Title

The encryption type for password protected Open XML files must be set. (Cat II impact)

Discussion

If unencrypted files are intercepted, sensitive information in the files can be compromised. To protect information confidentiality, Microsoft Office application files can be encrypted and password protected. Only users who know the correct password will be able to decrypt such files. Since some encryption types are less secure and easier to breach, Microsoft Enhanced RSA and AES Cryptographic Provider, AES-256, 256-bit should be used when encrypting documents.

Check Content

Verify the policy value for User Configuration >> Administrative Templates >> Microsoft Office 2013 >> Security Settings "Encryption type for password protected Office Open XML files" is set to "Enabled (Microsoft Enhanced RSA and AES Cryptographic Provider, AES 256,256)". Use the Windows Registry Editor to navigate to the following HKCU\Software\Policies\Microsoft\Office\15.0\common\security If the value 'OpenXMLEncryption' is REG_SZ = "Microsoft Enhanced RSA and AES Cryptographic Provider, AES 256,256", this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Office 2013 -> Security Settings "Encryption type for password protected Office Open XML files" to "Enabled (Microsoft Enhanced RSA and AES Cryptographic Provider,AES 256,256)".

Additional Identifiers

Rule ID: SV-228548r508020_rule

Vulnerability ID: V-228548

Group Title: SRG-APP-000231

Expert Comments

CCIs tied to check.

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