An international hacking contest scheduled to begin this weekend could cause headaches for organizations worldwide and disrupt the Internet, according to a warning from Internet Security Systems Inc. (ISS). The contest, known as the Defacers Challenge, awards points to malicious hackers who successfully compromise an organization's Web server and deface its Web pages. ISS first became aware of the contest last week by monitoring Web sites and Internet Relay Chat channels frequented by malicious hackers who specialize in defacements, according to Peter Allor, manager of X-Force Threat Intelligence Services at Atlanta-based ISS. Rather than focusing on the volume of defacements, the Defacers Challenge is set up to reward the skill of malicious hackers who can compromise systems running less prominent operating systems, including Apple Computer Inc.'s Mac OS and Unix variants such as IBM's AIX and Hewlett-Packard Co.'s HP-UX. Contest organizers even set up a Web page (www.defacers-challenge.com) that outlines the rules of the game, including a point system for compromised machines -- one point for Windows, five for HP-UX and Macintosh -- and guidelines for what counts as a valid defacement. The target is to deface 6,000 Web sites. A prize of free Web site hosting is offered to the malicious hacker who can reach that goal first or accumulate the most Web sites in trying to do so, according to information posted on the site. The challenge is scheduled to begin Sunday and last for six hours, though information on the exact time hasn't been released, Allor said. ISS doesn't know which hacker or group of malicious hackers is responsible for organizing the challenge. Although the contest and Web page may be a joke, ISS noticed an increase in reconnaissance and probing scans of Web sites that may be connected to the contest, Allor said. Malicious hackers may be scouting out high-value systems, or even compromising them in advance so that they can quickly be defaced once the contest begins, he said. ISS recommends that organizations deactivate unneeded public-facing Web servers and turn off unnecessary services on Web servers that are needed, in addition to applying any necessary software patches to potentially vulnerable machines, Allor said. Recently disclosed software vulnerabilities that haven't yet been patched are attractive targets for hackers, he said. The contest was postponed to today. Sorry but this is a little late.