These words sometimes show up in Google search results, but what do they mean? Google software engineer Oliver Fisher, said the server that the site runs on probably has a hole, a security vulnerability, most likely from some out-of-date software. That vulnerability has been exploited and malicious code has been added to the Web site. It's most likely an invisible script or iframe that pulls content from another Web site that tries to attack any computer that views the page. If the attack succeeds, then viruses, spyware, key loggers, botnets, and other nasty stuff will get installed on your computer.
So, pay attention if you see the warning on a site in Google's search results. Google has automatic scanners that constantly look for these sorts of Web pages. Now that you understand what the label means in search results, find out what to do about it if you're a Webmaster and Google's scanners have found malware on your site.