The encryption type for password protected Open XML files must be set.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-17619	DTOO189	SV-52726r2_rule	ECSC-1	Medium

Description
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.

Description

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.

STIG	Date
Microsoft Office System 2013 STIG	2015-06-18

Details

Check Text ( C-47054r3_chk )
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)". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\common\security Criteria: If the value OpenXMLEncryption is REG_SZ = "Microsoft Enhanced RSA and AES Cryptographic Provider,AES 256,256", this is not a finding.

Check Text ( C-47054r3_chk )

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)".

Procedure: Use the Windows Registry Editor to navigate to the following key:

HKCU\Software\Policies\Microsoft\Office\15.0\common\security

Criteria: If the value OpenXMLEncryption is REG_SZ = "Microsoft Enhanced RSA and AES Cryptographic Provider,AES 256,256", this is not a finding.

Fix Text (F-45651r2_fix)
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)".