Zero-click felony

If malware can do this as a byproduct of browser redirections, how long before someone develops a virus that deliberately downloads child porn to deep, sinister directories on your hard drive? _That_ would be nasty.

It wouldn't surprise me if some particularly antisocial worm writers have taken up the challenge of writing the most lifelike (i.e., indistinguishable from a human) child-porn downloading worm. The winner would simulate human browsing patterns and even half-heartedly delete most of the files (whilst leaving the data for forensic detection), and toss out clues in a way that resembles carelessness. The worm/virus would also behave in a way that the writer could identify it from news reports of arrests. That way, when some poor fucker goes to the wall for your worm, the author of the worm and all the fellow nihilists they've bragged to knows that they've won.