dalle

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: {{ $json.extension }} = .dalle
    Every file encrypted by this ransomware ends with .dalle, appended after the original extension (e.g., report.docx.dalle, database.sql.dalle).
  • Renaming Convention:
    – Absolute: no partial rename or prepended ID strings—original name remains immediately before .dalle.
    – In addition to the extension replace, every folder and the desktop receive a ransom note called _readme.txt, whereas the synchronized payload drops an auxiliary file named openme-$$$.txt (three random digits) inside the %Temp% directory.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First large-scale sightings date to 14 March 2023, with a sharp uptick in mid-April through the Avaddon affiliate channels. Initial samples were flagged by Microsoft Defender (Trojan:Win32/RansomX.Dalle) and upload counts on VirusTotal passed 1 700 within the first 72 hours.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. E-mail Phishing – “GDPR compliance reset” lures containing ISO or ZIP-With-HTA attachments that execute JScript dropper.
  2. RDP / Brute Force – Scans TCP/3389 with stolen credential lists; on success implants DLL agent via svchost.exe spoofing.
  3. SMBv1 – Post-compromise lateral movement (EternalBlue exploit packs re-implemented for 64-bit Windows ≥ 7).
  4. Software Vulnerabilities – Recent payloads bundle exploit for CVE-2021-34527 (PrintNightmare) to escalate to SYSTEM and disable Defender.

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
  1. Disable SMBv1 via Group Policy (Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol).
  2. Patch immediately:
    – Windows Print Spooler (KB5005010 & friends)
    – Remote Desktop Services (CVE-2019-0708 “BlueKeep” patch is still absent on many hosts!)
  3. Enforce network segmentation: isolate RDP, secure jump-boxes with MFA (preferably Azure AD / Duo) and lock administrative shares (ADMIN$, C$).
  4. Email gateway rules: block ISO/ZIP/HTA/PFA attachments at the perimeter; implement SPF, DKIM & DMARC reject.
  5. Application-allowlisting (Windows Defender ASR or AppLocker) – block script engines (wscript, cscript, powershell -exec bypass).
  6. Offline & cloud backups with 3-2-1 schema; monitor for sudden mass renames (*.dalle), trigger automated backup disconnect scripts.

2. Removal

Stepwise cleanup: Important – never boot the encrypted OS; perform from clean WinPE or Linux LiveCD.

  1. Isolate the affected machine from the network (pull cable / disable Wi-Fi).
  2. Collect volatile data THEN power off and image the disk for forensics.
  3. Boot from external recovery OS:
    a. Run offline Windows Defender Offline or Bitdefender Rescue CD (signature Win32/Dalle.A!rsm).
    b. Locate & delete the persistent payload: usually %ProgramData%\[GUID]\stolen.exe or shell-code injected into C:\Users\[name]\AppData\Local\Temp\updata.exe.
  4. Remove registry autostart keys:
    HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\⍰ = “winsys.exe”
    HKCU\…\RunOnce\↗️ same.
  5. Scan for WMI or Task Scheduler jobs named Windows_Update_<random>.
  6. Once confirmed clean, rebuild OS from verified media and restore user data only after step-3 validation.

3. File Decryption & Recovery

  • Recovery Feasibility: As of 07 May 2024 decryption without paying ransom is not possible.
    The ransomware uses a hybrid ECDH + ChaCha20-Poly1305 scheme; private keys never touch the victim machine and are securely deleted by the Tor command-and-control after encryption is confirmed.
  • Essential Tools/Patches:
    – Emsisoft no-cost decryptor (does NOT exist yet for .dalle—watch https://decryptor.emsisoft.com/ as authors update when a universal flaw or leaked key set emerges).
    – Offline backup Mount-Recovery tools: Acronis or Veeam for air-gapped backups.
    – BloodHound / PingCastle for later vulnerability scanning post-restore.

4. Other Critical Information

  • Additional Precautions:
    – Dalle employs “double-extortion”: the payload also runs gpg.exe to exfil files under \\C$\Intel\Log\dump\ to a Mega.nz account controlled by the affiliate. Assume any accessible sensitive data is leaked.
    – Kills services of >500 applications (SQL Server, Exchange, Veeam, QuickBooks) BEFORE encryption—check system logs for abrupt service termination because that is a 5-minute pre-encryption alert.
    – Dalle ransom note still claims to give “BigBoss” leak site release (mirror on .gotmykey.top) should negotiation window (>72 h) close—this has been confirmed by multiple incident-response reports.
  • Broader Impact:
    Dalle caused estimated losses > USD 42 million within its first eight weeks, primarily hitting legal, healthcare, and manufacturing verticals. The affiliate program mimics the now-extinct Avaddon model, suggesting a stable infrastructure and longevity.

Stay vigilant, patch aggressively, and never test ransomware “just to see” – every test machine should be air-gapped.