The soaring value of bitcoins has prompted an update in CryptoLocker, the malware that encrypts the contents of victims' entire hard drives until they pay a ransom.

As Ars reported in September, Cryptolocker gives victims 72 hours to pay a ransom if they ever want to see their data again. (The trojan was later updated to allow laggards to retrieve their data for a higher price.) When CryptoLocker first emerged, the malware demanded two bitcoins. Based on the value of a single bitcoin at that time, that was in the neighborhood of $200 to $400, depending on the exchange rate and the day. Over the past month, the value of a bitcoin has risen sharply, from $100 to $150 in September to prices in excess of $700 this week, according to charts such as this one

This spike hasn't been lost on the people behind CryptoLocker. According to researchers at F-Secure, a new version of the ransomware is demanding 0.5 bitcoin.

The CryptoLocker people may lack scruples, but they can't be accused of lacking business acumen. Like any savvy marketer, they seem to know that the price of their product shouldn't be beyond the value reasonable consumers (or, in CryptoLocker's case, victims) are willing to pay.