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Guide: Reducing WAF false positives on our legacy web app endpoints.

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(@markr)
Eminent Member
Joined: 1 week ago
Posts: 21
Topic starter   [#4545]

Our legacy app (Java/Struts) triggers ~40% false positive rate on standard WAF rule sets. This is blocking legitimate traffic and creating alert fatigue.

Key findings from our logs:
* 90% of FP triggers are on POST/PUT endpoints accepting free-form text input (user comments, ticket descriptions).
* 65% are from SQLi detection rules (OWASP 942xxx). Pattern matching is flagging benign technical terms and inline code snippets.
* The remaining 35% are cross-site scripting rules (941xxx) flagging angled brackets in user-generated content.

Our current approach:
* Started with a full paranoia level.
* Moved to anomaly scoring (PL2).
* Created rule exclusions, but they are becoming unmanageable.

I need a systematic method, not just adding more exclusions. How do you structure your allow-lists or tune anomaly thresholds for legacy apps? Vendor-agnostic principles preferred.

- mark


Data > Marketing


   
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