My password was a KeePass-generated password of 20 randomly generated alphanumerical characters (mixed case). Needless to say the password has been changed.
I've done a full antivirus scan of my system which found nothing. I've also used various tools such as TCPView, Wireshark, and Security Task Manager (as well as the Windows Task Manager) to see if any suspicious services or processes were running, and it seems my system is clean. I'm not sure what happened here, but it seems unlikely that the issue was on my end.
You are assuming your system is OK after *something* got compromised? Any password is useless against a keylogger (that includes a future Bitcoin cient offering wallet encryption).
Today crimeware kits are sold with a nice GUI for the thump your head variety criminal who barely knows left from right mouse button. A Bitcoin tailored kit will have some kind of exploit to get in, a module for uploading wallet.dat, keylogger/VNC etc. functionality if needed, a module for cleaning up after itself as if it had never existed and one for hiding itself from the usual suspects (all antiviruses, Spybot S&D, Wireshark, process explorer etc.) until such time that your wallet contains enough coin. Hell, the specialists already own a sizable number of machines and the crimeware might function as a search engine for interesting data on the botnet. They may even fix other vulnerabilities to keep the competition out and keep your system in shape to guarantee uptime (a dead zombie is worthless, heh).
The only way to be sure is to start completely fresh. Including BIOS flashes and viewing old backups as compromised too. And changing Bitcoin addresses, obviously.
I'm aware of how malware works, thank you. My bitcoins in my wallet have already been moved to a different machine, and seeing as this is not the machine I usually work on (I usually use my Windows machine for websites testing purposes only) the system being compromised is really not that big of an issue.
Regarding "hiding until there are enough coins" - you do realize the theft was from a Mt. Gox account and not from a wallet file? Did you even completely read my post?
What does KeePass do, is that one of those things that saves your passwords so you don't have to type them in? Sort of defeats the point, no?
I would say good thing you learned your lesson at 10 BTC instead of 100 BTC or 1000 BTC.
KeePass (and other password safes) are actually one of the few proper methods to manage randomly generated passwords. You can't just "grab someones passwords".
Mt. Gox also really needs to add some sort of secondary verification.
Yes, I was thinking about this too - maybe a confirmation e-mail for every account withdrawal, whether in BTC or USD?