topic SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY in General Topics

SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

mrkskhn — Mon, 13 Jan 2020 10:48:16 GMT

Hi paloalto community,

we're currently still testing ssl decryption and discovered a new error, which I can't google to find a solution.

If we're visiting the following site, we get an "ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY" error. Site: https://www.1erforum.de/

See attached our configuration and ssl information without decryption enabled.

Firmware and Specs:

PA 850 - FW 9.0.5

Settings:

Decryption disabled:

Decryption enabled:

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

BPry — Wed, 15 Jan 2020 05:09:57 GMT

@mrkskhn,

Might want to take a look at what Cipher suite the connection is attempting to make. HTTP/2 and TLS1.2 can get weird on what cipher suites do/don't cause an error.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

mrkskhn — Wed, 15 Jan 2020 08:20:33 GMT

1erforum.de is using:

The connection to this site is encrypted and authenticated using TLS 1.2, ECDHE_RSA with P-256, and AES_128_GCM.

di.fm (same error here too) is using:

The connection to this site is encrypted and authenticated using TLS 1.2, ECDHE_RSA with P-256, and AES_128_GCM.

At this point ssl decryption gets pointless, since a lot of websites are using this combination. Looks like a firmware issue?

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

BPry — Wed, 15 Jan 2020 21:43:00 GMT

@mrkskhn,

The reason that I asked what ciphers it's using is simply due to a lot of websites not actually enabling HTTP/2 correctly, but those all check out and should work perfectly fine. I'm not sure that it's actually a firmware issue, I can check to see if I run into the same issue this evening though.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

mrkskhn — Thu, 16 Jan 2020 13:21:13 GMT

That would be great. i'm looking forward to hearing from you.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

BPry — Fri, 17 Jan 2020 00:44:59 GMT

@mrkskhn,

This doesn't appear to be a software bug, the error is present in 9.0.4 and 9.1.0 as well; it also isn't an issue with the cipher suites, we can decrypt other sites perfectly fine using the same ciphers. It does however appear to be very specific to Chromium based browsers (Chrome, new Edge) as Firefox loads the site without issue.

I can't tell how this is loading in Chrome when you attempt to decrypt it, but on Firefox it uses the TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 cipher when you decrypt it when I copy the same decryption profile settings you have listed. Might want to reach out to support and see if they can point you in the right direction, but they might just call this a browser issue.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

ovel — Fri, 17 Jan 2020 12:05:22 GMT

I have the same issue on 9.1.0 VM-50

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

ovel — Fri, 17 Jan 2020 12:12:25 GMT

I have firefox 71.0 and have the same issue. The error just appears differently. The only browser is working correctly is an old IE in Win7.

From the firefox:

Your connection is not secure

The website tried to negotiate an inadequate level of security.

www.di.fm uses security technology that is outdated and vulnerable to attack. An attacker could easily reveal information which you thought to be safe. The website administrator will need to fix the server first before you can visit the site.

Error code: NS_ERROR_NET_INADEQUATE_SECURITY

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

BPry — Fri, 17 Jan 2020 14:23:33 GMT

@ovel,

I would expect this site to have issues; it defaults to using the TLS_RSA_WITH_AES_256_CBC_SHA cipher which is an inadequate cipher for HTTP/2

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

ovel — Fri, 17 Jan 2020 17:11:25 GMT

don't know, it might sound silly, but if IE has managed to negotiate with the site and is able to show its content, why PA can't do the same and use a compatible protocol to show the site content?

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

BPry — Fri, 17 Jan 2020 20:02:54 GMT

@ovel,

IE doesn't care if you are using a weak cipher suite, which is why it's working in IE but not Firefox or Chrome. The bigger issue is why the decryption process isn't negotiating to the strongest available cipher unless the site has been configured with a cipher preference that makes it utilize the strongest cipher suites by default (such as Chrome). It appears through additional troubleshooting that the firewall is using the first matching cipher, which in the case of these example sites isn't strong enough to meet the requirements of the browser.

In fairness to PAN, the HTTP/2 connection shouldn't be attempting to use a questionable cipher suite such as in the di.fm example. The vast majority of the HTTP/2 enabled websites will work perfectly fine, because the site owner is specifying the preferred order with strong to weak ciphers. In the examples listed so far the server is providing no preference order, which could be causing the firewall to negotiate to one of the weaker cipher suites being offered by the server.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

mrkskhn — Mon, 20 Jan 2020 16:57:01 GMT

Sounds like a feature which the PA team should consider? For my point of view it's more like a bug. If browsers can view the page, the PA should do it too.

For our users the current state is very bad - they will assume the page (e.g. of a customer) is not working, but instdead we have to whitelist it to exclude it from decryption.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

SStrauch — Wed, 19 Feb 2020 12:08:47 GMT

Hello together,

same issue applies for us (PANOS 9.0.5 & 9.0.6, incl. Prisma Access) and a solution would be very appreciated.

Best regards

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

accounts_swsb — Fri, 21 Feb 2020 07:32:02 GMT

The same issues also applies to the site: uebermedien.de

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

akaminer — Thu, 19 Mar 2020 17:19:21 GMT

We are seeing the same issue with https://www.dataprepu.com/ did support provided a bug id? or any info?

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

inrsys — Tue, 14 Apr 2020 19:50:27 GMT

Struggling with this as well. Found that ticking Strip ALPN on the Decryption profile helps, but doing so breaks the Safe Search functionality. When a single safe search block occurs, all traffic begins to be safe search blocked.

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

Alex_Samad — Sun, 03 May 2020 23:35:52 GMT

Lol i'm having issues with

https://microsoft.com/

sigh !

is there a bug id or a work around ?

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

SajidAliSajid — Fri, 08 May 2020 01:51:51 GMT

Solution for

https://docs.paloaltonetworks.com/pan-os/9-0/pan-os-new-features/app-id-features/http2-inspection.html

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

RSojer — Fri, 08 May 2020 07:36:02 GMT

Same issue on PA-850 with FW 9.1.2-h1
Tested with https://microsoft.com

I tried the workaround (Objects - Decryption - Decryption Profile - ENABLE/CHECK 'Strip ALPN')
successfully!

BUT to disable HTTP/2 inspection wouldn't/shouldn't be the solution I think. In future HTTP/2 sites will increase - so Palo Alto should get a solution in the software.

Palo - is there any roadmap when this issue is solved without workaround?

Re: SSL Decryption: ERR_HTTP2_INADEQUATE_TRANSPORT_SECURITY

Alex_Samad — Sun, 07 Jun 2020 00:14:16 GMT

Why is it causing an issue ?

Would be better if there was some (even any ) decrypt logs.

I spend sooo much time trying to guess why a decrypt didn't work

whats is the down side to disabling this ?