Serry Winkler was startled by a knock on her Denver apartment door last year. Three uniformed police officers with a warrant - for her computer.
Unbeknownst to Winkler, she had become both an unwitting accomplice and a victim to a crime, CBS News science and technology correspondent Daniel Sieberg reports.
"Your house has been broken into and you didn't even know it," Winkler said.
A hacker, based in Russia, used the Internet to infiltrate Winkler's computer and steal a credit card to make fraudulent purchases in her name.
"You're going on with your day, and you're just simply doing what you normally do, and then all of a sudden you find out somebody has committed a crime in your name," she said.
Winkler was part of a scam called a robot network, or "botnet." Here's how it works: a criminal finds your computer and plants a program that gives them total control. The criminal then uses your machine to find another one and so on … up to hundreds of thousands. It eventually forms a super-computer army.
"As commerce moves to the Internet, the thieves move to the Internet," said Shawn Henry, the deputy director of the FBI's cyber division.
Henry says these botnets can wreak havoc on the Internet, overwhelming commercial Web sites and sending most of the world's spam e-mail. That's all while quietly infiltrating millions of home computers.
"You might not see anything, but typically you'll see your computer acting a little slowly or unusually, because the bot - your computer as a robot - the resources of that computer, are actually being used by somebody else," he explained.
Once they control your computer, it's like they can see your desktop. An attacker can watch you log on to your banking or credit card site, read your password and then drain your accounts - all without you ever knowing.
By the time you realize your money is missing, it's too late. You're already a victim.
"Only by ensuring that you've got an active firewall in place, your anti-virus is up to date and you are familiar with what's occurring on the computer, only by taking those types of securing measures are you best able to protect yourself," Henry said.
Taking these precautions, and even just turning your computer off at night, are the best defense against having a low life turn your computer into an accomplice in a high-tech crime.
"Nobody gives any thought to it, and I didn't - until it happened to me," Winkler said.