OS: Windows Server 2012 R2
It appears to query the registry and use the following:
HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Version which returns a value of: 9.11.9600.19377
The Version value is prefixed with a 9 for backwards compatibility, but it does not indicate version 9 of IE.
Another string value is present in the key. svcVersion is 11.0.9600.19377. This should probably be used as the basis for the version detection.
We are using the source edition if that makes any difference.