topic Re: URL filtering Block List is not working properly in General Topics

URL filtering Block List is not working properly

SOC_CSG — Wed, 28 Feb 2018 13:35:46 GMT

Hello,

I have encountered an issue with some URL when I try to block them manually through the block list in URL filtering. I have blocked many URL for a client, but they can still access to some of those pages. The FW they are using is a PA-3020 with firmware version 7.0.10 and I have replicated the issue in my PA, which is a PA-500 with 7.1.7, so it doesn't seem an issue of the version.

It does not matter if you block the URLs with the "*." wildcard and without it, you can still access those pages, we have never had this problem trying to block any other URL, the change is applied to all profiles as other blocked webs that are effectively being blocked.

In case it helps the pages we are tryng to block are the following:

ccm.net

vidcorn.com

playmax.mx

elitegoltv.me

mamahd.com

Has anyone encountered with this kind of problem before?

Re: URL filtering Block List is not working properly

reaper — Wed, 28 Feb 2018 14:16:38 GMT

hi @SOC_CSG

you'll probably need to set up ssl decryption

some of these sites are hiding behind a certificate with a different name, example playmax uses CN ssl371663.cloudflaressl.com,

vidcorn uses sni163893.cloudflaressl.com, so you could also try blocking cloudflaressl.com as this is probably the only domain the firewall will see without ssl decryption

Re: URL filtering Block List is not working properly

jvalentine — Wed, 28 Feb 2018 15:09:13 GMT

This works properly for me with a VM-300 running PAN-OS 8.0.7. I tested elitegoltv.me and playmax.mx. Here's what I have in my blocklist:

elitegoltv.me

*.elitegoltv.me

playmax.mx

*.playmax.mx

I do not have SSL Decryption configured. Make sure you have both variants of the domain in your blocklist and test with 8.0.7.

Re: URL filtering Block List is not working properly

SOC_CSG — Wed, 28 Feb 2018 16:12:02 GMT

Hello all,

Thank you all for your replies.

We have finally blocked the pages succesfully, it was a mixed solution between @reaper and @jvalentine replies.

We were not using the wildcard and not wildcard option at the same time, thats why @jvalentine could not duplicate the issue, also for one of the pages we had to block the URL we could see and also the hidden certificate as @reaper said.

Thank you both again!

Re: URL filtering Block List is not working properly

Remo — Wed, 28 Feb 2018 16:28:06 GMT

It also depends on the client how good the URL filtering works without TLS decryption. With current browsers/os it works in most cases --> if the client sends the SNI attribute in the tls handshake, the firewall uses this url for applying the url filter policy. Without the SNI attribute the firewall has to use the CN from the certificate as there is no other cleartextvalue to apply the filter.