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.
Set the policy value for User Configuration -> Administrative Templates -> Microsoft Word 2013 -> Word Options -> Security 'Turn off file validation' to 'Disabled'.
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system Windows.