topic Re: Revoked Machine Certificate still able to Connect Global Protect Gateway in General Topics

Revoked Machine Certificate still able to Connect Global Protect Gateway

Sec101 — Fri, 20 Mar 2020 13:59:13 GMT

It appears possible to configure the firewall to be an OCSP responder to itself/clients from the posts below? Is that correct? (Specifically referring to self-signed certificates generated on the firewall) If so, is there any risk to having this service run on an external interface, in order to control/revoke machine certificates? If the need arises for a certificate revocation, is the firewall responding to itself and not letting the client connect to the portal/gateway, or is the client ultimately making that decision?

I'm finding the GP agent will still connect to the Gateway even if I have revoked a generic machine certificate used in the profile for the Gateway. The CA certificate is still good, but If I revoke the machine certificate, and it shows revoked in the firewall, the client can still connect.

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClIzCAK

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClteCAC

Re: Revoked Machine Certificate still able to Connect Global Protect Gateway

tomdevos-D09 — Thu, 25 Mar 2021 13:27:39 GMT

Same question here. How to get GP to check for revoked certs if there is no CRL or OCSP because it's self signed by the PA

Re: Revoked Machine Certificate still able to Connect Global Protect Gateway

tomdevos-D09 — Fri, 26 Mar 2021 07:58:43 GMT

@Sec101

As I had the same question I did some investigation 🙂

You need to:

- Enable OCSP checking in Device > Session => Decryption Settings

- Create an HTTP OCSP Service Management Profile under Network Profiles > Interface Management

- Create An OCSP Responder under Device > Certificate Management > OCSP Responder

- Create Client Certificates with this Responder as OCSP Responder

- make sure OCSP checking is enabled on the Certificate profile used for GP

Next to that:

Pay attention that if you revoke the certificate in the Certificate store it isn't automatically and immediatly revoked for the GP service as OCSP is cached on the FW:

To immediatly have affect you need to execute the following commands in CLI

debug sslmgr delete ocsp all (or instead of all tab comlete with your OCSP URL
debug dataplane reset ssl-decrypt certificate-status

Now the certificate will be revoked and if the client tries to (re)connect it will get that message.