Accessing the Internet via an open Wi-Fi network is risky because you have no idea who is the hot spot provider or who is connected to it. At the airport it may seem more secure to use a terminal to check your e-mail or update your Facebook status; however, according to Symantec, these terminals might not be secure at all.

In a recent article on the company's Web site, Nick Johnston, senior software engineer of Symantec Hosted Services, wrote that at one Internet terminal at a large airport in England, he saw an unusual "Defense Center Installer" dialog box that turned out to be a fake antivirus software, also known as "scareware."

Scareware is a type of malware that claims a computer is infected with viruses and tries to coerce the user into buying the full version of the software to clean the fictitious infection. It's common for this type of malware to try to disable or uninstall legitimate antivirus software, causing Windows Security Center to warn that no antivirus software installed. As this type of software is not really a virus, it's hard for legitimate antivirus software to detect and remove it.

The fact that the Internet terminal has this type of malware indicates that it is not protected and might be infected with other hidden, more dangerous malware such as a keylogger. Unlike "scareware," which makes its presence known, there is no obvious indicator that a keylogger is active while it silently captures users' input. This means that usernames and passwords for airline accounts, bank accounts, Web mail, social media accounts, or any other private accounts accessed on the terminal can be stolen.

For this reason, you should exercise extreme caution whenever you are using publicly available Internet access terminals and avoid doing anything that requires you to sign on to personal or corporate accounts. The best practice is to only enter your private and important information, such as bank account, Social Security number, and so on, on computers and networks that you know. If you share computers with other people, remember to change your passwords regularly.

A few minutes of negligence might result in costly consequences that could take a long time to fix.