Title

Attachments using generated name for secure temporary folders must be configured. (Cat II impact)

Discussion

The Secure Temporary Files folder is used to store attachments when they are opened in email. By default, Outlook generates a random name for the Secure Temporary Files folder and saves it in the Temporary Internet Files folder. This setting can be used to designate a specific path and folder to use as the Secure Temporary Files folder. This configuration is not recommended, because it means that all users will have temporary Outlook files in the same predictable location, which is not as secure. If the name of this folder is well known, a malicious user or malicious code might target this location to try and gain access to attachments.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Cryptography -> Signature Status dialog box "Attachment Secure Temporary Folder" 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\OutlookSecureTempFolder Criteria: If the registry key exists, this is a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Security -> Cryptography -> Signature Status dialog box "Attachment Secure Temporary Folder" to "Disabled".

Additional Identifiers

Rule ID: SV-54038r1_rule

Vulnerability ID: V-17733

Group Title: DTOO269 - Attachments to Secure Temporary Folder

Expert Comments

CCIs tied to check.

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