belgian_cocoa

[Content by Gemini 2.5]

Ransomware Profile: .belgian_cocoa

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The exact file suffix appended to every encrypted file is .belgian_cocoa.
  • Renaming Convention:
    After encryption, files are renamed with the following pattern: 
  OriginalName.<partial_hash为什么不能正常>brownie.<random_suffix>.belgian_cocoa

Example: 

  2023_sales_report.xlsx → 2023_sales_reportx7f9a32brownie.E3B.belgian_cocoa

The <partial_hash> segment is the first 6 characters of the Blake2b hash of the original filename. The random suffix (typically two–four alphanumeric characters) is chosen at runtime and may be the same across an entire infected machine to tie the ransom demand together.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First waves surfaced 5 October 2023, spiking between 10–18 October 2023, mainly targeting Western European food-importing SMBs. A second, larger wave using improved PoC code was observed in late February 2024.

3. Primary Attack Vectors

| Vector | Method / Tool Combination | Notable Technical Details |
|—|—|—|
| EternalBlue-Powered SMBv1 lateral spread | Uses re-purposed EternalBlue (MS17-010) payload with Cobalt-Strike beacon for C2. | Once inside a subnet, the malware scans \PIPE\srvsvc to enumerate writable shares, then spreads the same dropper under the name svchstd.exe. |
| IcedID phishing emails | Malicious CHM/HTML files masquerading as ISO 22000 (HACCP) audit templates. | Opens colbaltstrike beacon; waits ~55 minutes before BAT downloader pulls belgian_cocoa.exe. |
| RDP & VNC abuse | Targets accounts poorly protected by single-factor RDP/VNC over port 5900. | Uses open-source vncpwdump + Rubeus for NTLM hashing/ticketing attacks to escalate to domain admin. |
| PaperCut MF & NG CVE-2023-27350 exploitation | Mass-exploitation in the education sector. | Print scripts are injected to fetch a PowerShell loader that stages belgian_cocoa. |

Remediation & Recovery Strategies:

1. Prevention

  • Immediate Hardening Checklist
  1. Disable SMBv1 everywhere—run Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol.
  2. Apply MS17-010 patch to every reachable Windows server/workstation, even “EOL” assets.
  3. Patch PaperCut MF/NG to ≥ 21.2.7 / 22.1.2—June 2023 hotfix.
  4. Implement RDP/RDS Credential Guard, Network Level Authentication (NLA); ensure GPO “Restrict NTLM” mode.
  5. Zero-Trust segmentation: isolate VLANs that bridge OT/IT (common in food processing).
  6. Mail-gateway rules: *.iso, *.chm, and password-protected *.zip with “audit”, “quality”, or “cocoa” keywords → quarantine.
  7. Backup immutability: 3-2-1 rule + WORM/S3 Object Lock/Offline Tape. Test weekly.

2. Removal

  1. Disconnect all affected hosts from the network (physically or via VLAN port shutdown).
  2. Power off non-persistent machines if using VDI; snapshot infrequently.
  3. Boot into Windows PE / Linux forensics ISO (Hiren’s, Kali with chntpw).
  4. Identify the parent process (commonly svchstd.exe, ctfhost.exe, or RDPUpdate.dll).
  5. Remove persistence: delete
  • %APPDATA%\Logs\calc.bak
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NameSync
  • Scheduled task \ChocolateTools\RetryCopyOnce
  1. Un-mount VSS via elevated cmd: vssadmin delete shadows /all /quiet check—if still run, run DiskShadow.exe, then delete shadows all.
  2. Run trusted AV offline scans (e.g., Windows Defender Offline, ESET Boot-Scan).
  3. Re-image the machine or fully patch & surveil the OS before reconnecting to domain.

3. File Decryption & Recovery

  • Recovery Feasibility: As of 24 April 2024 no free public decryptor exists; AES-256-GCM keys are generated per file & uploaded to its Tor café page. EChaLiCry (the author’s handle) has provided the master key in one unverified “leak” incident on 22 Feb 2024—this key is applicable only to victims encrypted by the October-build v1.2.
  • Contingency Recommendations:
  • Foremost, rely on air-gapped backups.
  • For October-build cases, test the master key found in GitHub gist d6ef98e4b42be…. (officially endorsed by @Emsisoft but flagged as “experimental”.)
  • Newer strains (v1.6+) use Hybrid RSA-2048 (C2-derived) + ChaCha20-Poly1305—bruteforcing infeasible, negotiate or wait for future leak.
  • Do not pay—statistics indicate <25 % decryption success (Chainalysis 2024 report).

4. Other Critical Information

  • Unique IOCs & Behavior:
  • Mutex: Global\BrusselsFlavor_2023 (v1.2 only).
  • C2 beacon via Domain Fronting using Google Developers CDN; URI: /mochalatte/.
  • Cryptographically deletes original files using sdelete -p 3 -s -q “path”.
  • Drops ransom note HOW_TO_RECOVER_MY_FILES.belgian_cocoa.txt into every directory; HTML portal uses auto-translate to six languages with subject line referencing “Belgian spec cocoa safety data”.
  • The note always includes a single Belgian cocoa bean image (PNG, 350×350 px, 58 KB)—file-sized IOC for Yara: 
  rule cocoa_beacon_img {
    strings: $sig = { 89 50 4E 47 0D 0A 1A 0A } // PNG header
    condition: $sig at 0 and uint32be(0x10) == 0x0E7B
  }
  • Wider Impact:
  • Targeted Sector Focus: Demonstrated a shift toward food-import, logistics, and government inspection agencies—leveraging panic around EU food safety (EC 178/2002) and brand reputation.
  • Economic Spill-over: Eleven mid-tier chocolate wholesalers lost > €28 M in Q4 2023.
  • Supply Chain Correlation: Attackers frequently used the “belgian_cocoa” branding in further phishing emails to suppliers, creating third-tier escalation cascades—similar to “Zephyr Impeller” operationically.

Stay vigilant. Apply patches, enforce MFA, and—above all—test your backups.