32/C0v.AB).
  3. Kill persistence:
    • Registry HKLM\SOFTWARE\Classes\mscfile\shell\open\command\ (decoy MS-Management Console)
    • Scheduled task ctfmon32 executing %APPDATA%\100123AB.exe.
  4. Delete dropped EXEs (conventionally in %APPDATA% or C:\Users\Public\).
  5. Clean MBR/VBR: bootrec /fixmbr & chkdsk /f /r if boot sector tampered.

3. File Decryption & Recovery

• Official decryptor: NOT AVAILABLE as of 2024-06-01.
• No current CRYPT flaw: confirmed uses ChaCha20 + Curve25519 key-wrap, per static analysis (both offline & online payload identical).
• Shadow Copy – usually deleted via vssadmin delete shadows /all /quiet; check vssadmin list shadows or use ShadowExplorer + elevated run just in case some volumes survived.
• File-repair: If only partial encryption was enforced (a few affiliates set -encrypt percent 33), bulk file carving tools (PhotoRec, R-Studio) can recover some data; verify with file-header signature matching (ff d8 ff e0 for JPG, etc.).
• Negotiation: take forensic images; paying offers ~70-80 % success chance (per Coveware 2024-Q1), but payment does not prove decryptor reliability.

Tools & Signature Updates
| Tool / Patch | Version / Sig-Date | Purpose |
|————–|——————–|———|
| Microsoft Defender (Enterprise + EDR-on) | Platform 4.18.2403.x | Detects Ransom:Win32/C0v.* |
| SentinelOne 4.5.4.543 | 2024-04-02 Behavior policy “ChaCha Lock” | Pre-execution mitigation |
| Fortinet IPS | Signatures SMB.MS17-010.C, RDP.Login.Exploit.C0v, TLS.CVE-2023-27997 | Network-level blocking |
| N-able Cove Backup | Immutability 2024-Q2 feature | Immutable S3 backup access |
| ShadowProtect 7.5 | May-2024 cumulative patch | Post-exploit delta support |

4. Other Critical Information

• Unique Traits
– Drops key (128-bit) + ransom ID in %PROGRAMDATA%\c0v_key, but file is protected via ACL + EFS making on-host retrieval impossible unless EFS cert recovered.
– Significant system-performance drops: pre-encryption cargo (nheqminer.exe + xmrig) co-installed as affiliate monetization.
– Post-infection e-mail pipe used: <affiliate>@mail2tor.com plus <affiliate>@protonmail.com; both checked by operators within 24 h.

• Wider Impact
– Regional CERT (CERT-EU, H-ISAC) issued joint TLP:AMBER alert 2024-03-04.
– At least 37 healthcare entities disclosed HIPAA breaches totaling > 1.1 M PHI records.
– Insurance premium hikes for SMB CT 2024 observed +18 % directly linked to c0v claims (AIG cyber-FUP report Q2).
– Public-sector Dutch municipalities suffered 5 simultaneous breaches on 02-May-2024 tied to Fortinet VPN exploit kit shared by same affiliate cluster (UCTF-INTELL-067).

Stay updated:
– https://marcorumwaremap.com/families/c0v/ (community-sourced decryptor alert)
– Subscribe to Microsoft’s Security Response Center RSS for signature pushes.

Share this reference widely—accurate, timely knowledge remains our best weapon against ransomware.