dablio

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .dablio (note the lowercase spelling).
  • Renaming Convention: Each encrypted file is appended “.dablio” as a secondary extension while leaving the original extension intact.
    Example: Quarterly_Report.xlsx → Quarterly_Report.xlsx.dablio
    No base-name or UUID prefixing is used—only the new extension is added.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Active campaigns first surfaced in late-November 2022 (earliest uploads to public malware repositories on 2022-11-27). Rapid flare-ups occurred through December 2022–January 2023 and sporadic waves have continued into 2024.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Spam-phishing – ZIP or ISO attachments containing malicious .wsf, .js, or .lnk droppers that fetch the Dablio loader from Discord CDN or GitHub repositories.
  2. Brute-force RDP – Self-propagates laterally once an initial foothold is achieved.
  3. Downloader Trojans – Existing infections (e.g., LokiBot, Vidar) deliver Dablio as a 2nd-stage payload.
  4. Unpatched firewalls/VPN appliances – Exploits* known to be chained against weakly configured SonicWall, Fortinet, and MikroTik services for external entry.
    No specific CVE proven to be unique to Dablio; it reuses off-the-shelf exploits.

Remediation & Recovery Strategies:

1. Prevention

| Priority | Action |
| — | — |
| Harden RDP | Disable RDP or limit access via VPN + MFA; enforce strong complex passwords and lockout policies. |
| Patch Everything | Apply January 2023 cumulative Windows Update (and later) to fix publicly weaponized Win32k/Print Spooler escapes Dablio uses for SYSTEM escalation. |
| E-mail Filtering | Block inbound .wsf, .js, .vbs, .hta, .iso, and .zip from unknown senders; enable sandbox detonation. |
| Attachment Restrictions | Use Group Policy to prevent execution of scripts from %TEMP%, %APPDATA%, and mail-download locations. |
| Application Allow-listing | Enable Windows Defender Application Control (WDAC) or a 3rd-party endpoint allow-listing solution. |
| Log Monitoring | Hunt for PSExec/WinRM usage outside of change windows; monitor for rapid enumeration of .vhdx/.sql/.pst files. |

2. Removal (Step-by-Step)

  1. Isolate – Immediately disconnect the affected host from the network (pull cable / disable NIC).
  2. Boot to Safe-Mode with Networking – Prevents Dablio’s anti-kill mutex from re-launching.
  3. Identify Persistence – Look for the main binary dropped under:
  • %APPDATA%\Roaming\DrvHost32.exe
  • %PROGRAMDATA%\MicrosoftHelp\DrvHost32.exe
    plus registry run keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
  1. Terminate malicious processes using Task Manager or RKill (manual name matching: DrvHost32.exe, MANAGER-DESK64.exe).
  2. Scan & Clean – Run Malwarebytes 4.5+, ESET Online Scanner, and a full Windows Defender Offline sweep.
  3. Delete Shadow Copies Restore – Re-create if none, or verify existing ones are intact.
  4. Patch and Reboot – Apply OS and firmware patches, then reboot into normal mode and re-scan to confirm eradication.

3. File Decryption & Recovery

| Aspect | Answer |
| — | — |
| Decryption Possible? | Yes, partially. Dablio is built on Chaos ransomware 4.x source code and uses a hard-coded 32-byte key (AES-256 in CBC mode). Researchers at Emsisoft reversed the sample, recovered the key, and released a free decryptor. |
| Recovery Procedure | 1. Download Emsisoft Decryptor tool “DablioDecrypter.exe” (Oct-2023 build or later).
2. Run it on an offline copy of encrypted data to avoid interference with the running OS.
3. Provide original un-encrypted pairs if known (e.g., a backup Word doc with the same file size); otherwise brute-forcing is unnecessary because the key is known.
4. Tool outputs a log confirming number of successfully decrypted files. |
| Ongoing Applicability | As of 2024-05-18 all publicly collected samples include the same hard-coded key—decryptor remains effective. Check for updated decryptor version should a new wave appear. |

4. Other Critical Information

  • Unique Characteristics

  • Russian/Brazilian hybrid chatter: ransom notes (README.txt) in both Portuguese and English with Cyrillic metadata strings—a hint of shared builder kits.

  • Chaos-like wiper fallback: Deletes backups via WMIC shadowcopy delete; if run on drives larger than 2 GB it falls into “fake encryption” mode (random 512 KB chunks overwritten despite .dablio extension).

  • Discord C2: Uses Discord webhook URLs for victim exfiltration and status pings, so blocking discord.com/api/webhooks/* at proxy level can hinder data leakage.

  • Broader Impact

  • Brazilian municipalities and health-care NGOs hit hardest around Christmas 2022 (public record via CERT.br).

  • High overlap with “Chaos 5.0” campaigns (Jan-May 2023) indicates a wider malware-as-a-service ecosystem; identical decryptor applies to overlapping Families.

  • Demonstrates reuse of low-effort Chaos forks proves actors buy cheap builders—swift return to profitability with minimal dev cost.

  1. Free Decryptor: Emsisoft – Dablio Decryptor
  2. Offline Scanner ISO: Windows Defender Offline
  3. Patch Roll-ups: January 2023 Windows Security Update.
  4. E-mail Gateway Preset: Microsoft Defender for Office365 – SafeAttachments+SafeLinks configuration templates.

Stay patched, stay backed-up, and test offline backups regularly.