Techspot is reporting that Blizzard secretly embeds World of Warcraft player information into screenshot graphics in an effort to track down illegal private servers. A Slashdot member notice strange artifacts in WOW screen shots that he was taking. According to Techunknowns, after a few days, a group from OwnedCore was able to decrypt the information embedded in the graphics. They found that private user data has been embedded in screenshot images for as long as 2008. They noted that the embedded watermark is only added on screenshots taken with a quality of 9 or less presumably because higher quality graphics would make the watermark too visible.
The screenshot watermark contains the player’s account ID, timestamp of when the image was taken, and the IP address of the realm in which the player was in at the time. The embedded information should be enough to allow Blizzard to compare game server logs with the embedded information in order to filter out illegal game players.