October 17, 2025 1 Minute Read

On August 9, F5 discovered that multiple systems were compromised by what it is calling a "highly sophisticated nation-state threat actor" who maintained "long-term, persistent access to certain F5 systems". These included the BIG-IP product development environment and engineering knowledge management platform. That access allowed for the exfiltration of portions of F5's BIG-IP source code as well as information about undisclosed BIG-IP vulnerabilities F5 was working on.

F5 did not discuss the length of the dwell time the threat actors maintained, or how long containment took. However, F5 notes several important facts:

• It has not seen any new unauthorized access or returning actors since they initiated containment.
• There were no undisclosed critical or RCE vulnerabilities leaked.
• There is no evidence of modified source code or to their software supply chain.
• There is no evidence of Zero-Day exploitation (a risk due to the leaked source code).

While this compromise was discovered in early August, it wasn't publicly disclosed until October 15. F5 said the delay was requested by the US DOJ. Also, US CISA issued an emergency directive requiring agencies to inventory all F5 products as well as their current network access.

F5 users are recommended to apply any and all current updates. It's also important to note that this incident only represents potential risk. Exploitation would require the threat actors to discover a vulnerability in the source code, weaponize it, and then exploit it. Until or if that occurs, no indicators of compromise (IoCs) will be available.

To properly prepare to that potential circumstance, we recommend that organizations:

• Inventory all F5 products, ensure they are patched, and not accessible from the public Internet.
• Revisit your incident response policies to make sure they are current and have been recently practiced.
• Monitor F5 news for any mention of exploit code or Proof of Concept code. You may want to set up keyword alerts in Google and your Social Networks for this.
• Log and monitor all access to and from your F5 products for anomalous behavior.

Trustwave SpiderLabs will continue to monitor this situation for any new developments.

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