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V-251865

CAT II (Medium)

Read signed email as plain text must be enforced.

Rule ID

SV-251865r961863_rule

STIG

Microsoft Outlook 2016 Security Technical Implementation Guide

Version

V2R4

CCIs

CCI-000366

Discussion

Outlook can display email messages and other items in three formats: plain text, Rich Text Format (RTF), and HTML. By default, Outlook displays digitally signed email messages in the format which they were received.

Check Content

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Preferences >> E-mail Options "Read signed e-mail as plain text" is set to "Enabled".

Procedure: Use the Windows Registry Editor to navigate to the following key: 

HKCU\Software\Policies\Microsoft\Office\16.0\outlook\options\mail

Criteria: If the value ReadSignedAsPlain is REG_DWORD = 1, this is not a finding.

Fix Text

Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Preferences >> E-mail Options "Read signed e-mail as plain text" to "Enabled".