From Blizz forums
We've seen people try fancy stuff to steal your accounts. They're not limited to the following:
1. Hijacking an ad banner to exploit a Flash vulnerability.
2. Hijacking an ad banner to exploit a PDF vulnerability.
3. Hijacking the Launcher's page. Since it's basically a web browser, it displayed what they wanted. It's generally a fake site where you fill in all sorts of account and personal info that we don't ask for.
4. Making a fake Launcher with the said fake page.
5. Fake addon installer packages.
6. Scams saying your account is under investigation and would be banned if you don't do something.
7. Scams saying that you won a free prize and to visit a site to claim it.
8. Scams that you're selected for an alpha or beta build, or even something like the World of Warcraft movie and to visit a site to get it. It usually has a payload waiting for you or has you log onto the site.
There's a lot more. We see people having their accounts compromised and locked out mostly due to the above. Having extra knowledge to prevent bad things from happening is something desirable.
On a side note adobe has had security issues. For those that don't know adobe publishes flash and .pdf format stuff, this includes video's you can find on youtube and other sites, and also...the curse updater program. Update your adobe software as soon as you can to eliminate (for now) the vulnerability.