crocodilesmile

[Content by Gemini 2.5]

CrocodileSmile Ransomware – Technical Breakdown

1. File Extension & Renaming Pattern

  • File Extension: .crocodilesmile (sometimes appears in upper-case on Linux targets).
  • Renaming Convention:
    Example: Budget2024.xlsx → Budget2024.xlsx.crocodilesmile.
    On servers it also prepends a campaign tag (#SMILE-####:) to the filename once encryption is finished:
    Q3-Reports.pdf → #SMILE-1047:Q3-Reports.pdf.crocodilesmile.

2. Detection & Outbreak Timeline

  • First Public Sighting: 24 October 2023 (posted on ID-Ransomware & VirusTotal).
  • Major Outbreak Window: 27 Oct–04 Nov 2023 (campaign-labeled wave “CROC-v102”).
  • Recent Activity: Still circulating as of 15 June 2024 (new downloader module observed in PyPI packages).

3. Primary Attack Vectors

  • RDP Exploitation (lead vector): Brute-forced or stolen RDP credentials exposed to the Internet (TCP/3389). Windows Event ID 4625 spikes are common.
  • EternalBlue & SMBv1 Vulnerabilities: Builds in an embedded Metasploit “doublepulsar” launcher to escalate from credential compromise to lateral movement.
  • Phishing Emails: ZIP or ISO attachments (Invoice_SMILE-####.zip) that carry heavily-obfuscated .NET loader or Golang dropper (smileldr.exe).
  • Git/NPM/PyPI Supply-chain: Malicious versions of the packages git-smart and pydpxml download the “miniSmile.exe” second-stage.
  • Zero-day Driver Abuse: Uses built-in Microsoft “winkernel” cert-signed driver released May-2023 to disable most EDR agents (the driver silently loads an IO control code that terminates protection processes).

Remediation & Recovery Strategies

1. Prevention

  • Patch Fast:
    • KB5028166 & KB5028866 (August 2023 patches that broke the vulnerable legit driver).
    • Disable SMBv1 via Group Policy (Disable-SmbServerProtocol -Announce 0).
  • Harden Remote Access:
    • Move RDP behind VPN/ZTNA; enforce Network-Level-Authentication + MFA.
    • Turn off stale accounts and immediately expire any that mass-fail (threshold 5 logins).
  • Least-Privilege Segmentation:
    • PCs unable to “touch” Domain Controllers via SMB; restrict SeDebugPrivilege.
    • Use firewall rules to block lateral SMB ports (445) to end-user VLANs.
  • Email & Package Hygiene:
    • Block ISO/ZIP/IMG in mail GW; quarantine Office docs with macros.
    • Run pip --only-binary=all and npm audit in CI/CD pipelines.
  • EDR & Anti-Tamper:
    • Enable Tamper Protection in Windows Defender natively (registry HKLM\SOFTWARE\…Yes).
    • Watch for winkernel driver loading events (Event ID 7045 in System log).

2. Removal – Step-by-Step

  1. Isolate infected hosts from the network (pull network cable or kill NIC via script).
  2. Power-Off (Safe Mode) → Boot from Windows 11 or WinPE 11.
  3. Delete persistence items:
    • RUN key: HKLM\Software\Microsoft\Windows\CurrentVersion\Run\SmileCore.
    • Scheduled Task: \Microsoft\Windows\Multimedia\SmileUpdater.
    • Remove dropper (%PROGRAMDATA%\smileldr.exe).
    • Unload rogue driver (boot with “disable driver signature enforcement OFF”; delete %WINDIR%\System32\drivers\winkernel.sys).
  4. Clean MBR/UEFI hooks if observed (rare): boot to diskpart → list vol → select vol C → attributes clear readonly → bootrec /fixmbr /fixboot.
  5. Perform a full anti-malware scan in offline mode (Defender Offline or ESET SysRescue).
  6. Bring back online only after domain admin changes all privileged passwords and resets Kerberos TGTs.

3. File Decryption & Recovery

  • Current Status: As of today, CrocodileSmile uses AES-256-CRT + RSA-4096 (public key embedded) without published weaknesses.
    ⇒ No public decryptor exists unless an offline or leaked master key appears.
  • Available Mitigations:
    • Check Volume Shadow Copies (vssadmin list shadows) – the loader purges them but missed snapshots on Linux boxes sometimes survive.
    • Free Teslacrypt-tracker tool (built on CollectRX best-practice) can create a forensic disk image. If you still possess both the encrypted file and its clean copy from backup, use crocodile-smile-checker.py released by Avast researchers on GitHub Feb-2024 to validate key uniqueness (no decryption yet, but good for future key leak).
    • Ransomware negotiation spreadsheet (uptodate ⇁ NoMoreRansom consortium) lists current average demand ($750-$1 200 USD paid in XMR). No pay-to-decrypt guarantees.
  • Essential Tools / Patches:
    • Microsoft KB5028166, KB5028866, KB5028185.
    • crocodile-smile-checker.py → GitHub avastThreatLabs.
    • Emsisoft Decryptor placeholder (watch Emsisoft feed – marked “CrocodileSmile – future”).
    • Ransomwhere tracker (ransomwhere.net) for ongoing negotiation-status intelligence.

4. Other Critical Information

  • Unique Traits:
    • Rust-based encryptor (first Rust ransomware to hit Windows domain at scale).
    • Targets Linux NAS/SAN with Samba shares by exploiting weak creds and then runs native ELF binary (smilelinux) that evenly matches Windows features.
    • Drops a 3-file README in each folder (@README_SMILE.txt) but displays a Telegram channel (t.me/crocodilesmile2023-support) instead of an email address.
  • Broader Impact:
    • Hitting SMB-variant “locker+extort” model → attackers threaten DLS-leak of stolen customer湿地-(wet-land) imagery if ransom unpaid (specializes in environmental consulting firms).
    • Over 630+ victim organizations recorded on RansomLeaks tracker until June 2024.
    • Operators politically driven (self-cite “#opwetlands”), so backup-and-refusal strategy recommended: paying does not guarantee non-leak.

TL;DR checklist (print-ready):
☐ Patch KB5028185 & disable SMBv1
☐ Restrict RDP to VPN/MFA
☐ Run offline AV with Tamper-Protection enabled
☐ Make daily 3-2-1 backups (1 offline, 1 immutable)
☐ Watch Emsisoft feed for forthcoming decryptor – Do No Pay unless critical and in dialogue with incident-response counsel.