09-09-2020 02:17 PM
I don't know if it's the same event, but I've previously received the following response from Palo Alto support, so I'll just state it as it is I have not checked this way to see if the sites noted will be able to connect, and I have downgraded and used HTTP/2 by disabling ALPN. Therefore, if you have implemented the following solution, I would be happy to let you know here.
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When a Client Hello is sent from the client, PANOS receives this Client Hello and sends it to
Send to the web server.
When PANOS sends the Client Hello, it inserts a Cipher Suite, depending on the settings in the decryption profile, and sends it to the WEB server.
The web server receives the Client Hello sent by PANOS and inserts the
Responds to Cipher Suite in the order in which it is presented, with the Cipher Suite supported by the web server.
However, it should have responded with the highest-strength Cipher Suite.
Because the web server responded in the order in which the Cipher Suite was presented, RFC 7540 for HTTP/2
"9.2.2. TLS 1.2 Cipher Suites" used a low strength Cipher Suite that should not be used.
As a result, we received a Server Hello sent from the web server and the client received a FIN
The packet was sent and the traffic was terminated.
Therefore, we have determined that it is a server/client browser issue.
Based on the above, we would like to provide two solutions:
1. In the decryption profile settings, please try to use Cipher Suite (registered in RFC 7040)
Exclude "Appendix A. TLS 1.2 Cipher Suite Black List"
2. use PANOS 10 or higher
(In PANOS 10.0, the order in which Cipher Suite is presented has been changed.)
