As the value of bitcoins skyrockets, security researchers have discovered yet another piece of malware that harnesses the processing power of compromised PCs to mint the digital currency.

BTCs, as individual bitcoin units are known, have recently traded as high as $130, about four times their value from February. In Bitcoin vernacular, BTCs are "mined" by computers that solve cryptographic proof-of-work problems. For each correct block of data submitted, contributors are collectively rewarded with 50 25 bitcoins. Legitimate participants, who typically receive a percentage of the reward based on the number of blocks processed, often use powerful systems with multiple graphics processors to streamline the process.

But scammers spreading malware on Skype are taking a decidedly more nefarious approach. Their malicious code hijacks a computer's resources to mine BTC, according to a blog post published Thursday by a researcher from Kaspersky Lab. While the bitcoin-miner.exe malware harnesses only the CPU resources, which are much slower than GPUs in BTC mining, the attackers have the benefit of infecting many computers and then chaining them together to mint the digital currency. Unlike legitimate miners, the criminals don't have to pay the purchase price of the hardware or pay for the electricity to run them.

Bitcoin-mining malware has been circulating for almost two years now. Some versions actually tap infected computers' GPUs and can even run on OS X Macs.

The malware spotted by Kaspersky is most likely just a copycat phenomenon, but there's reason to think it hasn't been a waste of time for the people who created it. The bit.ly URL that had been hosting the malware was receiving more than 2,000 clicks per hour just prior to the Kaspersky blog post going live. That's a fair amount of distributed computing power.

"As I said, the campaign is quite active," Kaspersky Lab Expert Dmitry Bestuzhev wrote. "If you see your machine is working hard, using all available CPU resources, you may be infected."

Post updated to clarify Bitcoin reward system described in second paragraph.