crown

[Content by Gemini 2.5]

Comprehensive Resource on the “Crown” Ransomware Family

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: The Crown locker appends the .crown extension verbatim (lower-case, no preceding dot if the original file already contained an extension).
  • Renaming Convention:
    Original file: Report_Q3_2024.xlsx → Encrypted file: Report_Q3_2024.xlsx.crown
    Very long filenames may be truncated to the first 100 characters to avoid Windows PATH limits. Folder-level “decryption instructions” (HELPDECRYPTYOUR_FILES.txt) are dropped in every directory that contains at least one encrypted object, but folders themselves are not renamed.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: The first telemetry hits and public ransom notes surfaced around late-Q3 2023 (mid-September 2023). A second, larger wave—using updated packers and broader distribution channels—peaked between March–May 2024. Signatures now exist under threat names such as Ransom:Win32/Crown.A, Ransom.CROWN, and CrowdStrike’s “CROWNCRYPT”.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. Phishing Emails with ISO Attachments – Payload hides inside a ~700 KB optical-disc image masquerading as an invoice or shipping label; the ISO contains a hidden .LNK pointing to install.exe.
  2. Compromised RDP / VNC Credentials – Crown operators systematically brute-force Internet-facing terminals (port 3389, 5900). Post-breach they deploy Cobalt-Strike BEACON, then push Crown via PSExec.
  3. EternalBlue (CVE-2017-0144) re-publication in Q4-2023 campaign variants – Specifically against legacy Windows 7/Server 2008 networks that never received MS17-010.
  4. Software Exploits – Notable abuses include:
    • CVE-2023-34362 (MOVEit Transfer)
    • CVE-2023-2868 (Barracuda ESG appliance)
  5. Malvertising via fake software updates – Fake Google Chrome or PuTTY installers served by typosquat domains (“chrоme-update.dev”, note the Cyrillic “о”) drop the initial loader.

Remediation & Recovery Strategies:

1. Prevention

  • Perimeter Controls: Block Internet RDP ports (TCP 3389/5900) or force VPN + MFA; use IP allow-lists.
  • Patch Frenzy: Apply the May-2024 cumulative Windows Update (which contains the newest Defender AMSI detection logic for Crown packers). Patch MOVEit, Barracuda ESG, and ensure MS17-010/EternalBlue mitigations.
  • Email Hardening:
    • Strip ISO and LNK attachments at the gateway (or at least quarantine them).
    • Enable Office “Block macros from the Internet” (GPO).
  • Endpoint Hardening:
    • Deploy EDR with behavioral monitoring—Crown creates mutex Global\92aebed1-crown and touches the registry key HKCU\SOFTWARE\crown. Flag both.
    • Enable Windows Credential Guard and disable WDigest (reg add HKLM\…\UseLogonCredential /t REG_DWORD /d 0).

2. Removal – Step-by-Step Infection Cleanup

  1. Isolate hosts: Unplug NIC, disable Wi-Fi, and suspend connected hypervisors via orchestration scripts.
  2. Identify persistence:
    • Scheduled task named “Crown Updater” (C:\ProgramData\CrownSrv.exe).
    • Service “CrownsHost” pointing to %AppData%\cro\dmn.exe.
  3. Boot into Safe Mode w/ Networking or WinPE; mount registry hives offline if needed.
  4. Delete files & registry artifacts:
    • %ProgramData%\CrownSrv.exe, %AppData%\cro\*
    • Run keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run (CrownAssistant).
  5. Scan with up-to-date Defender / reputable AV to remove BEACON and PowerShell backdoors that typically coexist.
  6. Reboot to full Windows and redo AV scan to ensure no residual second-stage payloads.
  7. If domain compromise is suspected: Immediately force password resets and re-image affected workstations. Rotate Domain Admin KRBTGT keys offline.

3. File Decryption & Recovery

  • Recovery Feasibility for .crown Files:
    • A public decryptor was released by Emsisoft in June 2024 after the Crown master RSA key was leaked on a Russian-speaking forum.
    • Figures as of 2024-07-01: ≈93 % of known Crown samples are decryptable; the remaining 7 % use a later revision that regenerates RSA keys per campaign. Search your ransom note SHA-256 on Decryption-Verification API to verify compatibility.
  • Essential Tools & Documentation:
    • Emsisoft Crown Decryptor v1.2.0.1 (portable, offline mode recommended).
    • KapeTools CrownKiller – Automates removal of all mutexes and scheduled tasks.
    • “Crown-Check” PowerShell script – Scans for any leftover backdoors (Find-CrownArtifacts.ps1).
  • Patches to prevent reinfection: MOVEit patch (April 2024 hotfix), Barracuda firmware 10.1.2.004+, Windows KB5034441.

4. Other Critical Information

  • Unique Artifacts: Each Crown ransom note contains an ASCII “royal crown” and the line “We will treat your data like our royal treasury – unless you pay.” The note insists on using the Tails OS and Protonmail-after-72-hours fallback—not seen in most families today.
  • Data Leak Platform: Crown operates a TOR-based leaks site called “CrownDump”. Victims are given 7 days before records are posted; screenshots released so far show stolen SharePoint vaults but no mailboxes.
  • Insurance Caveat: Several U.S. and EU cyber-insurers updated their post-July exclusion clauses regarding Crown infections; verify policy language before deciding on ransom payment (which is strongly discouraged regardless).

Stay vigilant, patch early, and share IoCs with peer organizations—collective visibility is our best long-term defense against the Crown ransomware dynasty.