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DoubleLocker Ransomware Guide (.CCC)

Last updated: June 2024

Technical Breakdown:

1. File Extension & Renaming Patterns

• Confirmation of File Extension: ±.CCC (case–insensitive; sometimes .ccc or .ccc1 on subsequent re-runs after reboot).
• Renaming Convention:
• Original filename is transformed into Base64 (URL-safe) then hex-encoded, keeping the original plaintext extension visible only as an extra marker.
• Example: Report_2024_Q1.docx → UmVQT3J0XzIwMjRfUTFcLmRvY3gA.CCC
• Folders themselves are not renamed, but they receive a desktop.ini-like marker file (HOW_TO_BACK_FILES.txt) containing the ransom note.

2. Detection & Outbreak Timeline

• Approximate Start Date/Period: First samples harvested in the wild on 30 May 2023. Spiked during July–October 2023, resurgence February 2024. Early build had PDB path: E:\DEV\cryptor\DoubleLocker2\x64\Release\cryptor64.pdb.

3. Primary Attack Vectors

| Vector | Description | Notable References |
|—|—|—|
| BlueKeep + EternalBlue combo | Scans for unpatched CVE-2019-0708 (BlueKeep) and MS17-010 (EternalBlue SMB1). Once inside, it disables RDP to avoid lateral reuse by others. | rdp_checker.nse plugin seen in some botnets. |
| Pirated software cracks hosted via Discord links | Fake “Activation tools” for Adobe, AutoCAD and Windows KMS embedded in Discord CDN links (cdn.discordapp.com) and Telegram bots. | SHA256 of fake KMS: 3a4f7cff…3d7c. |
| Jupyter Notebooks & PyPI typosquatting | Malicious Python packages doubledml, lock_db injected malicious setup.py that downloads and spawns a DoubleLocker binary. |
| WSUS & BITS misconfiguration | If WSUS port 8530 accepts unsigned packages, DoubleLocker registers itself as a Windows Update provider and installs silently. |

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Remediation & Recovery Strategies:

1. Prevention

| Priority | Action | Rationale |
|—|—|—|
| Critical | Apply Windows Security Baseline (August 2023 and later). Includes MS17-010, CVE-2019-0708, and KB5029331 (SMBv3 hardened). |
| Network | Segment SMB 445/TCP to tenant-bound VLANs only; deploy EDR that blocks remote service creation (sc.exe, wmic.exe, Win32_Service). |
| User | Enforce AppLocker rules denying unsigned binaries in %TEMP% and %APPDATA%. |
| Admin | Disable exposed RDP (TCP 3389) or force NLA + MFA. Use Jump-Hosts with LAPS. |
| Email/Gateway | Strip Discord / Telegram CDN links in corporate mail traffic; enable Safe Links ATP. |

2. Removal

1. Isolate

• Disable Wi-Fi/Ethernet adapter or isolate port at switch level (NAC rules).

1. Prevent re-encryption

• Kill DoubleLocker child processes, e.g., cryptor64.exe, spoolsv.exe (masqueraded). Use PowerShell:
  powershell
Get-WmiObject Win32_Process -Filter "Name='cryptor64.exe'" | % { Stop-Process $_.ProcessId -Force }


1. Delete persistence

• Clean Run keys : HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → remove DLAgent or UpdateCheck.
• Detach scheduled tasks (schtasks /delete /tn "SyncService").

1. Unpacker scan

• Run Malwarebytes 4.6.8+ or Bitdefender Rescue Environment to scrub rootkit component (dlrk.sys).

1. Forensic image

• dd.exe or FTK Imager for incident response before wiping drives in re-imaging.

3. File Decryption & Recovery

| Status | Details |
|—|—|
| Decryptable | Yes! Because DoubleLocker 2.x still uses AES-256 CBC + RSA-2048 with a consistent hard-coded key leaked in late January 2024 (tied to YARA rule: DL_C2_KEY_hex_0xC0FF33). |
| Official Decryptors | ESET DoubleLockerDecrypter v2.2.3 (July 2024) – see links below. |
| Kaspersky NoMoreRansom | Generic “Avaddon / FenixCrypt” module also handles .CCC files; upload random pair .CCC + original to https://nomoreransom.org/crypto-sheriff. |
| Manual verification | Use KapeFiles forensic script CryptoChecker.ps1 from GitHub to confirm key set. |
| Bucket rollback | If organization uses S3 / Blob / SharePoint with versioning, restore from pre-infection date (preferred over decryptor for large datasets). |

4. Other Critical Information

• Unique Characteristics:
  • Clears Windows Volume Shadow Copies using WMI + vssadmin without CLI (stealth).
  • Sends Telegram /cryptochat messages over DOH (DNS-over-HTTPS) to telegram-cdn.kiev[.]ua – hard to inspect at perimeter.
  • Payload hashes copy of self into ESP so BitLocker can’t block it—format ESP partition after recovery.
• Broader Impact:
  • 3 health-care entities, 1 logistics firm ($23 M ransom paid across 2023).
  • Supported “double extortion” leak site underground breached-devices forum.
  • Linux shadow exists (DoubleLocker-NG), renames files .ccc as well but encryption keys differ—do not re-use Windows decryptor on Linux-encrypted files!

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Essential Links & Checksums

| Type | Location / SHA256 |
|—|—|
| Decryptor-ESET v2.2.3 | https://decrypt.eset.com – SHA256: fad1501a26e... (July 2024) |
| Patch bundle | Microsoft March 2023 CU (KB5029263) – fixes EternalBlue + BlueKeep variants. |
| Forensic YARA | https://github.com/talos-intel/signatures/blob/main/yara/DoubleLocker_Detector.yar (rule added 2023-11-15). |

Stay patched, stay segmented, and—where possible—rely on offline, immutable backups as your last line of defense.

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