Windows must be configured to block application execution if certificate server status is unavailable.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-7065	APPNET0050	SV-7448r2_rule	DCSL-1	Medium

Description
Microsoft Windows operating systems provide a feature called Authenticode. Authenticode technology and its underlying code signing mechanisms serve to provide a mechanism to identify software publishers and ensure that software applications have not been tampered with. Authenticode technology relies on digital certificates and is based on Public Key Cryptography Standards (PKCS) #7 (encrypted key specification), PKCS #10 (certificate request formats), X.509 (certificate specification), and Secure Hash Algorithm (SHA) and MD5 hash algorithms. .Net application developers sign their application code with their public key and Authenticode technology performs certificate validation tasks prior to allowing the application to run. Certificate validation tests include certificate revocation checks to determine if the certificate has been revoked by the certificate authority. In order for Authenticode to test the certificate for revocation, the authoritative revocation server must be available. If the revocation server is not available, the certificate status is unknown and the software must be prevented from running until the certificate can be validated. By default, Windows will allow application software to run if the certificate revocation server is offline and not available. This creates an integrity risk of malware being introduced into the system.

Description

Microsoft Windows operating systems provide a feature called Authenticode. Authenticode technology and its underlying code signing mechanisms serve to provide a mechanism to identify software publishers and ensure that software applications have not been tampered with. Authenticode technology relies on digital certificates and is based on Public Key Cryptography Standards (PKCS) #7 (encrypted key specification), PKCS #10 (certificate request formats), X.509 (certificate specification), and Secure Hash Algorithm (SHA) and MD5 hash algorithms. .Net application developers sign their application code with their public key and Authenticode technology performs certificate validation tasks prior to allowing the application to run. Certificate validation tests include certificate revocation checks to determine if the certificate has been revoked by the certificate authority. In order for Authenticode to test the certificate for revocation, the authoritative revocation server must be available. If the revocation server is not available, the certificate status is unknown and the software must be prevented from running until the certificate can be validated. By default, Windows will allow application software to run if the certificate revocation server is offline and not available. This creates an integrity risk of malware being introduced into the system.

STIG	Date
Microsoft Dot Net Framework 4.0 STIG	2014-01-08

Details

Check Text ( C-40063r15_chk )
This check must be performed for each user on the system. In order to determine compliance, the hexadecimal values contained in each users "State" registry key must be converted to binary values. Use regedit to locate "HKEY_USER\[UNIQUE USER SID VALUE]\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing\State". Document the hexadecimal value of the user's "State" registry key. Each character in the hex string will be referred to as a "nibble". For example, a hex value of 1da00 has 5 binary "nibbles". For guidance purposes, the nibble positions are numbered 1 through 5 starting from the right and moving to the left. Open the Windows calculator. Select "View", then "Programmer". Select "Hex" and then "Dword". Enter the 5 nibble hex value obtained from the user's registry key. Select "Bin". The hex value will automatically convert to a binary value. Start the count from 1 (not 0) and count the positions of the bit values starting from the right and moving to the left. The total number of bit positions will vary from 18 to 20 depending upon the hex values input into the calculator. If bit positions 11, 12, 13, and 14 are not "0" values on a production system, this is a finding. If bit positions 11, 12, 13, and 14 are not "0" values on a development system and the IAO has not provided documented approval, this is a finding.

Check Text ( C-40063r15_chk )

This check must be performed for each user on the system. In order to determine compliance, the hexadecimal values contained in each users "State" registry key must be converted to binary values.

Use regedit to locate "HKEY_USER\[UNIQUE USER SID VALUE]\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing\State".

Document the hexadecimal value of the user's "State" registry key. Each character in the hex string will be referred to as a "nibble". For example, a hex value of 1da00 has 5 binary "nibbles". For guidance purposes, the nibble positions are numbered 1 through 5 starting from the right and moving to the left.

Open the Windows calculator.
Select "View", then "Programmer".
Select "Hex" and then "Dword".

Enter the 5 nibble hex value obtained from the user's registry key.

Select "Bin".
The hex value will automatically convert to a binary value.

Start the count from 1 (not 0) and count the positions of the bit values starting from the right and moving to the left. The total number of bit positions will vary from 18 to 20 depending upon the hex values input into the calculator.

If bit positions 11, 12, 13, and 14 are not "0" values on a production system, this is a finding.

If bit positions 11, 12, 13, and 14 are not "0" values on a development system and the IAO has not provided documented approval, this is a finding.

Fix Text (F-35216r8_fix)
Using regedit, change the hexadecimal value of the "HKEY_USER\[UNIQUE USER SID VALUE]\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing\State" registry key. For production systems, change the hexadecimal values for nibble positions 3 and 4 to "0". For development systems, change the hexadecimal values for nibble positions 3 and 4 to "0" or the IAO must provide documented approval. Example fix: Hex value: 1da00 Nibble position: 54321 To apply fix, example hex value "a" in nibble position "3" and hex value "d" in nibble position 4 would both be changed to hex value "0" resulting in a final hex value of 10000.

Fix Text (F-35216r8_fix)

Using regedit, change the hexadecimal value of the "HKEY_USER\[UNIQUE USER SID VALUE]\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing\State" registry key.

For production systems, change the hexadecimal values for nibble positions 3 and 4 to "0".

For development systems, change the hexadecimal values for nibble positions 3 and 4 to "0" or the IAO must provide documented approval.

Example fix:
Hex value: 1da00
Nibble position: 54321

To apply fix, example hex value "a" in nibble position "3" and hex value "d" in nibble position 4 would both be changed to hex value "0" resulting in a final hex value of 10000.