According to WoW (World of WarCraft) Insider, the World of Raids message board reports an unknown ad banner on Wowhead, Thottbot, and Allakhazam has an embedded trojan. Visitors to the sites don't even need to click on the banner, apparently. Simply moving your mouse pointer over the banner will be enough to infect your computer. Wowhead says that all they know for sure is that it originates from "ad.yieldmanager.com", and will produce a redirect to "xpantivirus.com."
Read the full report for details.