"A few days ago I noticed some weird artifacts covering the screenshots I captured using the WoW game client application. I sharpened the images and found a repeating pattern secretly embedded inside. I posted this information on the OwnedCore forum and after an amazing three-day cooperation marathon, we managed to prove that all our WoW screenshots, since at least 2008, contain a custom watermark. This watermark includes our user IDs, the time the screenshot was captured and the IP address of the server we were on at the time. It can be used to track down activities which are against Blizzard's Terms of Service, like hacking the game or running a private server. The users were never notified by the ToS that this watermarking was going on so, for four years now, we have all been publicly sharing our account and realm information for hackers to decode and exploit. You can find more information on how to access the watermark in the aforementioned forum post which is still quite active."