The default message format must be set to use Plain Text.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-251866 | DTOO314 | SV-251866r811197_rule | CCI-000366 | medium |
| Description | ||||
| Outlook uses HTML as the default email format. HTML format poses a security risk by embedding information into the email itself, which could allow for release of sensitive information. If a user attempted to insert an HTML link into an email message, the link itself may direct to a malicious website. By sending emails in HTML format, the recipient could be subject to becoming infected by the malicious website. | ||||
| STIG | Date | |||
| Microsoft Outlook 2016 Security Technical Implementation Guide | 2022-03-11 | |||
Details
Check Text (C-251866r811197_chk)
Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Mail Format >> Internet Formatting >> Message Format "Set message format" is "Enabled: Plain Text".
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 EditorPreference is REG_DWORD = 65536 (dec), this is not a finding.
Fix Text (F-55280r811188_fix)
Set the policy value for User Configuration >> Administrative Templates >> Microsoft Outlook 2016 >> Outlook Options >> Mail Format >> Internet Formatting >> Message Format "Set message format" to "Enabled: Plain Text".