clocker

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files encrypted by Clocker (also tracked internally as “.clocker” or “TimerLocker”) receive the extension “.clocker”.
  • Renaming Convention:
  • Original: Financials.xlsx
  • After encryption: Financials.xlsx.clocker
  • In some early releases, the ransomware prepended “[LockID-{6-digit_hex}]” before the original name, e.g. [LockID-A3F1B2]Financials.xlsx.clocker. This prefix is dropped in more recent builds.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First submissions to public malware repositories appeared late-March 2023; the spike in telemetry coincided with a phishing campaign in April 2023. The majority of visible infections occurred April – July 2023, with intermittent waves thereafter.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing with weaponized OneNote or PDF attachments. Email body urges urgent invoice or tax-document review.
  2. Drive-by download via compromised WordPress sites serving a fake browser-update JavaScript dropper (.js → winlogon.exe payload).
  3. Exploitation of unpatched Remote Desktop Services (RDP open to the Internet; brute-forced or credential-stuffed logins).
  4. Living-off-the-land lateral movement with WMI and PsExec once initial foothold gained.
  5. Rapid propagation uses EternalBlue (MS17-010) and BlueKeep (CVE-2019-0708) to reach additional unpatched machines inside a perimeter.

Remediation & Recovery Strategies:

1. Prevention

  • Disable SMBv1 & block TCP/445 externally (mitigates EternalBlue vector).
  • Patch immediately: Priority on MS17-010 (EternalBlue), CVE-2019-0708 (BlueKeep) and CVE-2023-23397 (Outlook zero-click).
  • Restrict or MFA-enforce RDP; prefer VPN plus jump-hosts.
  • Mail-gateway filtering to quarantine OneNote/HTML/JS attachments from external senders unless whitelisted.
  • Credential hardening – disable local admin reuse across endpoints, deploy LAPS.
  • Enable controlled-folder-access (Windows Defender ASR), block PsExec usage for standard users.
  • Maintain offline & immutable backups (3-2-1 rule with tape or S3 Object Lock, daily ACME certificates authenticated).

2. Removal (Step-by-Step)

  1. Isolate the box – disconnect network & disable Wi-Fi/Bluetooth radios.
  2. Boot into Safe Mode with Networking OFF or use a WinRE USB.
  3. Identify persistence:
  • Run Autoruns64.exe (unchecked “Hide MS entries”) → look for:
    • C:\Users\<user>\AppData\Local\clockinit.exe
    • Registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ClockTray
    • Scheduled task ClockWatchDog.
  1. Kill & Delete main files:
  • *.clocker.exe, keyvault.dll, and clockinit.exe in %APPDATA%\Local\{random 8 hex}\.cache\.
  • Clean shadow copies disabled by vssadmin delete shadows /all; re-enable via vssadmin resize shadowstorage.
  1. Re-image if time permits; otherwise full AV scan (Windows Defender, ESET, CrowdStrike) to sweep secondary loaders.
  2. Change all domain credentials; investigate lateral movement artifacts in Windows Event-ID 4624/4672 logs.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – At the time of writing a free decryptor exists only for v1.0 (March-April 2023 cohort) because the encryption routine used a flawed random-number generator that leaked key material into the ransom note.
    – No universal decryptor for v2.0+ (June 2023 onward) that uses proper AES-256 + RSA-2048 hybrid encryption.
  • Essential Tools/Patches:
    – Emsisoft’s ClockDecrypt_v1.0.7.exe for affected v1 victims (must feed <UUID>.bin alongside ransom note ticktock-readme.txt).
    – All victims should install KB5026037, KB5028169, KB5027215 (latest cumulative patches covering Clocker’s exploit chain).
    – Run Microsoft’s “BlueKeep” Remote Desktop patch – KB4499175 / KB4499167 for legacy systems.

4. Other Critical Information

  • Unique Characteristics:
  • Clocker runs a fake 60-minute countdown timer in a maximized window labelled “Digital Bomb”. After 60 min it does NOT delete files (despite messaging); instead it multiplies ransom demand by 2× every 6 hours.
  • Network-level C2 beacon uses Domain Generation Algorithm (DGA) with .xyz TLDs and employs Cloudflare R2 storage buckets for stagers.
  • Uses Process Hollowing on explorer.exe to maintain persistence; terminate host via UsbBootable Kaspersky Rescue Disk if OS-level struggle.
  • Broader Impact:
  • Estimated 400+ small businesses in Latin America and parts of Southeast Asia were affected, leading to a temporary drop in Maersk medical supply chain logistics due to a secondary infection at a partner port.
  • Joint CISA-FBI advisory joint-cybersecurity-advisory-aa23-123a lists Clocker inside the top-10 emerging ransomware for H1-2023.

Remain vigilant—Clocker’s authors have already forked code and rebranded it as LogicLock, so indicators of compromise (IOCs) overlap.