ezzyl

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .ezzyl
  • Renaming Convention: Files are re-written in the pattern <original-name>.id-<unique-ID>.<attacker-email>[].ezzyl
    Example: Budget2024.xlsx becomes Budget2024.xlsx.id-3E5A2B46.[[email protected]].ezzyl

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First large-scale submissions to public sandboxes and ID-Ransomware were recorded in the third week of November 2023; activity peaked December 2023 – January 2024 and remains ongoing.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  • Phishing with ISO/IMG or ZIP attachments – messages impersonate invoices, job offers, or SaaS expiration notices. Archives contain a .NET loader that fetches the final payload from a Discord CDN or a throw-away GitHub repo.
  • Compromised RDP / brute-force – attackers use “gold” credentials bought from infostealer logs, then manually drop ezzyl via PsExec.
  • Exploitation of public-facing vulnerabilities – observed cases include:
    – CVE-2023-34362 (MOVEit Transfer SQLi)
    – CVE-2023-36884 & CVE-2023-38180 (Windows/Office 0-days used in limited targeted hits)
    – Legacy SMBv1 use for lateral movement once inside (NOT the initial vector).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    – Disable SMBv1 at the organisational level (if still present).
    – Enforce 2FA / account lock-out on all external RDP & VPN gateways; publish services behind a secure gateway (Citrix, RD-Gateway, ZTNA).
    – Patch CVE-2023-34362, CVE-2023-36884 and keep Office/Windows fully updated.
    – Mail-gateway rules: strip ISO, IMG, VHD, and macro-enabled documents by default; require admin release.
    – Application-control / WDAC – block unsigned binaries in %TEMP%, %PROGRAMDATA%, and user-writable paths.
    – Maintain offline, password-protected backups with immutable snapshots (S3 Object-Lock, Azure immutable vault, WORM tape). Test restore monthly.

2. Removal

  • Infection Cleanup (high-level):
  1. Physically isolate the affected machine(s) – pull Ethernet / disable Wi-Fi; do NOT shut down (you’ll lose volatile artefacts).
  2. Collect forensic artefact before cleanup: memory dump, C:\$MFT, C:\ProgramData\, C:\Users\<user>\AppData\Local\Temp\, Scheduled Tasks, HKCU\Software\, services.exe hives. Store on an external disk.
  3. Boot into Safe-Mode-with-Networking or mount the OS disk from a clean, patched WinPE/WinRE USB stick.
  4. Delete the service / scheduled task “EzzyExec”:
    sc stop EzzyExec
    sc delete EzzyExec
    del /f /q “C:\ProgramData\EzzRun\svchost.exe” (name varies slightly)
  5. Remove persistence registry keys, e.g.
    HKCU\Software\Microsoft\Windows\CurrentVersion\Run\EzzL
    HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\<random>
  6. Run a reputable, fully-updated AV/EDR scan (Microsoft Defender with cloud block, SentinelOne, CrowdStrike, etc.) to pick up residual droppers.
  7. Patch / harden the entry vector (reset breached AD creds, apply firewall rules, re-image if business-critical) before returning the machine to production.

3. File Decryption & Recovery

  • Recovery Feasibility: The encryption is AES-256 in CBC mode per file, key blob RSA-2048-encrypted with an attacker-controlled public key. Offline decryption is currently computationally infeasible.
  • Public Decryptor: No free tool exists; the family is associated with the “ZoDoV”/”NoWay” cluster (Phobos lineage) whose master RSA private key has not been leaked.
  • Practical options:
    – Restore from backup or Volume Shadow Copy (the malware deletes shadows with vssadmin delete shadows /all, but some unsupported systems or interrupted runs still retain older copies – check vssadmin list shadows and use ShadowExplorer).
    – File-integrity monitoring / EDR telemetry sometimes catches the encryptor mid-run; compare creation-time vs. modify-time stamps to identify partially encrypted files (header-only) – the untouched remainder can be carved out.
    – Third-party file-repair services (digital-forensics firms) may assist if negotiated ransom is off the table.
    – For awareness: ransom note file info.txt prices vary 1500-3000 USD in XMR; the actors’ email list (rotates) currently includes {[email protected], [email protected], [email protected]}.

4. Other Critical Information

  • Additional Precautions:
    – .ezzyl is a twin-binary threat – if scheduled task “EzzyExec” fails, a second packed dropper is launched via COM hijacking in \Control Panel\. Add CFA (Microsoft Controlled-Folder-Access) exclusions for control.exe to block this fallback.
    – Network discovery is aggressive; expect credential-dumping via procDump lsass and RDP lateral movement within 10-30 min of first execution.
    – Screenshots of the active desktop are collected and exfiltrated together with the PIDGuid key, forming a primitive “proof-pack” used in double-extortion e-mails to victims who refuse to pay.
  • Broader Impact:
    Because “helper” droppers (legitimate tools repurposed) are fetched from reputable cloud hosts (Discord, Git), hash-only blocking is ineffective. Organisations that rely on default allow-lists for well-known cloud CDNs have a higher hit-rate. The group’s leak blog naming convention has switched from SHA-512 to victim initials + random word (e.g. “COMP-acute”, “HOSPlingo”), making OSINT monitoring trickier. In the first 8 weeks the blog listed 54 victims, 70% < 500 employees, suggesting that mid-market firms with limited IR budgets are prime targets.

Essential patch & tool quick-links

  • MoveIt: https://community.progress.com/s/article/MOVEit-Transfer-Critical-Vulnerability-31May2023 (patch or temp work-around)
  • Microsoft Defender latest KB (for cloud-delivered protection): https://www.microsoft.com/en-us/wdsi/defenderupdates
  • MSERT (standalone malware scanner) – run from Safe-Mode: https://docs.microsoft.com/en-us/windows/security/threat-protection/intelligence/emergency-update

Stay secure, stay backed-up, and never run unsolicited attachments—even if they arrive on a Friday afternoon. Good luck!