topic Re: MS Update and SSL Decryption in General Topics

MS Update and SSL Decryption

Mattk — Wed, 18 Mar 2015 16:44:03 GMT

We are having a problem with MS update and SSL decryption. Currently when a windows machine goes out to get its updates it fails. This appears to be because of the SSL decryption. I tested this by excluding one PC from encryption and it worked just fine. So my question is what are other Administrators doing to allow MS Updates to by-pass encryption?

Re: MS Update and SSL Decryption

hshah — Wed, 18 Mar 2015 17:16:09 GMT

Hi Mattk,

Please refer following document, ms-update is not supported for "SSL decryption". Please exclude it.

List of Applications Excluded from SSL Decryption

Regards,

Hardik Shah

Re: MS Update and SSL Decryption

Mattk — Wed, 18 Mar 2015 19:04:13 GMT

I saw that, but I see no where in the decryption rules where I can exclude based on Application ID. Where would I locate that?

Re: MS Update and SSL Decryption

hshah — Wed, 18 Mar 2015 19:10:10 GMT

Hi Matlk,

It can not be done throgh application ID. You can do it with most probable destination IPs of ms-update servers. You can find it from traffic logs. Let me know if that helps.

Regards,

Hardik Shah

Re: MS Update and SSL Decryption

Mattk — Wed, 18 Mar 2015 19:26:58 GMT

So if I understand what you are saying. Use the traffic logs to identify the MS Update server IP Addresses and then have the system not decrypt traffic to those IP's. Is that correct?

Re: MS Update and SSL Decryption

hshah — Wed, 18 Mar 2015 19:37:44 GMT

Hi Mattk,

That is absolutely right.

Regards,

Hardik Shah

Re: MS Update and SSL Decryption

hshah — Wed, 18 Mar 2015 19:39:27 GMT

Hi Matttk,

If URL is fixed for update server, than you can try custom URL. Let me know if you need my help with that.

Decryption profile follows URL/Custom URL category.

Regards,

Hardik Shah

Re: MS Update and SSL Decryption

daisuke — Thu, 19 Mar 2015 01:51:39 GMT

I had the same issue but now its working fine.

I was unable to access the server that is "fe2.update.microsoft.com".

This issue was due to fail decryption but it was solved by adding the url list of non-decrypt.

There is a bug for the problem that exception for ms-update is not working.

The server is not accepting the cipher suite the firewall sends, so it terminates the connection immediately before the exclude list has been populated.

So, it is not created at the timing of just sending Client Hello.

Regards,

Re: MS Update and SSL Decryption

Alex_Graser — Thu, 19 Mar 2015 07:50:04 GMT

Hi!

reading this thread I´m getting a littlebit confused. Maybay someone can spread a light on this:

Document "List of Applications Excluded from SSL Decryption" mentioned by hshah says: "These applications are added to an exclude list in each Content load so that the SSL engine will allow them to pass through, rather than trying to decrypt them."

As far as I understand it, this means that ms-update (as it is listed) should be excluded from SSL-Decryption.

So my question is: if we´re using SSL-Decryption without any custom excpetions, is access to ms-update possible or not?

If it is not possible, what should be done to enable access to ms-update?

Thanks in advice,

Alex.

Re: MS Update and SSL Decryption

bat — Thu, 19 Mar 2015 23:38:05 GMT

Hi alexander.graser

Yes the application is excluded from SSL decryption but if the SSL connection is rejected right away by server i.e. server does not send a HELLO in response to HELLO from client SSL decryption exclude list will not be checked.

To have the application excluded you will have to create a no-decrypt policy for URL update.microsoft.com, *.update.microsoft.com

Hope it helps!

Re: MS Update and SSL Decryption

Alex_Graser — Fri, 20 Mar 2015 08:07:02 GMT

Thank you bat,

I think now it´s a littlebit more clear to me.

So the exclusion of ms-update from SSL-Decryption does not work with Windows-Update.

Does anyone know if the no-decrypt policy for URL update.microsoft.com and *.update.microsoft.com is working for all Windows Versions - ie Win7, Win8, Win8.1 and Win10-Beta?

Alex.

Re: MS Update and SSL Decryption

rrajendran — Fri, 20 Mar 2015 23:42:44 GMT

Hi Alex,

Yes, I have tested and it is working. However, I am not sure about Win10-Beta version.

Regards,

Ramya

Re: MS Update and SSL Decryption

Alex_Graser — Mon, 23 Mar 2015 14:03:03 GMT

Thanks, Ramya!

I´ve added update.microsoft.com and *.update.microsoft.com to our no-decrypt policy and it seems to work for me, too.

Greetings,

Alex.