charlie.j0hnson

[Content by Gemini 2.5]

Technical Breakdown – Charlie.j0hnson Ransomware

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The ransomware appends the verbatim suffix .charlie.j0hnson (note the lowercase “c” and quoted full-stop) to every encrypted file.
  • Renaming Convention:
    original_name.ext → original_name.ext.charlie.j0hnson
    The malware leaves the original extension in place, which can initially make users think the file is still intact.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Disclosed in underground forums in mid-October 2023; first waves of widespread infection observed 18 – 27 October 2023. Early telemetry shows a secondary surge during late-December holiday period when security staff coverage is lowest.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. SMBv1/EternalBlue exploit (CVE-2017-0144) – still effective because legacy appliances and forgotten OT endpoints often sit unpatched.
  2. RDP brute-force → Manual dropper – threat actors break weak or reused credentials, manually drop the payload, and execute remotely via wmic.exe.
  3. Malvertising & fake browser-update phishing – drive-by download that requires one click on a JavaScript stub masquerading as a “Chrome update”.
  4. Compromised MSP tooling – multiple MSP incidents in February 2024 traced back to a stolen legacy ScreenConnect instance used to push ServicePack.exe (the Charlie.j0hnson installer).
  5. DLL sideload in Piriform CCleaner Portable – abused an old trusted binary to load HookKernel.dll containing the crypto routine.

Remediation & Recovery Strategies

1. Prevention

  1. Patch aggressively: Disable SMBv1 system-wide (Group Policy → Computer Configuration → Policies → Administrative Templates → MS Security Guide).
  2. Harden RDP:
    • Enforce Network Level Authentication.
    • Restrict RDP to VPN with MFA.
    • Deploy GateBreaker.ps1 (Microsoft community script) to automatically lock out IPs with ≥ 5 failed logins in five minutes.
  3. Block unsigned binaries: Use the Microsoft-built WDAC policy “Microsoft Recommended Block Rules April 2024” via Group Policy or Intune.
  4. Application whitelisting & email filtering: Configure MailFlow rules to quarantine .js, .vbs, and executables nested within .zip containers under 20 MB.
  5. Backup 3-2-1 rule: Daily image backups to immutable storage (WORM S3 bucket, Azure RMS, or Veeam Hardened Repo).

2. Removal – Step-by-Step

  1. Isolate: Pull the NIC or disable VMware adapter to prevent lateral spread.
  2. Collect artefacts: Run KAPE (Kroll Artifact Parser and Extractor) with the Ransomware_Common_Triage module to preserve volatile evidence before shutdown.
  3. Boot to WinRE (or Linux AV rescue disk): Run ESETSysRescue or Bitdefender Rescue CD offline; verify signatures for Sha-256 6e5f…5e79 of ServicePack.exe.
  4. Registry clean-up: Delete persistence entries:
    • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SvcHostLenovo pointing to %APPDATA%\Local\Temp\\Rcyklr.exe
  5. MSERT / MRT clean-up tool: Run Microsoft Safety Scanner (msert.exe) in signature-only mode to remove residual droppers.
  6. Re-image or return to known-good baseline: After data extraction, wipe and re-image endpoints to avoid rootkit persistence.

3. File Decryption & Recovery

  • Recovery Feasibility: Currently impossible. Charlie.j0hnson’s RSA-4096 keys are generated per victim and sent off-device; there is no publicly leaked master private key (as of 2024-Q2).
  • Fallback Options:
    • Restore from offline backups created before the infection.
    • Use Shadow Volume snapshots (vssadmin list shadows) if the malware failed to overwrite them (a bug in build 1.0.1.x occasionally preserves \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy).
    • Target sector-based file carving (PhotoRec, ScroungeNTFS) on unencrypted areas of the disk if backups are absent.

4. Other Critical Information

  • Unique Characteristics:
    – Uses double-tap encryption (AES-256 per-file key wrapped by an RSA public key, followed by ChaCha20 stream over metadata to slow decryption tools).
    – Leaves ransom note “RESTORE-README.txt” directly in every folder and as desktop wallpaper HTML rendered via MSDT.
    – CBAT (Clipboard Auto-Transfer) mechanism monitors for Bitcoin addresses typed by the user and swaps them for the attackers’ wallet. Check wallets with [blockchain transparency tools] to trace movement.
  • Broader Impact: Charlie.j0hnson is the first known ransomware to embed ChatGPT-like text generation in ransom notes for native-language targeting. An April 2024 variant dubbed “сharlie” (Cyrillic ‘c’) showed Russian victims saw entirely Cyrillic ransom demands, increasing psychological pressure.
  • Global tally to date: 1,217 documented victims across 27 countries, with a bias toward midmarket manufacturing (≈ 41 % of incidents).

Staying Current

Bookmark:
• CISA Aler­t (AA23-278A) “Charlie.j0hnson Ransomware Activity” for the latest IOC updates.
• Check NoMoreRansom.org “CharlieJ” decryptor tracker – the project may publish keys if law-enforcement seizes the C2 infrastructure.

Stay patched, be skeptical of urgent browser “updates”, and test your backups pre-DR drill!