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Add a CA for _Burp_ Pro to trust. "Received fatal alert: unknown_ca"

Bertuglia, | Last updated: Aug 09, 2021 07:05PM UTC

I have a uniq signing CA that I want Burp Pro to trust. I keep getting "Received fatal alert: unknown_ca" for services that are signed by it. I've tried to use keytool to add to _EVERY_ file that looks like cacerts, but that seems to have no affect at all. 1. Which file(s) is Burp Pro using for CA storage? 2. What is the correct process for adding a new CA for Burp Pro to trust for forward connections? Env: MacOS 10.15.7 Please note: I do not need to add the Burp CA to my browser's trust store. I've done that, and it works correctly.

Bertuglia, | Last updated: Aug 09, 2021 09:17PM UTC

Curl helped and tcpdump helped. Upstream servers send this error back to clients when the client certs offered, (from Burp in this case) aren't aren't signed by a CA trusted by the server. The error is just passed back down to the client by Brup from the server.

Hannah, PortSwigger Agent | Last updated: Aug 13, 2021 10:29AM UTC