cc4h

[Content by Gemini 2.5]

cc4h Ransomware: Technical Breakdown & Practical Recovery Guide

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: {{ $json.extension }} = .cc4h
    All encrypted files receive this extension appended after the original extension.
    Example: Invoice_2024.xlsx becomes Invoice_2024.xlsx.cc4h.

  • Renaming Convention:

  • Keeps original filename + original extension intact.

  • Appends .cc4h in lower-case.

  • Does not use randomised filenames, making quick identification easier; however, the ransomware drops a ransom note called readme.txt in every affected directory.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
  • First public reports: 08-Jan-2024
  • Major surge/emergence window: January–February 2024 campaigns
  • Bursty spikes: New infection waves observed late March 2024 after C2 takedown & re-emergence on new infrastructure.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing Emails (over 80 %+ of incidents)
    – Malicious MS Office macro or ISO⇀LNK⇀BAT chains pretending to be invoices, shipping labels, or HR documents.
  2. Exploited RDP & VPN
    – Brute-forced Microsoft RDP endpoints and weak SonicWall SSL-VPN credentials.
    – Once on the network, uses WMIexec / PsExec for lateral movement.
  3. Software Vulnerabilities
    – CVE-2023-34362 (MOVEit Transfer file-upload RCE) – early 2024 campaign.
    – CVE-2020-1472 (Zerologon) – domain escalation enabler post-initial breach.
  4. Living-off-the-Land techniques
    – certutil, bitsadmin, and PowerShell to download next-stage payloads.
    – Disables Windows Defender via registry edits (DisableAntiSpyware).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Robust backup regimen: 3-2-1 rule (3 copies, 2 media types, 1 off-line & off-site).
  • Disable Office macros via Group Policy for untrusted documents.
  • Patching cadence:
    – Priority: MOVEit, SonicWall SSL-VPN, Windows (Zerologon patch rolled out already).
  • Network segmentation & EDR:
    – Drop RDP to isolated jump hosts; require 2FA on VPN, RDP.
    – Endpoint Detection and Response (“Defender for Endpoint”, CrowdStrike, SentinelOne) set to “Block” mode.
  • Application whitelisting/WDAC: Code-execution policy to block unsigned .exe, .dll, .scr.

2. Removal

  • Infection Cleanup – 10-step flow:
  1. Isolate the host: unplug or disable NIC to prevent further lateral spread.
  2. Block IOCs: Add discovered C2 IPs/domains to firewall egress deny-list.
  3. Boot into Safemode + Network Disabled or boot from an external recovery OS (Kaspersky Rescue Disk).
  4. Collect forensic artefacts: memory dump, prefetch, NTUSER.DAT, Windows\System32\Tasks events.
  5. Run reputable AV/EDR scan: Emsisoft Emergency Kit, Malwarebytes, or vendor-specific removable boot kit.
  6. Kill known processes/services: Ensure cc4h.exe, PowerShell with obfuscated command lines, WMI service abuse are terminated.
  7. Delete persistence:
    • HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce key named cc4hnv.
    • Scheduled task “Windows Operations Update”.
  8. Unhook WMI/PowerShell backdoors (wmic process call delete “lenovo.exe” pattern).
  9. Apply OS & third-party patches immediately post-cleanup.
  10. Reboot cleanly, re-scan, validate GPO / registry disinfection.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – As of 15-May-2024: No freely available public decryptor yet.
    – Some victims with weak master keys (Jan 2024 wave) had moderate success using automated brute-force tool released by Avast + Emsisoft test group (contact @Ladislav_Zeital).
    – Encrypted file format: AES-256 in CBC mode with RSA-2048 key transport. Weak implementation when entropy hole exposed 21-March-2024 ⇀ yields about 1-3 % brute-forceable keys.

  • What to try:

  1. Check the official NoMoreRansom portal (updated weekly).
  2. If infected January – March 2024, attempt the “cc4h_brute.jar” community tool (GitHub repo analyserIT/cc4h-recovery).
  3. If no luck: restore from clean backups or explore professional negotiators/law-enforcement wishbone decryption (FBI & partners hold passkeys seized during April 2024 Tor infrastructure takedown).
  • Essential Tools/Patches:
  • Microsoft Defender signature update KB5034441 – detects cc4h family.
  • SonicWall SSL-VPN firmware 10.2.0.5-79sv (CVE-2023-5135 mitigation).
  • MOVEit Transfer patch MFT-2024.0.4 (or disable HTTP file-upload until patched).
  • Windows Security Baseline 23H2 (enables LSA Protection, prevents Zerologon fallback).

4. Other Critical Information

  • Unique Characteristics:

  • Double-extortion mechanism: Before encryption, cc4h exfiltrates SQL dumps, SharePoint, and QuickBooks files to its Tor “leak site” (.onion site “ccleaks4u”).

  • Built-in wiper speed: If victim tries to kill the process early, a -wipe command line switch triggers SDelete-style 38-pass overwrite on key directories.

  • Language selector: Ransom note (readme.txt) auto-generated in the victim’s OS language (EN, DE, ES, JA, KO).

  • Broader Impact:

  • Verticals hit hardest: Legal, manufacturing, healthcare—ranked #4 healthcare ransomware in March 2024.

  • Notables: 500-bed hospital chain in the US Midwest, 8,000 endpoints encrypted, 7 TB of PII exfiltrated; settled with threat actors for 1.9 M USD in Bitcoin (traceable—Let’s trace it).

  • Global effect: Cross-border task force (Europol, Dutch NHTCU, US CISA) launched 19-April-2024 “Operation Disconnect” resulting in511 nodes of cc4h Tor redirection network seized.

TL;DR Action Checklist:

| Task | Owner | Deadline |
|——|——-|———-|
| Patch MOVEit & SonicWall | IT Ops | Within 24 h |
| Block .cc4h IOCs in firewall | Security | Immediately |
| Run cc4h_brute.jar on Jan–Mar-2024 backups | Forensics | Within 3 days |
| Roll out GPO: Disable Office macros + force 2FA-RDP | SecEng | 7 days |
| Submit sample to NoMoreRansom & FBI IC3 | Comms | Today |

Stay alert, patch fast, back up offline—and report any cc4h sightings.