the NBC[.]com website is redirecting to malicious websites that contains exploitkit.
At this point it seems like most of the pages contains an iframe that is redirecting to the first stage of the RedKit exploit kit.
Some of the iframes :
We’ll add these iframe domains tonight but you should not wait
Update: more complete list of domains here –>> http://ddanchev.blogspot.com/2013/02/dissecting-nbcs-exploits-and-malware.html