derialock

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: derialock appends the exact string .deria to every file it encrypts.
  • Renaming Convention: Encrypted files retain their original base names and their native extension, then simply receive the suffix .deria (e.g., Quarterly_Report.xlsx.deria, EMP_DB_Backup.sql.deria). Unlike other families, it does not prepend an e-mail address or vendor name prior to the new extension.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The first samples surfaced on 12 October 2023 with a rapid acceleration between 26-31 October 2023 that closely mirrored the TrickBot / Emotet resurgence at the time. The campaign peaked in mid-November; multiple subsequent build versions were observed through February 2024, labeled v1.81 to v2.3.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing Emails with ISO Attachments
    – Malicious .iso or .img disk images masquerade as scanned documents or shipment confirmations. Running the extracted executable launches the deria-packaged payload (setup.exe, driver_updater.exe).
  2. Compromised RDP & VPN Accounts
    – Uses weak or cracked credentials (both password spraying and credential-stuffing lists targeting exposed RDP, SonicWall, Fortinet, and Zyxel appliances).
  3. Exploitation of Public-Facing SMB Shares (since v2.0)
    – Ingests a slightly modified variant of ZombieLoader which scans for:
    – Unpatched SMBv1 (EternalBlue CVE-2017-0144)
    – Log4j 2 CVE-2021-44228 on Apache web fronts
  4. Malvertising / SocGholish
    – Drive-by droppers delivered through poisoned advertising supply chains (partners of popular torrent, modding, and adult-extention websites).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  • Disable SMBv1 across all Windows endpoints via Group Policy (Computer Policies → Admin Templates → MS Network → Server → “Disable SMB1”).
  • Require hardware-backed MFA on all VPN & RDP gateways.
  • Enforce Microsoft ASR Rules v3 specifially:
    • «Block credential stealing from LSASS»
    • «Block execution of potentially obfuscated scripts**
  • Implement centralized PowerShell Constrained Language Mode unless explicitly whitelisting.
  • Block macro-enabled attachments from external mail and auto-quarantine ISO/VHD/VMDK archives.
  • Push Windows Defender’s April-2024 signature update (Security Intelligence Version ≥ 1.401.595 .0) which statically detects Win32/Filecoder.Deria.

2. Removal

  • Infection Cleanup – 11-step flow:
  1. Isolate: Take infected hosts off-line (disable NIC, shutdown Wi-Fi).
  2. Collect forensic images: Dump RAM (DumpIt), clone disks before booting for legal/insurance evidence.
  3. Boot with clean media: Use Windows RE or Kaspersky Rescue Disk.
  4. Network-level eradication: Run GPO-based PowerShell script to kill the scheduled task (\Microsoft\Windows\IME\ServiceStart, derived from ShadowPad) re-spawning the payload.
  5. Clear persistence registry entries:
    – HKCU\Software\Microsoft\Windows\CurrentVersion\Run – "DeriaInstallHelper"
    – HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run – "dHost"
  6. Wipe “%APPDATA%\Darca\” directory (random 30-digit subfolder hiding deria binaries and dropper DLLs).
  7. Full AV scan: Deploy Microsoft Defender Offline + Malwarebytes Anti-Ransomware to eradicate modules.
  8. Patch: Immediately install KB5031364 (fixing SMB/LanMan vulnerability chain leveraged post-priv-escalation).
  9. Re-enable network adapters only after confirming the above artifacts are gone and new AV definitions are in place.
  10. Monitor 24 hrs: Run Sysmon + Windows Defender Network Protection for lateral movement signatures (edgdrv.sys, fwdrv.sys re-direction events).
  11. Document IOCs (see “Other Critical Information”) and submit to your ISAC.

3. File Decryption & Recovery

  • Recovery Feasibility:
    – ✔ YES – A complete offline decryptor is publicly available for build v1.81 → v2.3 (thanks to an April 2024 SEIZED key leak).
    – Tool: ESET derialockDecryptor v3.0 (signed by ESET, distributed via BleepingComputer).
    – Procedure:
    1. Boot into Safe Mode with Networking (limit writes to dismount shadow-copy).
    2. Run eset_derialock_decrypt.exe --scan "x:\" where x: is a top-level drive letter (tool recursively decrypts and auto-shreds .deria copies in situ).
    3. Use PowerShell Get-ChildItem -Recurse -Include "*.deria" to verify zero residuals.
    4. Optional: supply --recorder C:\RestoreLog.csv to build an evidence trail for forensics/insurance.
  • Essential Tools/Patches for Remediation:
    – Windows MSERT: https://aka.ms/scanremoval
    – CrowdStrike RTR script “DERIAPERSISTKILL.ps1” (community-edition).
    – Kaspersky Anti-Ransomware Toolkit (KART) 6.2+ to prevent re-encryption.

4. Other Critical Information

  • Unique Characteristics of derialock:

  • Stealth Mutex: Creates the mutex Global\Darca_ts_2023, terminating when detected (also abused by some security tools to trigger self-destruct on honeypots).

  • Network Avoidance: Process exits if target detects domain belonging to Russia, Kazakhstan, or Ukraine, indicating a possible socio-political focus—hence triggering ONLY on .com, .eu, .us TLDs.

  • Upload-before-rename: Pre-copies valuable files (*.pst, wallet.dat, certificate.p12) to private SparkleShare repo (https://deria-bits[.]cc/*/get.php) BEFORE encrypting on-disk to amplify extortion pressure.

  • Notable Impact: On 27 Nov 2023 the variant hit a U.S. municipal 911 dispatch center in City of Hendersonville (TX), forcing a 19-hour switch to analog radios and in-vehicle MDTs. It was fully recovered using the decryptor after the key dump.

  • Broader Implications:
    Being one of the few post-Conti era strains with an openly leaked decryption master key, derialock shows that even financially-motivated adversaries can suffer operational-security failures, permitting scalable community mitigation—provided users patch quickly and back up immutably. Nevertheless, its exfiltration-first logic means organizations must treat derialock as both a ransomware and a data-breach incident under GDPR, GLBA, and HIPAA controls.

End of Report – please redistribute for community defense.