Joan Harwood, treasurer of Dartmouth Fire District No. 3 in Massachusetts, handles an annual budget of about $1 million. While doing some routine online banking for the firehouse in 2010, she discovered that $375,000 was missing from the account.
It turned out that her computer had been infected with a malicious computer program, Zeus Trojan, that enabled hackers to access the account and steal the money. Zeus spies on keyboards and captures keystrokes to swipe usernames and passwords.
Harwood was far from Zeus Trojan's only victim. Using the malware, a cybercrime ring operating out of Russia made off with more than $70 million from online bank accounts.
Cybercrime—which ranges from bank account hacking to phishing (in which fraudulent emails are sent with the aim of obtaining data or cash from the recipient)—is vast.
(Read more: Nine people's shocking cybercrimes)
According to the Internet Crime Complaint Center, consumers lost more than $525 million to cybercrimes last year—an 8.3 percent rise from 2011.
A study by McAfee and the Center for Strategic and International Studies estimates that the cost of cybercrime may exceed $100 billion a year.
While hackers hone their craft of manipulating computer users, Michael Kaiser, the executive director of the National Cyber Security Alliance, provides seven ways consumers can protect themselves.