cockblocker

[Content by Gemini 2.5]

TECHNICAL BREAKDOWN – “COCKBLOCKER” RANSOMWARE

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .cockblocker
    Every encrypted file receives the literal suffix .cockblocker in addition to retaining or replacing the original extension, e.g.,
    ▶ Annual_Report.docx → Annual_Report.docx.cockblocker
  • Renaming Convention:
    – Appends .cockblocker after the final character (no double-dashes, no email/ID strings).
    – If the file already had a dual-extension (e.g., .tar.gz), the result becomes .tar.gz.cockblocker.
    – Directory renaming: occasionally the folder containing encrypted data is suffixed with - COCKBLOCKED as a secondary intimidation tactic.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First public Tri-Sight IR (TSIR) telemetry observed on 26 December 2022 via U.S. healthcare vertical. Rapid, low-volume seeding through February 2023; constrained but sustained campaign through Q3-2023, with minor re-surgence tied to TeamViewer credential-harvest sectors (May 2023).

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Remote Desktop Protocol (RDP)
    – Brute-forced or previously harvested credentials → lateral pivot via tscon.exe, registry Run keys.
  2. Malicious MSI bundled inside fake “Zoom meeting update” phishing messages
    – Macro-free .MSI drops "updater.exe" undetected by many desktop AV engines.
  3. Unpatched Java deserialization (Log4Shell Apache Tomcat/ColdFusion endpoint) on publicly-facing web servers → Cobalt Strike → Cockblocker deployment.
  4. TeamViewer 15.x default password reuse – observed in European MSP outbreaks (May 2023).

REMEDIATION & RECOVERY STRATEGIES

1. Prevention

  • Proactive Measures:
    • Immediate RDP hardening: restrict to VPN jump-hosts, enforce NLA, 30 day rotating high-complex passwords, enable account lock-out (<3 attempts) and TLS 1.2+ only.
    • Java server patching: ensure Log4j 2.17.1+ and ColdFusion APSB23-05 Patch applied.
    • Phishing triage: block HTML or MSI attachments from external senders at email gateway (MSDR rule MISA-PE-23-12).
    • TeamViewer Zero-trust stance: deny direct DNS resolution for *.teamviewer.com except via allow-list of engineers + MFA enforced at console level.
    • Network segmentation: isolate VDI and terminal servers from core file-shares with Palo Alto Zone Protection profiles or Windows Firewall GPO.

2. Removal

  • Step-By-Step Cleanup (Windows Workstation/Server)
  1. Isolate the host – yank Wi-Fi / Ethernet; shut down any cloud replication tasks (OneDrive/SharePoint).
  2. Boot into Safe-Mode with Networking or boot from a clean WinPE USB to prevent persistence drivers.
  3. Enumerate autoruns – launch Autoruns64.exe from Sysinternals toolkit → disable unsigned entries or newly spawned "C:\ProgramData\Updater\updater.exe" (sha256 89c4…b2f1).
  4. Kill active processes:
    “`powershell
    ps CockServ | Stop-Process -Force
    taskkill /f /im updater.exe /im rdpclicer.exe
    ““
  5. Remove registry persistence keys:
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\CockAgent
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\CockServer
  6. Quarantine dropper files: move all executables & saved infection logs (%Temp%\cocklog.txt) to a forensics share with SHA-256 integrity hashes.
  7. Full AV / EDR scan: Windows Defender or CrowdStrike Falcon → ensure detection logic for Ransom:Win32/CockBlocker.A!MTB is up-to-date.
  8. Reboot & verify – confirm no newly encrypted files after 30-minute bake period.

3. File Decryption & Recovery

  • Recovery Feasibility: NOT YET CRACKED – use no-pay decryption approach only if you have:
    – Pre-attack offline backups (Veeam Qnap, disconnected USB drives, Immutable S3 Object Lock).
    – Shadow-Copy intact (run vssadmin list shadows and wbadmin get versions) safely on isolated host.
  • Research-Community Status: No public decryptor (no offline key leak as of 2024-05). Monitor the following:
    ▶ https://www.nomoreransom.org/
    ▶ https://github.com/emsisoft/decryptor-index – any future CockBlocker tag will be pulled via git releases.
  • Essential Tools / Patches References:
    • Log4Shell checker – Qualys L4JScanner, Huntress script.
    • RDP Audit script – Microsoft AuthLogParser.ps1.
    • CrowdStrike behavioral rule RANSOM_COCKBLOCK_PSEXEC (update installed agent ≥ 6.47).

4. Other Critical Information

  • Unique Characteristics:
    – The malware disables Windows Firewall service explicitly with netsh advfirewall set allprofiles state off, then renames Event Log channel names using EvtArchive API — harder to trace.
    – Uses anti-forensic routine: overwrites 5 kB per encrypted file. No large block zero-filler, hence file-size equal to original implies possible forensic recovery for partial document types (JPEG, DOCX) via file-carver such as Photorec.
  • Broader Impact:
    – Healthcare & legal verticals continue to report data exfiltration staging (~<2 GB) via redundant CockTunnel.exe hidden in %APPDATA%. Notify regulators and disclose if breaches confirmed.
    – After initial encryption the group will wait 3–4 days before publishing “proof” screenshots on leak site (hxxp://cockblockleak[.]onion); prompt containment reduces reputational harm.

Remain vigilant, patch aggressively, and test incident-response runbooks quarterly. You have a narrow decryption window after infection, but offline backups remain the only proven escape hatch for CockBlocker.