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StephenMcKay

Hi all,

This weekend we are making some policy changes relating to the SSL/TLS decryption of HTTPS websites. We will be adding a toggle for SSL/TLS decryption into the Threat Protection policy for all customers.

SSL Policy

This new setting will determine if Endpoints not in the Early Access Program (EAP) should decrypt HTTPs websites; it will be set to Off by default.

The settings in Global Settings will remain, it serves two purposes;

1. Set exclusions either by website category or by website name
2. Enable / Disable HTTPs decryption for devices enrolled in the EAP, it is enabled by default

SSL Global Settings

For all customers, the Global Settings page is where categories can be excluded from HTTPs decryption along with individual HTTPs exclusions. Customers not enrolled in the New Endpoint Protection Features EAP will not see the option to enable decryption for their devices

SSL Global Settings

For devices in the EAP, this explains the result of policy settings:

HTTPS Decrypt in Threat Protection policy

HTTPS Decrypt in Global Settings

HTTPS Decrypt Status on the Endpoint

ON

ON

ON

ON

OFF

ON

OFF

ON

OFF

OFF

OFF

OFF

For devices not enrolled in the EAP, when they have been migrated to the new product architecture (see https://support.sophos.com/support/s/article/KB-000043550 for details), this explains the result of policy settings:

HTTPS Decrypt in Threat Protection policy

HTTPS Decrypt in Global Settings

HTTPS Decrypt Status on the Endpoint

ON

ON

ON

ON

OFF

ON

OFF

ON

OFF

OFF

OFF

OFF

These changes will be applied if devices are added to or removed from the EAP. If an account is enrolled to the EAP, the changes will only affect devices once they are enrolled into the program.

Regards,

Stephen

  • in reply to LHerzog

    Hello, I think I understand the issue. The HTTPS Decryption Exclusions page shows items that are excluded. The per-category controls are enabled (green) when you want to exclude that category from decryption. So in your screen shot above, you've configured it to NOT decrypt the following categories:

    • Downloads
    • Health & Medicine
    • Job Search & Career Development
    • Web-based Email

    Because you've disabled the control for Finance & Investment that category WILL be decrypted.

    The logic is sensible when you think of it as activating an exclusion rather than considering it as turn decryption off.

  • in reply to LHerzog

    I wasn't able to reproduce this myself. If you drop me an SDU then I'd be happy to review the logs. If you want to review the logs yourself then you'll want to check SophosNetFilter.log and look for the ClientHello decision for these domains.

  • in reply to LHerzog

    We will check the SNI field of the ClientHello record against the exclusion list. In theory this is the hostname of the site you entered into the URL bar of your browser. We consider subdomains to be covered by the domain e.g. imagine a wildcard at the left side of whatever you add as an exclusion. Try recording some traffic with Wireshark and having a look at the ClientHello record's SNI field to see what it says.

    We can't see the full URL because at the time of the ClientHello record we haven't decrypted anything yet. And once we start decrypting we cannot stop. Hence the need to make this decision at the ClientHello.

  • in reply to LHerzog

    HI and thanks for the report. We are making some improvements to the certificate generation logic in an upcoming release that should address this issue with Firefox. The problem today starts with the fact that we regenerate our endpoint root certificates pretty regularly (usually system restarts but also a few other edge cases that also need to be addressed in that same update). That in itself isn't bad, its actually a good security practice, but in addition when we clone a website's certificate we simply copy the serial number without changing it. That actually isn't correct, and Firefox cares about that sort of thing.

  • IP and IP-Range exclusions do not work.

    As an admin you're unable to manage your devices via https://10.1.1.1:443

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