topic Re: OSX update and Decryption in General Topics

OSX update and Decryption

Sec101 — Mon, 09 Sep 2019 20:27:35 GMT

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?

Re: OSX update and Decryption

BPry — Tue, 10 Sep 2019 01:48:07 GMT

@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.

Re: OSX update and Decryption

Sec101 — Tue, 10 Sep 2019 14:01:08 GMT

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

Re: OSX update and Decryption

BPry — Tue, 10 Sep 2019 14:04:37 GMT

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

Re: OSX update and Decryption

aaobuhov — Wed, 18 Mar 2020 08:18:13 GMT

Hi,BPry

>Whitelist the following:

>....

Andrew

Re: OSX update and Decryption

BPry — Wed, 18 Mar 2020 13:08:13 GMT

@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.

Re: OSX update and Decryption

aaobuhov — Wed, 18 Mar 2020 13:17:06 GMT

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

Re: OSX update and Decryption

BPry — Wed, 18 Mar 2020 13:20:18 GMT

@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.

Re: OSX update and Decryption

aaobuhov — Wed, 18 Mar 2020 13:30:03 GMT

Thank you, I understand.

Best wishes,
Andrew