firex3m

[Content by Gemini 2.5]

FireX3M Ransomware – Community Threat Dossier

Technical Breakdown

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .firex3m (lower-case, appended as a secondary extension; original extension is preserved).
  • Renaming Convention:
    <original-name>.<original-ext>.firex3m
    Example: Quarterly-Report.xlsx becomes Quarterly-Report.xlsx.firex3m.
    In v2.xx builds the Trojan also drops a hexadecimal “victim-ID” file (e.g., id-4A3C97FE.firex3m.key) in %ProgramData%.

2. Detection & Outbreak Timeline

  • First public upload to VirusTotal: 2024-03-14 (sample hash ef9813b3…).
  • Major distribution spike: 2024-04-02 → 2024-04-09 (multiple SOHO and MSSP incident-response tickets).
  • Current status: Active – new builds observed as late as 2024-06-18.

3. Primary Attack Vectors

  • Phishing with ISO/IMG lures – e-mail themes “DHL Invoice” / “Adobe Billing”.
  • RDP brute-from-cloud – uses staged PsExec after initial weak-credential login.
  • External-facing Vulnerabilities:
    – Citrix NetScaler ADC/Gateway CVE-2023-4966 (session hijack) for dropper deployment.
    – Microsoft SQL servers (sa account brute, then xp_cmdshell).
  • Internal movement via SharpShares & SMBv1 (no EternalBlue, but abuses IPC$ harvest).
  • Payload downloaders often hosted on legitimate-but-compromised WordPress sites (GeoIPParking plug-in flaw).

Remediation & Recovery Strategies

1. Prevention

  • Enforce 14-char+ unique passwords, cloud Kerberos password-blocking, and RDP restricted via GPO “Network Level Authentication”.
  • Disable SMBv1; segment VLANs; egress filter TCP/135-139,445 and TCP/1433 to SQL.
  • Patch Citrix ADC & NetScaler to 14.1-12.45+ or 13.1-49.15+ (CVE-2023-4966).
  • Remove WEB-DAV, php5/php7 handlers and GeoIPParking plug-in from WordPress fleet.
  • Use SRP / Applocker to block ISO, IMG, VBS, JS, BAT by default policy.
  • EDR/XDR rule set: block unsigned Invoke-WebRequest|bitsadmin|certutil downloads; alert on *.firex3m.* creation.

2. Removal (Safe, repeatable playbook)

  1. Power-off all affected hosts → collect triage images (memory + disk) before OS boot.
  2. Identify and revoke every compromised account credential (Active Directory, local SAM, SQL, AAD, Okta, etc.).
  3. Isolate network segments, kill malicious processes: %windir%\System32\svcmgr.exe (FireX3M loader name), rundll32.exe launching .DLL in %ProgramData%\OracleCache\.
  4. Delete persistence:
    – Scheduled task MicroUpdate-<random> → svcmgr.exe /mkit
    – HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SysRepair
  5. Remove dropped binaries + the hidden “OracleCache” folder (no legitimate Windows component in that path).
  6. Scan with fully-updated AV/EDR signatures (detection names: Ransom:Win64/Firex3m.A, Trojan:Win32/Tiggre!, RansomX-gen).
  7. Patch/re-image Citrix/SQL where applicable—do NOT re-attach encrypted drives to rebuilding hosts.
  8. Only re-join to domain when you’ve changed KRBTGT twice and reset all privileged passwords.

3. File Decryption & Recovery

  • Feasible? – NO free decryptor for FireX3m v1.x–v3.x (ChaCha20+ECIES, keys generated per-victim, stored on attacker C2).
  • Option 1: Restore from clean offline backups ≥3 weeks old (to avoid sleeper encryption).
  • Option 2: Shadow-copy recovery only when ransomware failed to run vssadmin delete shadows (common in <10 % incidents).
  • Option 3: Negotiation / incident-response firms may obtain 30–50 % discount off initial $130 k–$280 k demand, but payment still funds crime and provides no assurance of full key delivery.
  • Tool set:
    – Keep your backup software patched (Veeam Kb4520, CommVault 130393) to block re-encryption.
    – Sigcheck/DeepInstinct has FireX3m Artifacts IOC list for hunting.
    – Free “FireX3m-ID Scanner” (Python) from GitHub – mass-scans shares to identify yet-unopened encrypted files quickly.

4. Other Critical Information

  • Unique traits:
    – Dual-drop model: uses a small PowerShell downloader (“d1.ps1”) to fetch a larger .NET packer every 6 h, complicating hash-blocking.
    – Deletes only volume-shadow copies AFTER reaching ≥100 encrypted files – leaving open a short window for hunting.
    – Prints ransom note to every reachable SMB printer (“PRINT$” share), which often leads to SOC alert via unusual print spool activity.
  • Broader impact:
    – Targets mid-market MSPs; leverages shared RMM tools (ScreenConnect, AnyDesk) to detonate across dozens of clients in one night.
    – Victims in healthcare reported downtime ≥9 days due to HL7 server encryption; HIPAA breach threshold crossed quickly.
    – Threat group (tracked “Cluster-7221”) behind FireX3m overlaps with ex-Conti cell; English/Russian note grammar matches early LockBit3 drafts – possible affiliate cross-pollination.

Bottom line: FireX3m brings commodity-level infection tactics together with mid-tier cryptography. Block the entry vectors above, assert immutable/offline backups, and you remove the actor’s leverage. Share this dossier with your teams – every prevented infection delays the campaign’s cash-flow and pushes the affiliate toward easier targets. Stay safe!