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How to fix DLP profile is not blocking credit card info when outlook desktop app is using HTTPS

The article describes that DLP profile does not work as expected for the CCN body message if the Outlook desktop app sends traffic using HTTPS protocol.

Scope

Any FortiOS.

Solution

Configure Outlook to use MAPI over HTTP or RPC over HTTP protocols and ensure that the data transferred is not exclusively over HTTPS. The FortiGate needs to have enabled Mapi-over-http in the ssl inspection profile:

config firewall ssl-ssh-profile
edit deep inspection
set mapi-over-http [disable|enable]
end

It has been confirmed that a functional version of the Outlook desktop app is Version 2405, Build 16.0.17628.20006. Newer versions do not support mapi protocol for traffic from the Outlook desktop app.

Use the following debugs command to determine if the Outlook desktop app is using MAPPI or HTTPS:

diag debug reset
dia sys scanunit debug all
diag debug enable
  1. Run the DLP test, wait until it fails, and check the logs.
  2. Stop the debugs: diag debug disable.
  3. Save the output obtained in the CLI.

Execute the WAD debugs:

diag wad debug enable category all
diag wad debug enable level verbose
diag wad debug enable cate http
diag wad debug enable cate mapi
diag wad debug enable leverl verb
diagnose debug console timestamp enable
dia de ena

Repeat the steps mentioned above from 1 to 3.

If ensure to know how to interpret the debugs obtained, open a TAC ticket. Reach Microsoft support to get additional assistance on how to configure the recent Outlook desktop app if it is possible.