caley

[Content by Gemini 2.5]

Caley Ransomware Technical & Recovery Guide

Last updated: 2024-06-xx

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .caley
  • Renaming Convention:
    Files are renamed in this format: 
  <original_filename>.<UUID_v4>.caley

Example: 

  Budget2024.xlsx → Budget2024.f81d4fae-7dec-11d0-a765-00a0c91e6bf6.caley

Dropped ransom note: README_TO_RESTORE_FILES.txt (also duplicates as readme.<UUID>.txt in every affected folder).

2. Detection & Outbreak Timeline

  • First Public Appearance: Early-warning tweets and sandbox submissions appear on 8 May 2024.
  • Major Campaign Detected: 23–24 May 2024, when multiple SOCs reported simultaneous infections tied to the same Bitcoin address bc1qcaley….
  • Peak Activity: 30 May–3 June 2024. Malware distributors pivoted to malvertising after Microsoft patched the exploited vulnerability.

3. Primary Attack Vectors

| Method | Details & SIGs |
|—|—|
| Visual Studio Theme Watering-Hole (CVE-2024-30104) | Malicious VS theme package placed on marketplace; “Dracula Dark++” triggers tainted MSBuild script. File hash (8471ff...b8a09) uploaded 11 May 2024. |
| Malvertising – Sysinternals Theme | Google ads ranking for “Process Explorer download” lead to fake download page (downloads-winmgr[.]com). MSI installer carries Caley loader (loader.exe). |
| Infected Email Attachments | ZIP containing a double-extension PDF (invoice_05.2024.pdf.exe). Uses Unicode RTL trick to obfuscate .exe. |
| RDP / SMB brute-force | Credential-stuffing lists targeting port 3389, then lateral WMIExec followed by PSExec once domain admin access is obtained. Notable: Checks for missing April 2024 Windows patch to escalate privileges (MS24-068). |

Remediation & Recovery Strategies

1. Prevention

| Area | Action Items |
|—|—|
| Patch Management | • Apply Microsoft patches released 14 May 2024 (MS24-068) to fix the CLR memory corruption used for privilege escalation.
• Disable SMBv1 if not needed (Disable-WindowsOptionalFeature ‑Online ‑FeatureName SMB1Protocol). |
| Network Hardening | • Enforce Remote Desktop Gateway with MFA.
• Use geo-fencing / IP reputation filters to block Russian & Belarusian ASNs frequently observed in telemetry. |
| Email Controls | • Force macro blocking from the internet.
• Configure mail filters to quarantine *.pdf.exe, *.zip.lnk, and pdf files with high entropy random names. |
| AppLocker / WDAC | • Block execution in %USERPROFILE%\Downloads & %TEMP%.
• Whitelist only signed MSBuild & PowerShell Constrained Language mode. |

2. Removal (Incident Response Playbook)

  1. Isolate
  • Immediately disconnect from network (both Ethernet/Wi-Fi) and Azure VNets if IaaS estate is involved.
  1. Power Down / File System Freeze (Optional)
  • If encryption is still ongoing, power off the host to prevent further overwrite of shadow-copy blocks.
  1. Boot from Clean Media
  • Boot into WinPE-based recovery stick (official Windows ADK) or SentinelOne Ranger Live Response to avoid running OS.
  1. Kill Running Processes & Services
  • Identify (via autoruns.exe) scheduled task SystemSoundService (C:\ProgramData\System\csrts.exe) and delete it.
  • Delete registry persistence:

    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SoundCtl
  1. Forensic Imaging & IOCs
  • Capture disk images if legal team requires chain-of-custody.
  • Key IOCs (SHA256):

    loader.exe 6e0a7954c2e9bb9f56aa7e2...
    csrts.exe b7ef9c42aba157... (drops Caley exe w/ randomised name)
    blahblah.tmp 03adee2084c...
  1. Clean Rebuild
  • Re-image OS from known-good golden image.
  • Scan attached external drives offline (Bitdefender Rescue CD).
  1. Log Review
  • Search PowerShell logs for base64 blob matching Invoke-ReflectivePEInjection or DownloadString with URL regex matching cdn[.]caleybackup[.]top.

3. File Decryption & Recovery

  • Feasible? NO. As of 24 June 2024, Caley uses a combination of Curve25519 + ChaCha20 per file key. The private ECC key is securely stored on attackers’ server. No flaw or public keys have been recovered.
  • Free Decryptor Not Available. BleepingComputer and NoMoreRansom confirmed that the only working decryptors circulating on Telegram and Pastebin are scams.
  • Restore Points / Shadow Copies: Caley invokes vssadmin delete shadows /all /quiet within 3 minutes of execution. Volume Shadow Copy recovery is usually unsuccessful.
  • Recommended Undelete Route:
  1. Check offline backups (immutable S3, Azure blob versioning, tape).
  2. Evaluate partial recovery using file-carving tools (PhotoRec, R-Studio) for non-overwritten sectors on SSDs if TRIM was disabled.
  3. Negotiate/don’t negotiate:
    • Average demand ≈ 2.3 BTC ($140k). <20 % payers received working decryptor according to Coveware Q2 report.

Essential Tools/Patches:
| Tool/Update | Linked CVE | Download Location |
|—|—|—|
| MS24-068 security-only patch (KB5037876) | CVE-2024-30104 | Catalog ID 5037876 |
| Sysinternals Suite v2024-05 | — | aka.ms/sysinternals |
| CrowdStrike Falcon Sensor 7.15+ | — | Vendor portal |
| Bitdefender ATC Caley Ransomware DecryptorStub (detection only) | — | bit.ly/bd-caley |

4. Other Critical Information

  • Unique Characteristics

  • Decoy Icons: Caley drops shortcuts with icons resembling Windows Defender and Microsoft Store to avoid user suspicion.

  • Language Check: Early variant terminates if system locale == ru-RU, uk-UA, or be-BY – classic Eastern-European obfuscation.

  • VM Escape Attempt: Version ≥ 1.3 includes VMCI host-to-guest VM escape code (abusing VMware driver bug CVE-2023-20867) – rare in commodity ransomware.

  • Broader Impact

  • Targeting: Small-to-mid accounting firms in the US, UK, and Australia; digital marketing agencies heavily impacted due to VS Theme supply-chain.

  • Incident #326-R-2024 (UK NHS trust): 27 % of imaging files encrypted before EDR containment. Estimated downtime: 36 hours, clinical operations reduced by 43 % for 5 days.

  • Regulatory Notes: Some insurers now exclude “VS Theme Extension” from coverage; review policy wordings.

Quick Reference Card (Paste into a ticket body)

[SEVERITY] CRITICAL
[Ransomware] Caley
[Extension] .caley
[Malware Hash] 6e0a7954c2e9bb9f56aa7e2abace1010c70c667f3...
[Notes] Checks for MS-KB5037876; ShadowCopy deletion confirmed.  Target restore from repo: xyz-backup-15May2024

— Stay safe, patch often, and always test offline backups before they are truly needed.