There's no security issue it's exploiting, and quicktime isn't involved. Infact, there IS no codec. What happens is:
- You go to the site. It pops up a window, saying that the porn you're trying to get without paying for needs a codec for quicktime.
- You then download an application that pretends to be a codec - it isn't, it's a trojan horse that gets something nasty onto your mac.
- Now, you've downloaded it, so you decide to install the application. You even trust it so much that you give it your admin password so it has full access to the system, and it installs.
Congratulations, you've now replaced the bit of software that connects your mac up with websites, and now when you go to ebay or your online bank, instead you go to a site that LOOKS normal, but is actually owned by some russian bloke who would very much like to borrow some money from your account.
Basically, there are no security breaches here at all, no holes in osx, quicktime or whatever else being exploited (not to say there are no holes - there are!). All that's being exploited is stupidity and trust.
