https://www.grc.com/x/ne.dll?bh0bkyd2
Click on the "Proceed" button then click on the "GRC's Instant UPnP Exposure Test" button.
A significant number of routers have a bug which allows hackers to take complete control from anywhere in the world.
Want to know more about the problem?
Transcript of Security Now! podcast detailing the problem
http://www.grc.com/sn/sn-389.pdf
Sophos naked security blog post:
http://nakedsecurity.sophos.com/2013/02/05/upnp-flaws-turn-millions-of-firewalls-into-doorstops/