Title: Microsoft Windows File Protection Code-Signing Verification Weakness
Severity: HIGH
Description:
Microsoft Windows ships with a component to verify digital signatures that have been applied to system files and third-party code called 'Windows File Protection' (WFP). It has been reported that files signed using code-signing certificates issued by any trusted root CAs will be trusted by WFP. This includes operating system files and device drivers. Consequently, any attacker in possession of a code signing certificate rooted at any trusted CA may create malicious code signed with the certificate that will be trusted.
There are several root CAs preconfigured in Microsoft Windows. Some of these CAs may have dubious security practices. For example, some may issue SSL certificates without valid Key Usage, Enhanced Key Usage Object Identifier and Basic Constraints fields. This could result in the ability to use a SSL certificate to sign code which would be trusted by WFP. Furthermore, 'www.freessl.com' allegedly may be used by attackers to obtain certificates anonymously that are rooted at the trusted CA "usertrust.com".
While these faults may lie with the individual authorities, trusting root CAs for all signed code is a weakness in the design of Windows File Protection.
Affected Products:
- Avaya DefinityOne Media Servers
- Avaya IP600 Media Servers
- Avaya S3400 Message Application Server
- Avaya S8100 Media Servers
- Microsoft Windows 2000 Advanced Server
- Microsoft Windows 2000 Advanced Server SP1
- Microsoft Windows 2000 Advanced Server SP2
- Microsoft Windows 2000 Advanced Server SP3
- Microsoft Windows 2000 Datacenter Server
- Microsoft Windows 2000 Datacenter Server SP1
- Microsoft Windows 2000 Datacenter Server SP2
- Microsoft Windows 2000 Datacenter Server SP3
- Microsoft Windows 2000 Professional
- Microsoft Windows 2000 Professional SP1
- Microsoft Windows 2000 Professional SP2
- Microsoft Windows 2000 Professional SP3
- Microsoft Windows 2000 Server
- Microsoft Windows 2000 Server Japanese Edition
- Microsoft Windows 2000 Server SP1
- Microsoft Windows 2000 Server SP2
- Microsoft Windows 2000 Server SP3
- Microsoft Windows XP 64-bit Edition
- Microsoft Windows XP 64-bit Edition SP1
- Microsoft Windows XP Home
- Microsoft Windows XP Home SP1
- Microsoft Windows XP Professional
- Microsoft Windows XP Professional SP1
References:
- Microsoft: Q310791 Description of the Software Restriction Policies in Windows XP
- Microsoft: Q324036 HOW TO: Use Software Restriction Policies in the Windows .NET Server
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