O365-OU-000012 - The warning about invalid digital signatures must be enabled to warn Outlook users.

Information

This policy setting controls how Outlook warns users about messages with invalid digital signatures.

If you enable this policy setting, you can choose from three options for controlling how Outlook users are warned about invalid signatures:
- Let user decide if they want to be warned. This option enforces the default configuration.
- Always warn about invalid signatures.
- Never warn about invalid signatures.

If you disable or do not configure this policy setting, if users open e-mail messages that include invalid digital signatures, Outlook displays a warning dialog. Users can decide whether they want to be warned about invalid signatures in the future.

Solution

Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Security >> Cryptography >> Signature Warning to 'Enabled' 'Always warn about invalid signatures'.

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_MS_Office_365_ProPlus_V3R1_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-18(1), CAT|II, CCI|CCI-001662, Rule-ID|SV-223357r961086_rule, STIG-ID|O365-OU-000012, STIG-Legacy|SV-108893, STIG-Legacy|V-99789, Vuln-ID|V-223357

Plugin: Windows

Control ID: 707361454da18c68d030bbd2d690a4a4d1720cbd9d95912bf5bac814e4d78d7d