Title

Configuration for file validation must be enforced. (Cat II impact)

Discussion

Office File Validation helps detect and prevent a kind of exploit known as a file format attack or file fuzzing attack. File format attacks exploit the integrity of a file. They occur when someone modifies the structure of a file with the intent of adding malicious code. Usually the malicious code is run remotely and is used to elevate the privilege of restricted accounts on the computer. As a result, an attacker could gain access to a computer that they did not previously have access to. This could enable an attacker to read sensitive information from the computer's hard disk drive or install malware, such as a worm or a key logging program. The Office File Validation feature helps prevent file format attacks by scanning and validating files before they are opened. To validate files, Office File Validation compares a file's structure to a predefined file schema, which is a set of rules that determine what a readable file looks like. If Office File Validation detects that a file's structure does not follow all rules that are described in the schema, the file does not pass validation.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Word 2013 -> Word Options -> Security "Turn off file validation" is set to "Disabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\word\security\filevalidation Criteria: If the value EnableOnLoad is REG_DWORD = 1, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Word 2013 -> Word Options -> Security "Turn off file validation" to "Disabled".

Additional Identifiers

Rule ID: SV-53559r1_rule

Vulnerability ID: V-26592

Group Title: DTOO119 - Turn off file validation

Expert Comments

CCIs tied to check.

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