Vulnerability Note VU#3062

The ActiveX control "Cenroll" (clsid: 43F8F289-7A20-11D0-8F06-00C04FC295E1), which is ordinarily marked safe-for-scripting allows callers to create files and write to the registry with the permissions of the process running the control. The Cenroll control is contained in the xenroll.dll library.

Using the call Enroll.createFilePKCS10 an attacker can create a file with an arbitrary name containing the base-64-encoded contents of a PCKS#10 request which can then be submitted to a Certificate Authority for processing. Nothing restricts the name or size of the file that can be created.

An attacker can create files with arbitrary names. The contents of the file can be influenced by the intruder, but it is unclear if the influence can be leveraged in any useful way.

The latest versions of Windows address this problem by limiting the number of times the control can be called before issuing a "denial-of-service" error message. (See Q242366). This prevents attackers from using the control simply to create large numbers of files. To the best of our knowledge, there does not exist a general purpose fix to the problem.