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What is the Attack?

A sophisticated nation-state actor gained long-term access to F5’s corporate networks and exfiltrated files from BIG-IP product development and engineering knowledge-management systems, including portions of BIG-IP source code and information about previously undisclosed vulnerabilities. F5 has released security updates and advisories covering affected products.

The stolen data could accelerate exploit development and raise the risk of targeted attacks due to the following factors:




High exposure: BIG-IP devices are widely deployed and often internet-facing.




Increased risk: Stolen source code shortens the time needed to develop exploits.




Critical role: Compromise of BIG-IP can lead to credential theft, lateral movement, and data exfiltration.

In response to F5’s disclosure, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) has issued an emergency directive

ED 26-01: Mitigate Vulnerabilities in F5 Devices | CISA.

What is the recommended Mitigation?

  • Patch immediately – Apply the latest F5 updates for BIG-IP, F5OS, BIG-IP Next for Kubernetes, BIG-IQ, and APM clients as soon as possible, as mentioned on the advisory.

    Quarterly Security Notification (October 2025)

  • Restrict access: Limit BIG-IP management interfaces to trusted networks only.

  • Monitor for anomalies: Watch for unusual admin logins, large data transfers, or new repositories.

  • Hunt proactively: Check for suspicious activity involving F5 appliances or related infrastructure.

What FortiGuard Coverage is available?

  • Active tracking: FortiGuard Labs is monitoring this campaign and will release IPS, WAF, and threat intelligence updates as exploit activity evolves.

  • IoT Device Detection: FortiGuard’s IoT Device Detection Service helps identify F5 devices across your network.

    IoT Device Detection | FortiGuard Labs

  • Incident Response: Organizations suspecting compromise can contact the FortiGuard Incident Response team for rapid containment and remediation support.