PC Tools plans on Tuesday to upgrade its anti-spyware software with improved protection against keyloggers.

Keyloggers, or keystroke-logging utilities, are software or hardware that watch what users are typing, and transmit the logs of the keystrokes to a central location. Frequently, they're used by attackers to capture credit-card numbers and other personal information typed by users at banking and other e-commerce sites.

The anti-keylogging in Spyware Doctor 3.2 looks for patterns of behavior in keylogging software, including software that attempts to access the keyboard API, replace the keyboard driver, or attempts to hide its processes from system management tools.

It also looks to see whether keystroke-logging software has a GUI, on the theory that most software that doesn't have a user interface is probably spyware.

Looking for keyloggers by behavior rather than signatures improves the speed at which keyloggers can be detected, said company CEO Simon Clausen.

"If you have a keylogger on your system for an hour or two hours it's a major threat if you logged into an online banking site in that time. You can't have it sitting on your site for a week or a month waiting for signatures to get updated," he said.

Last week, Brazilian authorities nabbed a man charged with being part of a phishing gang that stole $37 million from online bank accounts. And British authorities reportedly stymied an attack using keystroke-logging software against the London offices of Sumitomo Mitsui. It would have been by far the largest bank heist in British history.

Spyware Doctor also adds realtime blocking of some spyware.

"We're taking the approach that it's far better to stop the infection from getting on the PC than to wait for it to get there to remove it," Clausen said.

Full realtime spyware blocking will be available in version 4 of the software, due by the end of June.

Spyware Doctor 3.2 also adds improved protection against spyware that attempts to re-install itself after it's been uninstalled by users, and against harmful cookies.

The software is priced at $29.95 per seat, with volume discounts available.