The prompt to display level 1 attachments must be disallowed when sending an item.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17602	DTOO242	SV-53957r2_rule		Medium

Description
To protect users from viruses and other harmful files, Outlook 2013 uses two levels of security, designated Level 1 and Level 2, to restrict access to files attached to e-mail messages or other items. Outlook completely blocks access to Level 1 files by default, and requires users to save Level 2 files to disk before opening them. Potentially harmful files can be classified into these two levels by file type extension, with all other file types considered safe. By default, when users attempt to send an item to which a level 1 file has been attached, Outlook warns them that the message contains a potentially unsafe attachment and that the recipient might not be able to access it. If this configuration is changed, Outlook will not display the warning when users send such items, which can cause users to lose access to important data.

Description

To protect users from viruses and other harmful files, Outlook 2013 uses two levels of security, designated Level 1 and Level 2, to restrict access to files attached to e-mail messages or other items. Outlook completely blocks access to Level 1 files by default, and requires users to save Level 2 files to disk before opening them. Potentially harmful files can be classified into these two levels by file type extension, with all other file types considered safe. By default, when users attempt to send an item to which a level 1 file has been attached, Outlook warns them that the message contains a potentially unsafe attachment and that the recipient might not be able to access it. If this configuration is changed, Outlook will not display the warning when users send such items, which can cause users to lose access to important data.

STIG	Date
Microsoft Outlook 2013 STIG	2018-09-05

Details

Check Text ( C-47960r3_chk )
Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Attachment Security "Do not prompt about Level 1 attachments when sending an item" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\security Criteria: If the value DontPromptLevel1AttachSend is REG_DWORD = 0, this is not a finding.

Check Text ( C-47960r3_chk )

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Attachment Security "Do not prompt about Level 1 attachments when sending an item" is set to "Disabled".

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

HKCU\Software\Policies\Microsoft\Office\15.0\outlook\security

Criteria: If the value DontPromptLevel1AttachSend is REG_DWORD = 0, this is not a finding.

Fix Text (F-46855r2_fix)
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Security Form Settings -> Attachment Security "Do not prompt about Level 1 attachments when sending an item" to "Disabled".