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

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L6 Presenter

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

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

 

L6 Presenter

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

The current Chome build of the user machine is:

 


Current Chorme Build (Beta): 70.0.3538.35
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L2 Linker

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

Excellent question. I pressed the Me Too button on this one. 

L1 Bithead

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

+1 - I have that same question out. 

L6 Presenter

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

I've got a support case open on this as well so we'll see what comes of it.

L6 Presenter

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

The current request from TAC is to set the "max" value on the decryption profile from "max" to TLS1.2.

 

I'm getting a change window approved for this.  We'll see what comes of it.

L3 Networker

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

Let us know what happens. 

 

Decryption method will need to change since the certificate information in TLS1.3 is hidden. There was some breif talk at ignite18 about it. I am interested to see what comes of it. 

L6 Presenter

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

It seems that the bulk of the problem happens on Chrome browsers.  So far haven't been able to reproduce the issue on anything other than Chrome (IE 11/ FF-57 build I think) also don't have a problem.

L3 Networker

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

Hi Team,

 

I have similar case on this issue where customer tried the suggestion in the Palo Alto forum to change the MAX value in the decrypt profile to TLS 1.2. However, that didn't help.

 

particularly he don't want to exclude gmail from decryption. How can we fix this?

 

Regards,

Devaraj S

L6 Presenter

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

You can't...that's the problem and something I hope Palo has an answer for soon.

 

I haven't been able to try the "max" to TLS1.2 for "max."  Like I mentioned previously though in my environment currently though the TLS downgrade issue seems to be gotten around by using a browser other than Chrome.

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