topic Re: How to Block a Specific HTTPS Site with URL Filtering in General Topics

How to Block a Specific HTTPS Site with URL Filtering

rjdahav163 — Tue, 08 May 2018 16:03:04 GMT

If I want to use URL Filtering Profile to block a particular "https" website (for ex, youtube.com) do I compulsorily need a decryption profile as well?

This question is partly answered here:

https://live.paloaltonetworks.com/t5/Configuration-Articles/How-to-Block-a-Specific-HTTPS-Site-with-URL-Filtering/ta-p/53840

But the example is specific to a sub-URL. I want to know for any HTTPS Website.

Thanks and Regards,

Re: How to Block a Specific HTTPS Site with URL Filtering

Raido_Rattameister — Tue, 08 May 2018 19:39:28 GMT

If traffic is encrypted then all that Palo sees is name on the certificate and it assumes application/website based on that.

For example in case of Google it is *.google.com

In case of SSL traffic HTTP GET goes inside encrypted payload and without decrypting Palo does not see it.

As a result Palo can't distinguish if you go to maps.google.com or www.google.com etc.

Also if you want to block specific Youtube videos you need decryption to see full URL user tries to access.

Re: How to Block a Specific HTTPS Site with URL Filtering

Remo — Tue, 08 May 2018 23:20:20 GMT

Actually it is possible to have URL filtering configured without TLS decryption, because the client sends the hostname of the website where it wants to connect in the TLS handshake. This part of the connection is not encrypted so Palo is able to filter based on that value.

Re: How to Block a Specific HTTPS Site with URL Filtering

Raido_Rattameister — Wed, 09 May 2018 05:14:24 GMT

You are right. Palo can use data in SNI that is sent by the client.