Security researchers from Symantec have identified a new trojan that uses the graphic card resources of infected computers to mine Bitcoins on behalf of its authors.

Bitcoin is a peer-to-peer cash-like virtual currency that can be exchanged by users without the need of a central bank or payment processing service.

Because of its enhanced anonymity, Bitcoin has quickly been adopted by privacy advocates, hackers, fraudsters and cyber criminals alike.

Bitcoins currently trade for around $11 and are generated by mining, a form of encryption cracking that follows a self-regulating algorithm.

Bitcoin mining requires powerful hardware or a distributed network of computers working together in order to increase the chances of success.

Malware authors have figured out that botnets could be used for Bitcoin mining and designed trojans designed to do this.

One such piece of malware that was detected at the end of June incorporated BitCoin Miner, a legitimate Bitcoin mining application. Another more recent one, was designed to use Twitter as command and control server.

Security researchers from Symantec now warn that a new Bitcoin mining trojan is capable of using GPUs from infected computers in order to increase its efficiency.

But the trojan doesn't get straight to it. It performs a check to see if the graphic card is powerful enough before using it. If it's not, it scales back to regular CPU-based mining.

"To perform the mining functions, the Trojan contains both the RPC miner and Phoenix miner programs. The latter can take advantage of the extra power of the GPU for bitcoin mining," the Symantec security researchers explain.

To put things into perspective, an Intel i7 990 is capable of a rate of 33.3 Mhash/s, that's 33.3 million hashes tried per second. Meanwhile, an AMD Radeon HD 6990 graphic card is capable of a rate of 758.82 Mhash/s.