Sometimes, when I'm browsing a random site, suddenly a 0 byte PHP file will be downloaded out of nowhere and Firefox (3.5.2) will start opening it in multiple tabs really quickly, so that I have to press Ctrl + W (close tab) as fast as I can until all the rogue tabs are closed. This file is frequently named diggthis.php, and some time ago it was a name I can't remember but it was the name of a search engine.
Could this be malware on my computer? Maybe a XSS attempt in the page I'm browsing?
This is very much likely malware on your computer. Use nice little proggie malwarebytes antimalware. Then install NoScript plugin to Firefox and you'll be a happier person.
Really - NoScript helps prevent 90+% of malware by effectively disabling entry points. You will need to manually allow scripts on trusted sites, but this thing is worth a few clicks now and then. I mean, it is so effective against malware that I can't find a sane reason why not have it.
If you still has problem with other browsers except Firefox (you might see the malware behaviors like opening tabs in them either), just download and install Hitman Pro from a secure website like cnet, it detects malware and associated files in your registry (type regedit in your start and then control F to find the file).
