By Timothy B. Lee

Security researchers have spotted a new strain of malware that targets Bitcoin, the peer-to-peer virtual currency that exploded onto the tech scene earlier this year. In a report issued last week, Symantec researchers described a Trojan that uses the user's computer to mine Bitcoins on behalf of the intruder. They estimate that, at current exchange rates, a fast computer could generate as much as $150 worth of Bitcoins per month.

This is not the first Bitcoin-related malware spotted in the wild. In June, security researchers discovered malware that acts as a virtual pickpocket, scanning an infected computer for Bitcoin wallets and sending their contents to the attacker. There have also been previous reports of Bitcoin-mining malware, but estimates had suggested that most botnet owners would make more money renting their machines out for other uses.

In contrast, the newest Bitcoin malware takes full advantage of the computing power on each compromised machine—including its GPU. The parallel computing capabilities of modern GPUs means that they can perform certain specialized computing tasks much more quickly than traditional CPUs. And Bitcoin mining, which involves computing trillions of hashes, happens to be one such task. Symantec estimates that GPUs can compute hashes up to 750 times as quickly as a typical CPU. This means that while CPU-based mining can be expected to generate less than a dollar per month in Bitcoin profits, Badminer can generate as much as $150 per month.

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