EDIT: As explained in the longer version, the problem's been solved! Just leaving this up here for posterity.
There’s a post floating around on tumblr which has a link to “myiqtcst.tumblr.com”. Please don’t click it; it’s a blatant scam. Seriously, there’s like 30 odd thousand people who’ve posted it in the same words. And it’s a dodgy redirect.
Don’t click it!
(also, if you think you’re in danger, change your freaking password, damnit!).
(this (and therefore this (it’s the same thing))) explains how I came to this conclusion and goes into more detail, but it’s a bit long).
(cross posted from my tumblr)