Title

Prompting behavior when closing a Level 1 attachment in Outlook. (Cat II impact)

Discussion

To protect users from viruses and other harmful files, Outlook 2007 uses two levels of security, designated Level 1 and Level 2, to restrict users' 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 a user closes an item to which a level 1 file has been attached, Outlook warns the user that the message contains a potentially unsafe attachment and that the user might not be able to access the attachment when opening the item later. (Such a sequence of events might occur when a user closes a draft message that they intend to resume editing at some future time.) If this configuration is changed, Outlook will not display the warning when the user closes the item but will still block the unsafe attachment if the user opens the message later. This functionality can cause users to lose access to important data.

Check Content

The policy value for User Configuration -> Administrative Templates -> Microsoft Office Outlook 2007 -> Security -> Security Form Settings -> Attachment Security “Do not prompt about Level 1 attachments when closing an item” will be set to “Disabled”. Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\12.0\Outlook\Security Criteria: If the value DontPromptLevel1AttachClose is REG_DWORD = 0, this is not a finding.

Fix Text

The policy value for User Configuration -> Administrative Templates -> Microsoft Office Outlook 2007 -> Security -> Security Form Settings -> Attachment Security “Do not prompt about Level 1 attachments when closing an item” will be set to “Disabled”.

Additional Identifiers

Rule ID: SV-18729r1_rule

Vulnerability ID: V-17601

Group Title:

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.