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The warning about invalid digital signatures must be enabled to warn Outlook users.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-223357O365-OU-000012SV-223357r961086_ruleCCI-001662medium
Description
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.
STIGDate
Microsoft Office 365 ProPlus Security Technical Implementation Guide2025-03-05

Related Frameworks

1 mapping across 4 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (3) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

END-10Mobile Code
0.50
VPM-02Vulnerability Remediation Process
0.50
VPM-04Continuous Vulnerability Remediation Activities
0.50
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (4) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

CM-7Least Functionality
1.00
SC-18(1)Identify Unacceptable Code and Take Corrective Actions
1.00
SC-18(3)Prevent Downloading and Execution
1.00
SC-18(4)Prevent Automatic Execution
1.00
CCI1 mapping
CCI-001662
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 4 hops (2) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

ID.RA-08
0.50
PR.PS-02
0.50

Details

Check Text (C-223357r961086_chk)

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Security >> Cryptography >> Signature Warning is set to "Enabled" "Always warn about invalid signatures". Use the Windows Registry to navigate to the following key: HKCU\software\policies\microsoft\office\16.0\outlook\security If the value for warnaboutinvalid is set to REG_DWORD = 1, this is not a finding.

Fix Text (F-25018r442291_fix)

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