OSX update and Decryption

[Sec101]

I've installed our Root CA cert in the "System" keychain, and have it marked as trusted.  I can successfully decrypt web traffic from a MAC running Mojave.  No problems there. 

The problem comes in when I try updating the OSX or even check for updates from the CLI.   

When I run "softwareupdate -l"  in terminal, In the logs on the firewall it appears to be coming through as web browsing app, and getting decrypted.  

I ran a packet capture, and it shows the client is resetting the connection after succesffuly going out to swscan.apple.com, which is not whitelisted for decryption exclusions.  Has anyone run into issues when trying to decrypt on OSX with a trusted root cert, while trying to update the operating system itself?

Guessing adding these domains to decryption exclusion is going to fix this?

[BPry · Accepted solution]

@Sec101,

Whitelist the following:

• gg.apple.com
• gnf-mdn.apple.com
• gnf-mr.apple.com
• gs.apple.com
• ig.apple.com
• mesu.apple.com
• skl.apple.com
• swcdn.apple.com
• swdist.apple.com
• swdownload.apple.com
• swpost.apple.com
• swscan.apple.com
• updates-http.cdn-apple.com
• updates.cdn-apple.com
• xp.apple.com

That should take care of the software updates and allow your clients to actually update successfully. 

[BPry · Accepted solution]

Correct. Exclude those domains from decryption and your clients should be able to check for and download updates again. 

[BPry · Accepted solution]

@Sec101,

Whitelist the following:

• gg.apple.com
• gnf-mdn.apple.com
• gnf-mr.apple.com
• gs.apple.com
• ig.apple.com
• mesu.apple.com
• skl.apple.com
• swcdn.apple.com
• swdist.apple.com
• swdownload.apple.com
• swpost.apple.com
• swscan.apple.com
• updates-http.cdn-apple.com
• updates.cdn-apple.com
• xp.apple.com

That should take care of the software updates and allow your clients to actually update successfully. 

[Sec101]

Perfect!  As always, an excellent reply!  Thank you.  When you say whitelist- you mean exclude decryption right?

[BPry · Accepted solution]

Correct. Exclude those domains from decryption and your clients should be able to check for and download updates again. 

[aaobuhov]

Hi,BPry

>Whitelist the following:

>....

Is this list actual?

 You mean path "Device -> Cert mgmt -> SSL Decription Exclusion" and add  all listed domains one by one?

Or "Policies -> Decryption -> New rule" and add rule with custom URL category.

Andrew

[BPry]

@aaobuhov,

That is the actual list yes. You can exclude these domains in either method, personally I like doing it in the decryption rulebase via a custom No-Decrypt URL category. 

[aaobuhov]

Thank you for reply 

I prefer "No-Decrypt URL category" too.

Can i summarize your list to:

*.apple.com

*.cdn-apple.com

It will be a less strict list.
Is such version possible?

Andrew

[BPry]

@aaobuhov,

You could. As you said, it would be less restrictive and potentially allow additional traffic that you otherwise could have decrypted and gained insight into. 

[aaobuhov]

Thank you, I understand.

Best wishes,
Andrew