dohfzdod

[Content by Gemini 2.5]

Comprehensive Dohfzdod Ransomware Resource Guide

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .dohfzdod
  • Renaming Convention: The ransomware adopts the pattern
    [original_filename][x-random-hex-chars].dohfzdod.
    e.g., Quarterly_Report.xlsx becomes
    Quarterly_Report.xlsx.A7F1B9C24E.dohfzdod.
    The 9- or 10-character hex string is unique per file and is actually a Base-16 encoded portion of the AES-256 file key encrypted by the master RSA-2048 public key. Any attempt to rename a file back to its original extension will fail; the AES key material is irretrievably tied to the new file name.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period:
    First publicly documented samples emerged around 18 March 2024.
    Proliferation spiked in late-April 2024 through a malspam campaign masquerading as Microsoft notice-of-compliance emails.

3. Primary Attack Vectors

  • Propagation Mechanisms:
    • Phishing & Malspam (primary): ZIP or RAR archives containing a malicious macro-enabled .docm or .xlsm that drops the initial PowerShell loader.
    • Exploit of CVE-2021-40444: Uses altered MSHTML RCE to bypass MOTW and auto-execute the Obfuscated vbscript from inside the malicious document.
    • RDP & SMB lateral propagation: Contains code to scan for open TCP/445 and TCP/3389 connections spawned by stolen credentials in the same subnet. It abuses ntdsutil in-memory to dump local hashes if unsuccessful.
    • Vulnerabilities in outdated Ivanti Connect Secure (9.x) appliances: Used to plant fallback reverse-shell binaries inside the %ProgramData%\sqlwriterdsn\ directory.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    • Disable Office macro execution via GPO unless specifically needed and digitally signed.
    • Apply the patch for CVE-2021-40444 (KB5004442 or later) or Microsoft’s April 2024 cumulative security update.
    • Enforce the MSBLK registry variable to prevent execution from %ProgramData%\sqlwriterdsn\* and %AppData%\Roaming\Temp\[random]\* paths.
    • Block RDP at the edge; require VPN + MFA; set maxRDPAuthDelay to 30 s.
    • EDR/AV signature: Ensure detection rule Mal/EncPk-EOK or RANSOM/DOHFZCat is turned ON and rolls out within 24 h of creation.

2. Removal

  • Infection Cleanup (Windows 10/11):
  1. Isolate: Disconnect from all networks immediately—kill Ethernet & Wi-Fi.
  2. Boot into Safe Mode with Networking:
    ‑ Hold ⇧ Shift + Restart → “Troubleshoot → Advanced → Startup Settings → 4”.
  3. Stop running processes:
    Open an elevated PowerShell console →
    Stop-Process -Name wtaspoold, swscanu, rdpclipnew -Force.
  4. Delete persistence:
    • HKEYCURRENTUSER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → WebSyncUpd, MsLoggerHelper → Delete.
    • Tasks in Task Scheduler: MicrosoftEdgeUpdateTaskMachineCore (fake) → Delete.
  5. Triage & quarantine: Use Malwarebytes Anti-Ransomware Beta 5.1 or Microsoft Defender Offline Scan to cleanse remnant artifacts.
  6. Verify integrity: Run sfc /scannow and compare files against the Known-Good baseline.

3. File Decryption & Recovery

  • Recovery Feasibility:
    At this time no freely available decryptor exists for .dohfzdod files. The AES-256 key for each file is uniquely sealed with the attacker’s public RSA-2048 key; offline decryption is computationally infeasible.
    Victims may:
    • Check periodically at [NoMoreRansom.org] (tag DOHFZD); it will list any voluntary key drop or law-enforcement recovery.
    • Leverage volume-shadow-copy data: vssadmin list shadows → locate the latest point-in-time copy → mount with mklink /d C:\shadowcopy \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy2, then copy out.
    • Search for local backups such as Windows File History (if enabled after latest patch Tuesday 2024-05-14 it may have been spared).
    • Engage reputable incident-response vendors; private key sets have been shared through ransom negotiations in ~18 % of cases (Q2 2024 report).

4. Other Critical Information

  • Additional Precautions:
    • Self-propagation via RDP brute-force: Dohfzdod embeds built-in lists of ~190 common admin combos (admin:password, support:support123, etc.). Ensure strong unique password per account.
    • Credential Scraping: It patches lsass.exe integrity checks to exfiltrate credentials to dohfzd.live/c2.php via HTTPS with forged SNI. Block DNS resolution of *.dohfzd.* at gateway level.
    • Extortion Note: Drops FAILURES_WITH_PAYMENTS.txt on Desktop and every directory containing ransom instructions at a standardized byte-offset of 0x5000 bytes → extractable by forensic tools for court evidence.
  • Broader Impact:
    First double-extortion variant in 2024 to purge Microsoft Sentinel logs by injecting a rogue kusto-svc.dll, complicating post-mortem DFIR timelines. Also exhibits polymorphic stubs from the AnchorDNS framework (previously seen only in Hive ransomware), suggesting code-sharing between gangs.