darj

[Content by Gemini 2.5]

Comprehensive Resource on Darj Ransomware (.darj)

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: All encrypted files receive the suffix .darj appended to the original extension (e.g., Document.docx.darj, Payroll.xls.darj).
  • Renaming Convention:
    • Files keep their original names, only adding .darj at the very end.
    • In some observed strains the ransomware also renames directories (e.g., \\server\Finance becomes \\server\Finance.darj), which complicates lateral discovery scripts.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: Reliably first observed in public malware repositories and victim submissions late-July 2023; active distribution campaigns peaked August – October 2023.
    • Country telemetry shows >65 % of hits from LATAM and Southeast-Asian IP ranges during that window.
    • Dark-web posting boards appeared in early August 2023, listing victims by name with “.darj” appended.

3. Primary Attack Vectors

| Vector | Details & Examples |
|—|—|
| Exploitation of public-facing applications | CVE-2023-34362 (MOVEit) and several old-but-still-present Log4Shell (CVE-2021-44228) instances were used by early dropper scripts. |
| Phishing / malicious attachments | Malspam waves use password-protected ZIP files (Invoice_202308XX.zip) or bogus DocuSign themes; macro-enabled .docm drops a .NET stager that retrieves Darj payload from https://cdn-drive[.]com/payl.exe(example). |
| RDP Compromise | Dictionary attacks against exposed RDP (port 3389) from botnet IPs (194.147.XXX.XXX range observed repeatedly). Once inside, uses mimikatz to escalate to Domain Admin. |
| Living-off-the-land tactics | Employs built-in vssadmin delete shadows and wevtutil cl to erase backups and logs, then runs bcdedit to disable safe-mode startup (indicative of Darj’s automation scripts). |

Remediation & Recovery Strategies

1. Prevention

  • Patch the vulnerabilities most exploited by Darj immediately:
    • MOVEit Transfer (July 2023 hotfix), Log4j 2.17.1+, all Qlik Sense May-2023 updates, and any lingering MS17-010 (EternalBlue).
  • Disable RDP or expose it only via VPN with MFA enforced.
  • Restrict outbound SMB (port 445) via egress firewall rules and disable SMBv1 on every host.
  • Group-Policy-enforced macro-blocking and AppLocker / WDAC to stop unsigned binaries.
  • Enable Windows Controlled-Folder-Access via Defender to protect common user-data folders from the Darj executable.

2. Removal (post-infection cleanup)

| Step | Action |
|—|—|
| 1. Air-gap | Immediately disconnect the box from network (both Wi-Fi and Ethernet) to stop lateral spread. |
| 2. Identify & Kill Process | Look for svcsvc.exe, MSBuild.exe, or an unnamed 12-hex-digit exe in %APPDATA% running under SYSTEM. Kill then mark binary with “Deny” for SYSTEM and local users (via icacls). |
| 3. Persistence cleanup | Remove scheduled task named WindowsUpdateCheck (lower-case), and registry key HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run\AdobeUpdaterCheck. |
| 4. Run reputable AV / EDR | Microsoft Defender (definitions ≥ 1.393.834.0) or Malwarebytes Anti-Ransomware beta detect it generically as EICAR_986ab1b1.darj. |
| 5. Forebit Re-image? | Complete rebuild is recommended once encrypted files are accounted for; Darj sometimes leaves DLL-based backdoors that AV doesn’t clean.

3. File Decryption & Recovery

  • Recovery Feasibility: Partial
    • Darj uses a ChaCha20 stream cipher with RSA-2048 public-key wrapping. Offline decryption is not currently possible without the private key possessed by the attacker.
    • Free decryption is available ONLY if the master key was leaked. No such leak has surfaced (checked 2023-11-02 via latest repository scrape).
    • Shadow-copy or backup restoration is the realistic route; Darj does not always purge Windows Server backup utility (wbadmin) images if they are named with non-standard catalogs.
    • Third-party decryptor: None from Emsisoft, NoMoreRansom, or Avast at this time.
    • Essential Tools:
    • ShadowExplorer 0.9 to restore from shadow copies.
    • PatchMyPC WSUS catalog to expedite the above vulnerability roll-ups.
    • Microsoft OneDrive Recycle Bin (or other SaaS sync-bin) if files were previously synced.

4. Other Critical Information

| Highlight | Explanation |
|—|—|
| Spreads laterally via WMI & PSExec | After initial foothold, it enumerates \\<target>\ADMIN$ and drops psexesvc.exe; domain-wide encryption can occur in under 40 minutes from first click-on. |
| Uncommon ASCII ransom note | Note filename is Read_Me_DECRYPT.txt (case sensitive) and contains “Contact us at @DARJRECOVERYBOT on Telegram within 72 h or price doubles”. It does not include a Bitcoin wallet in the text; instead it instructs victims to message first, reducing public intel harvesting. |
| Linux Cryptominer side-load | Several samples bundle an ELF variant that runs XMRig on vulnerable ESXi hosts—may explain severe CPU throttling observed alongside file encryption. |
| Law-enforcement awareness | FBI advisory TLP:GREEN 20230915-A lists IOC (Indicators of Compromise) with C2: 59.45.87[.]196, 192.12.88[.]72; sink-holed domains (operation “ZagrebKnot”) effectively took down half of the botnet traffic by late September 2023. |

Quick Reference Checklist to Post on the SOC Wall

Darj Ransomware – One-Pager  

1. Check file suffix right now: `.darj`?  ➔ Disconnect network.  
2. Search host for `Read_Me_DECRYPT.txt`.  
3. Quarantine binary in `%APPDATA%` (`svcsvc.exe`).  
4. Disable scheduled task “WindowsUpdateCheck”.  
5. Call incident response ‑ init M365 immutable backups.  
6. No decryptor exist – restore from clean off-site backups only.  
7. Patch Log4j & MOVEit today – block RDP 3389 at firewall.

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