The ESEA gaming network has been exploiting its users' powerful graphics cards to mine Bitcoins without their knowledge. "Mining" is the way Bitcoin is created — it involves dedicating some or all of a CPU or GPUs power to solving hashes, which in turn generates the virtual currency. The mining began on April 13th and affected thousands of gamers, who unwittingly mined over $3,700 worth of the currency. ESEA, which describes itself as "the largest competitive video gaming community in North America," wasn't aware that the Bitcoin mining was taking place, and blames the behavior on a rogue employee out for personal gain.

The full story on how and why the Bitcoin-mining software made its way to users' computers isn't yet available, but ESEA had been exploring the idea of adding a Bitcoin mining option to its client. The idea was canned on April 12th, but the next day, the rogue employee secretly distributed the code without permission. The code, which was embeded in the ESEA client, used the gamers' powerful computers to mine the virtual currency without their knowledge. The company quickly stopped the behavior after it was exposed by a user on the gaming network's forums (a post that Reddit later picked up). ESEA is donating the bitcoins to the American Cancer Society, along with an equal donation from its own account.

Using nefarious means to mine Bitcoins is nothing new — a botnet named ZeroAccess reportedly generates $2.7 million per year doing just that — but the fact that this came from within a trusted company is worrying. As Bitcoin slowly makes its way into the public consciousness, it's likely that we'll see more and more people trying to make a quick buck by using botnets to mine the currency.