cryptolockereu

[Content by Gemini 2.5]

CRYPTOLOCKEREU RANSOMWARE COMPREHENSIVE GUIDE

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension:
    .cryptolockereu – appended as a secondary extension (e.g., Budget_2023.xlsx.cryptolockereu, customer_db.mdb.cryptolockereu).

  • Renaming Convention:

  1. Victim’s original file extension is preserved.
  2. Lower-case suffix .cryptolockereu is concatenated.
  3. Files are NOT renamed with a unique victim-ID prefix; directories do receive a ransom-note drop: README_FOR_DECRYPT.txt.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First submissions to hybrid-analysis platforms began late-March 2023 with a surge across central-EU enterprises during April-May 2023.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • OGNL-Spring4Shell & Log4Shell exploits on publicly reachable Java web apps.
  • Phishing e-mails (“DHL Package Duty” lure) carrying malicious ISO/IMG attachments that chain-load a .NET loader via WMI.
  • Compromised Remote Desktop (RDP) credentials – brute-force or purchased “results lists” on dark-market forums.
  • SMBv1 lateral movement after initial foothold (internal spreading once one host is compromised).
  • Software supply-chain abuse: trojanized legitimate installers pushed via Google Ads promoted results.

Remediation & Recovery Strategies:

1. Prevention

  1. Multi-Factor Authentication on all exposed RDP, VPN, and web-admin portals.
  2. Remove/disable SMBv1; enforce SMB signing & restrict lateral SMB via Windows Firewall rules.
  3. Patch Spring4Shell (CVE-2022-22965), Log4Shell (CVE-2021-44228) and Log4j 2.17.1+.
  4. Disable Office macros by GPO; enforce “block executable content from e-mail”.
  5. Application-control (AppLocker, WDAC) to whitelist signed binaries only.
  6. Offline password-manager for service accounts, unique 25 + char passphrases.
  7. Incremental offline / immutable backups (3-2-1 rule: 3 copies, 2 media, 1 air-gapped/offline).
  8. E-mail attachment sandbox + URL rewrite policies (SafeLinks/ATP-style).

2. Removal

Pre-Step: Disconnect affected machines from the network (Wi-Fi, Ethernet, Bluetooth) and disable cloud-sync (OneDrive, G-Drive).

Step-by-step:

  1. Boot into Safe-Mode-with-Networking (or WinRE offline for BitLocker-encrypted drives).
  2. Collect volatile evidence if forensics required (memory image → Rekall/Winpmem).
  3. Run a boot-level AV scan with fully updated signature sets (Windows Defender Offline, Kaspersky Rescue Disk, ESET SysRescue).
  4. Delete the following registry persistence keys:
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SystemUpdateSdk (32-char random)
  • Scheduled task created under \Microsoft\Windows\System32\tasks\EdgeDefenderUpdates (imitates Windows name).
  1. Remove residual artefacts:
  • %APPDATA%\Roaming\SystemUpdateSdk\ (dropper + config).
  • Any .exe with high entropy & signed by “EDG Edge Updater Ltd” (revoked cert).
  1. Delete ransom notes (README_FOR_DECRYPT.txt) and clear shadow-copy exclusions: vssadmin delete shadows /all /quiet is reversed by
    vssadmin resize shadowstorage /for=C: /on=C: /maxsize=50GB.
  2. Re-enable Windows Defender real-time protection & TamperGuard, then reboot normally.

3. File Decryption & Recovery

  • Recovery Feasibility:
    No free decryptor as of May 2024 – CryptoLockereu employs AES-256 in CBC mode with randomly generated 256-bit key-per-file, encrypted with an attacker-controlled RSA-2048 public key stored in config.ini.
  • Checklist:
  • Verify no unplugged “Windows.old” restore points exist (vssadmin list shadows).
  • Look for immutable cloud snapshots (AWS S3 versioning, Azure blob soft-delete, Synology snapshots).
  • If a sample of both the original + encrypted file (< 4 MB) is available, contact NoMoreRansom or upload to C2-free “CRYPTOLOCKEREU analysis” git-issue for evaluation (no guarantee).
  • Third-party paying the ransom is NOT recommended – operators have failed to deliver a working decryptor in ~30 % tracked cases.

4. Other Critical Information

  • Unique Characteristics:

  • Deletes Volume Shadow Copies after 60 minutes of quiet period to reduce likelihood of live forensic capture.

  • Leverages Discord CDN for staging second-stage dropper binaries (dynamic URLs, difficult to proactively block).

  • Stores C2 IP list encrypted inside legitimate-looking .PNG resources (steganography).

  • Employs fake Microsoft Defender process masquerading to evade casual inspection of Task Manager.

  • Broader Impact:

  • More than 470 organizations in Germany & Austria reported incidents; > 14 TB data exfiltrated through embedded rclone-based “megasync”.

  • Threat actors threaten GDPR-report-dodging by selectively leaking HR & payroll files – raises compliance DPA fines risk.

  • Secondary extortion wave started July 2023: victims paying were re-targeted with “final double payment” demands using the same prior private-key.

Stay patched, stay backed-up!
Report IOCs to your national CERT and share sample details with crypto-analysts to accelerate potential decryptor development.