I read via Richard Bejtlich's blog that Exploit Prevention Labs (XPL) announced a new monthly survey on the most prevalent exploits on the Internet. The survey reports that the Windows Metafile Vulnerability was the most commonly exploited vulnerability in May 2006. When a user visits sites under the control of black hats, this browser vulnerability is the most commonly exploited one. The data for the survey is collected from XPL customers who use SocketShield, an exploit prevention plugin. SocketShield, according to the site, works at the socket layer to block exploits. It seems to use some form of signature analysis to detect exploits. I couldn't find details of the survey's methodology, though. This is a good first step, and we'd love to know more: how many users form the dataset for the survey? How many websites is this data based on? It will be interesting to see how XPL's data compares with the results of Microsoft's Strider Honey Monkey Project. That uses a farm of bots that scout the internet looking for sites that carry exploits.