The Korea Information Security Agency (KISA) Tuesday warned of a Trojan horse program that steals online game identifications and passwords by hacking into the Web sites of game companies.

In its monthly report, the Korean agency said it found almost 1,000 Web sites in korea and other countries that included the clandestine malicious code.

The Trojan horse program sneaked into major Korean Internet sites with the aim of swiping personal data such as game IDs and passwords. The institute detected the virus in more than 800 Korean Web sites in cooperation with Internet service operators and ordered the sites to delete them.

The KISA also cut the connection to more than 100 innational Internet sites, which embedded the malware.

The KISA said the Trojan horse program cannot be prevented via the firewall shield of network because it exploits the weakness of Web browsers.

Instead, the agency recommended online game players install the latest security patch of their Web browsers to be safe from the new headache.