Symptoms

The number of the signatures per virtual server is not limited. This can result in a very large number of generated signatures during sophisticated attacks that use changing patterns. After a time, when a system experiences a number of attacks, the list of generated signatures can be too long.

Impact

High CPU utilization when mitigating. Overloaded GUI signatures screen.

Conditions

-- Sophisticated attacks that use changing patterns. -- System experiences a large number of attacks.

Workaround

Manually remove old / not-often-used signatures.

Fix Information

The system now limits the number of signatures per virtual servers, and optimizes per-signatures operation.

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips