4. Turning you into a bot client
Another common use of your infected computer is as a client in a larger botnet attack. In this scenario, your computer's CPU cycles and network capacity are hijacked in an effort to send service-denying content or malware to specific targets. Small DDoS botnets involve a few thousand compromised clients; larger ones range in the hundreds of thousands.
Botnets are often rented to criminals, who compare prices and features the way you might browse a favorite online store. It's all fairly out in the open -- more than most people would believe. Botnets can be harnessed to temporarily take down a website, spread malware or spam, or act as a cog in a more elaborate scheme. The only positive about bot infection is that you're not the target of the attack.
The malign mystery of malware
Of course there could be other motives behind your computer getting hacked -- such as hacktivists commandeering your system -- or simply hacking your system for fun or practice. It's quaint to think hackers once did it for glory rather than money.
Unfortunately, once you're infected, it's almost impossible to determine the intent of the malware on your hard disk. Even if your antimalware program says you're infected with adware or a spam bot, you can't be assured that's the full extent of the damage -- or if the malware isn't some worst-case variant. The only safe action to take is to treat all malware like crimeware, wipe out your entire system, and rebuild. There's too much serious criminal intent these days to do anything else.
This story, "The 4 most likely reasons you were hacked," was originally published at InfoWorld.com. Keep up on the latest developments in network security and read more of Roger Grimes' Security Adviser blog at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.