Users of Advanced Micro Devices Inc.'s microprocessors may want to think twice before looking for technical support on the company's Web site. Customer support discussion forums on the forums.amd.com site have been compromised and are being used in an attempt to infect visitors with malicious software, an AMD spokesman confirmed Monday.

The problem was first reported Monday in a blog posting by Mikko Hypponen, manager of antivirus research at F-Secure Corp. in Helsinki. As of Monday morning, AMD technicians were still working to resolve the problem, according to AMD spokesman Drew Prairie.

Because AMD had just learned of the problem, Prairie could give few details on how the site was compromised or when AMD expected to have the issue resolved.

According to F-Secure's Hypponen, attackers are exploiting a widely reported flaw in the way the Windows operating system renders images that use the WMF (Windows Metafile) graphics format. This flaw was patched on Jan. 5, so users who are running versions of Windows that have the latest patches installed are not at risk.

Because of the nature of the WMF vulnerability, however, hackers could install any type of software they wanted on unpatched systems.

How the attackers were able to compromise the AMD forums is unclear. Hypponen said that the AMD server could have been hacked, but that the problem could also be due to an intrusion at an AMD partner Web site or at an ISP.

These kind of WMF exploits have already been seen on a number of Web sites, but AMD is the most high-profile victim. Because users tend to trust content being served by known Web sites like AMD, the hack is particularly troublesome.