OS and IE version detection

I’ve looked around but haven’t came across something that helps me. In
my Ruby script, I want to acquire the Windows version and Internet
Explorer version of the individual running the script. Here’s the catch,
HTTP_USER_AGENT returns nil in the script, possibly because we run
through proxy, so I don’t think I can use that in any way.

Any other way to acquire those details other than using user_agent?