From TorrentFreak [torrentfreak.com]:
Chrome and Firefox are actively blocking direct access to the popular torrent site KickassTorrents. According to Google's Safe Browsing diagnostics service the site contains "harmful programs," most likely triggered by malicious advertisements running on Kat.cr.
[...]Instead of a page filled with the latest torrents, visitors now see an ominous red warning banner when they visit Kat.cr.
[...]The warning messages are triggered by Google’s “Unwanted Software” scanner which flags websites that pose a potential danger to visitors. Chrome and Firefox both use the service to prevent users from running into malicious software.
Still works in Konqueror and Epiphany.