TLS 1.3 is Coming - How to deal with it????

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TLS 1.3 is Coming - How to deal with it????

L6 Presenter

My security counter parts came to me letting me know that in Chrome version 70.X+ TLS 1.3 will be turned on by default.  This appears to be causing problems in our current firewall deployment:

 

A/P HA-par 5220s running 8.0.10 (soon to be 8.0.12).

 

It looks like Google has released an article describing what's going on:

 

https://www.chromium.org/Home/tls13

 

In this article it highlights how Cisco FirePower devices can be configured to avoid issue.  Does anyone know how to correct this in Palo?

 

 

Here is the error the users get (TLS1.3 Downgrade detected)

 

TLS_Error.png

 

 

 

This is the traffic log for the user traffic.  "Webmail" access is allowed, and we're doing SSL decryption.

 

TLS_1.3.PNG

 

25 REPLIES 25

Hello All,

The link to the google groups article fixes the issue as it tells Chrome to disable the 1.3 variant.

 

Just paste the following into the chrome browser address field and it should bring it up, then change the setting to 'Disabled'. You will have to restart your browser.

 

chrome://flags/#tls13-variant

 

Cheers!

Desabling the 1.3 variant works on my PC, but i'm not sure how I would go about deploying this workaround.  

 

I don't have the option to disable 1.3 variant in my Chrome GPO, at least by that name.

 

Any ideas in that regard?

Update on this issue:

 

"We are aware of two vendors whose products have this bug: Cisco and Palo Alto Networks, although there may be more. We reported the issue to Cisco in December 2017. They released the fix this past August and have published an advisory. Palo Alto Networks recently discovered the issue on their devices and are planning to release PAN-OS 8.1.4, PAN-OS 8.0.14, and PAN-OS 7.1.21 to fix this, tentatively by Nov 30th."

 

Full link: 

 

https://www.ietf.org/mail-archive/web/tls/current/msg27066.html

 

I updated our firmware last night to 8.1.4 and the issue has gone away

PAN-OS 8.0.14 and 8.1.4 will support TLS 1.3.

 

 

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