South Korean police have warned that some online game downloads may contain malware intended to be used by North Korea in cyberattacks.

The warning came after the National Police Agency said Tuesday it had arrested a South Korean businessman for illegally trading in North Korean-developed online gaming programs that were found to contain malware for collecting IP addresses and other data from gamers' personal computers.

The collected data, transmitted to servers overseas, can be used for cyber terrorism like the distributed denial of service, or DDOS, attacks that have previously crippled thousands of South Korean computers, the NPA said.

The DDOS attacks are usually executed by malware-planted personal computers that turn out to be "zombie computers" unknowingly making a huge number of requests to targeted websites or networks, overwhelming their data-processing capacity and finally paralyzing them.

Cyberattacks crippled a number of websites run by South Korean state agencies, bank and new-media organizations in March and June this year—in both cases, Seoul blamed North Korea, which was also suspected of launching similar attacks in 2009, 2011 and 2012.