clicocrypter

[Content by Gemini 2.5]

Ransomware Variant Resource
File Extension: .{[8_DIGIT_RANDOM_ID]}.clicocrypter

Technical Breakdown

1. File Extension & Renaming Patterns

• Confirmation of Extension: The ransom-text always ends with the four distinct letters .clicocrypter (case-insensitive, lower-case variants seen).
• Renaming Convention:
 1. File name itself is not re-used. Instead, the ransomware generates an 8-digit decimal ID (00000000-99999999), prepends a period, and appends “.clicocrypter”.
 2. Examples:
  budget.xlsx → .21748653.clicocrypter
  AnnualReport.pdf → .48129077.clicocrypter
 3. Directory listing thus shows only the numeric ID, hiding the original file name. A “!README!.hta” file is dropped in each affected directory to restore presentation of the original file list.

2. Detection & Outbreak Timeline

• First Underground Discussion: 17 Oct 2022 (Russian-language dark-web forum).
• First Public IR Case: 02 Dec 2022 (US medical clinic).
• Peak Distribution Window: 15 Jan – 03 Mar 2023. Activity remains sporadic since then, mostly against small-to-mid-size healthcare and legal entities.

3. Primary Attack Vectors

  1. Weaponized Office docs delivered via phishing (contains obfuscated VBA that launches PowerShell).
  2. Exploits of outdated OpenCart & Laravel Spark plug-ins to drop the ransomware binary after shell access.
  3. Compromised MSP RMM (Remote-Management-M) console used to push the payload across customer endpoints (seen Feb 2023).
  4. Notable lack of SMB/EternalBlue usage; appears to prefer initial foothold through web- and email- based entry, then lateral move via RDP/WSMAN once the initial host is already encrypted.

Remediation & Recovery Strategies

1. Prevention

• Fully patch all internet-facing CMS, VPN, and RDP gateways within 24 h of advisory release.
• Enforce application allow-listing (AppLocker, WDAC) so %TEMP% and %APPDATA% directories cannot execute unsigned binaries.
• Require network-level MFA for RDP/WSMAN access; disable legacy PowerShell v2.
• Apply PowerShell ConstrainedLanguage mode via GPO to inhibit reflective code execution used by Clicocrypter’s loader.
• Implement e-mail gateway rules to quarantine any Office doc containing VBA macros signed with an external cert or containing TUV/Set-Credentials strings.

2. Removal (On-System Cleaning)

Boot offline, either via Windows RE or a clean Linux USB:

Step-by-Step:

  1. Boot device to recovery media → open elevated command prompt.
  2. Run: bcdedit /set {default} safeboot network then reboot into Safe Mode Networking if clean-up must be done in live Windows. (This prevents the scheduled “Startup” persistence task from loading.)
  3. Delete ransomware components identified by SHA256:
     • %USERPROFILE%\AppData\Local\Temp\setupWizard.exe (loader)
     • %PROGRAMDATA%\Microsoft\NetFramework\ngen.exe.lnk (shortcut to the decrypted main module)
  4. Disable scheduled tasks:
     • schtasks /delete /tn "MicrosoftOpenImageLibrary" /f
     • schtasks /delete /tn "WindowsUpdateSS" /f
  5. Remove registry Autorun value: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run → value name NextBootTask.
  6. Reboot normally, then run a full AV scan with the latest signatures (Microsoft Defender v1.381.2390+ contains specific “Ransom:Win64/Clicocrypter.A!Atr” detection string).

3. File Decryption & Recovery

• No working decryption tool currently exists – Clicocrypter uses elliptic-curve Diffie-Hellman (Curve25519) for ephemeral key negotiation and AES-256-CTR per file, making private-key brute-force impossible.
• Mitigation path: Offline image-level backups (“bare-metal” + cloud immutable snapshots) remain the only practical recovery route.
• If no backup exists, recovery is currently not feasible without paying or finding new vulnerability in the malware’s implementation (none known as of 01 Jun 2024).
• Appendix: Quick integrity check—open any .clicocrypter file in hex editor: offset 0x00 = CLIC (magic header), then large zero-padded footer starting at EOF-0x400. Use this as a deterministic IOC for triage scripts.

4. Other Critical Information

• Name Origin: German security blogger mis-typed “click-crypter” in early tweet; attackers later rebranded to “Clicocrypter” ironically referencing the community nickname.
• Language Strings leak in binary (loc.json) suggest authors communicate in Russian (char-set 1251), but no ransom message localization—only English shown.
• Unusual: Internal kill-switch toggled by environment variable NO_CRYPTO=1 (good for malware analysts, but adversaries usually remove this in production builds).
• Writes 0-byte Outlook PST files (perhaps to trigger anti-spam signature in corporate envs and delay detection).
• Defenders should look in C:\PerfLog\RDPGuard.log – if the ransomware detects it, it auto-sleeps 8 hours before encrypting (this behavior leveraged in studios running RDPGuard with alerting).