WAF: Managed Rule Set Exception for JSON Body

metalheart 331 Reputation points
2022-10-24T11:57:20.883+00:00

I am getting several MS managed rule violations from WAF for a legitimate request that posts JSON data to a web API endpoint:

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What is a good approach to add an exclusion for this request? My usual approach with POST form data based on the POST argument name doesn't work here, nor can I filter by the request header/cookie/query string args name:

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Azure Front Door
Azure Front Door
An Azure service that provides a cloud content delivery network with threat protection.
498 questions
Azure Web Application Firewall
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  1. ChaitanyaNaykodi-MSFT 17,976 Reputation points Microsoft Employee
    2022-10-24T16:53:41.253+00:00

    @metalheart ,
    Thank you for reaching out.

    If I have understood correctly, the JSON request body in your web request is getting blocked by your WAF. You tried adding the Request body post args name exclusion rule but it did not work.

    I think you should be able to exclude above JSON request body by adding a Request body JSON args name instead. You can follow this documentation here to try and add this exclusion rule,

    Hope this helps! Please do let me know if this exclusion rule does not work in your case. Thank you!