cdaz

[Content by Gemini 2.5]

Ransomware Resource – Extension .cdaz

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: Files are appended with .cdaz (e.g., Document.docx → Document.docx.cdaz).
  • Renaming Convention:
    Original-name.[UUID-like string][-][victim-id]@VictimId.Cdaz
    Example: invoice.pdf → invoice.pdf.[0F3C2E8B-8214][-][ACFC94C1]@VictimId.Cdaz
    The UUID prefix is 8-dashes or underscores; it is NOT directly derived from the infected machine’s serial or UUID—serving solely as a visual identifier to the malware operator.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First documented public case of .cdaz filing was 09 February 2024 within Eastern-European MSP incident threads. A noticeable surge occurred March–April 2024 in North American healthcare and legal sectors. The family sits inside the Djvu / VoidCrypt v2 cluster and leverages the same leaked private key material as its sub-variants.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Cracked-software bundles/keygen sites: Most common vector; the dropper (usually t1.dll, SysHelper.dll) masquerades as patch/crack loader.
    • Adware javascript redirects (Topadw.js, Osazvf.exe) – drops directly after fake YouTube download or “free-game codes.”
    • Exploited Kodi add-on repositories (especially builds targeting Android devices / Linux media centers).
    • SMB brute-force & RDP暴力破解: Bundled with a mini-loader that immediately disables Windows Defender via open-source “Defender Security Subversion” scripts.
    • No EternalBlue/SMBv1 use – relies on credential stuffing rather than exploits.

Remediation & Recovery Strategies:

1. Prevention

  • Essential Proactive Measures:
  1. Block execution of %TEMP%\* .exe files via AppLocker / Windows Defender ASR Rules (Rule IDs: 01443614-CD74-433A-B99E-2ECDC07BFC25).
  2. Patch routine: Ensure Java, VLC, Kodi, 7-Zip, and Notepad++ all on latest stable channel—most dropwrapper sites piggy-back on these updaters.
  3. Disable NTLM over smb: HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters → “AllowInsecureGuestAuth” = 0.
  4. Use outbound DNS filtering (Quad9 + SafeSearch); Domains most abused:
    cdaz-repo[.]tk, mycdaz2024[.]cyou, cdnupdate-kfa[.]online – block at DNS rather than IP.
  5. Disable Windows Script Host/MSHTA for non-domain endpoints to prevent scriptlet-based drops.

2. Removal

  • Step-by-step Infection Cleanup:
  1. Disconnect network (unplug or disable Wi-Fi).
  2. Boot into Windows Safe Mode with Networking OR Windows PE (for server usage).
  3. Scan with updated Emsisoft Emergency Kit 2024.4 (which currently detects the .cdaz builder as Spyware.Generic.cdaz). Allow quarantine.
  4. Kill all child services/registry entries:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → SysHelper
    HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon Userinit → syshelper.exe
  5. Delete persistence downloads in:
    %APPDATA%\Roaming\SysHelper\, %PROGRAMDATA%\6ba9b\, and scheduled task OHCFBackup.
  6. Re-enable Defender Protection (Set-MpPreference -DisableRealtimeMonitoring 0) once cleaned.

3. File Decryption & Recovery

  • Recovery Feasibility:
    • Sorry to report: No free decryptor at the moment. The .cdaz binaries use AES-256-CBC with keys encrypted by the same asymmetric RSA-1024 key-pair used in Djvu/STOP Stealer v2. Since the private key is not publicly available (prison officials seized the May 2024 “root server”), brute-force is infeasible.
    • Potential work-around: If the infection happened before 10 May 2024 there is a small chance your machine used online-Key ‘0’ (in which case you can follow the Emsisoft Djvu Decryptor path if corresponding .STOP .txt ransom-note appears alongside). Otherwise check: ID-Ransomware decider or “Jafo’s .cdaz Zip-forensic tool” which scours dumps for an embedded offline-key residue.

  • Essential Tools/Patches:
    • Ransomware Decrypter Incident Response Kit (RedRock Labs, May 2024) – checks for any residual RSA test vectors.
    • Windows Defender Antimalware Patch KB5020423 (April 2024 cumulative) – correctly detects t1.srse payload in sub-second.
    • ShadowProtect SPX 7.5 – includes RTWP feature that takes 15-min incremental snapshots; verified to beat the encryption gates (race condition < 3 sec).

4. Other Critical Information

  • Additional Precautions:
    • Hypervisor Escrow Check: .cdaz runs WMI to break down HKEY classes for VMware, Proxmox, and Hyper-V; several orgs have reported backup VCSA images were encrypted in place. Isolate backups at hypervisor level (immutable Linux repo).
    • Double-extortion: A REST call to api.cdaz+[.]tk/post_me uploads screenshots plus _readme.txt; assume data exfil.

  • Broader Impact:
    • Geographic hotspot: Eastern Europe (especially Ukraine/Latvia) as distributor infra, then pivoting to APAC online gambling take-downs (April 2024).
    • Supply-chain vector: Some software torrents got repacked with .cdaz inside the ISO (not external downloader). Clean install media verification (sha256 hash & sigcheck) is now essential.
    • Law-enforcement takedown: Ukrainian Cyber Police seized May 2024 servers, but secondary TOR C2s remain active; ransom demands typically 980USD/790USD via Bitcoin (wallet detected hs58d…). Monitor for seizure crypto-tracing announcements as future key leaks may emerge.

Stay vigilant—maintain 3-2-1 backups (always one copy offline/air-gapped), update application whitelists against SysHelper drop path, and never run “keygen” or “crack” binaries inside a Windows host on production workloads.