Even though it has been calculated that the use of botnets for Bitcoin mining is still not quite as lucrative as renting them out for other purposes, targeting people who have them in their digital wallets is quite another matter.
Symantec researchers have spotted in the wild a Trojan dedicated to this specific purpose. Named Infostealer.Coinbit, it searches for the Bitcoin wallet.dat file on the infected computer and sends it to the criminal(s).
The estimated number of infected systems is currently very low, but that it no guarantee for keeping safe - especially as the source code for locating the wallet and uploading it to a remote server is currently being offered on underground forums.
It is only a matter of time until the code is incorporated in other information-stealing malware.
"If you use Bitcoins, you have the option to encrypt your wallet and we recommend that you choose a strong password for this in the event that an attacker is attempting to brute-force your wallet open," advise the researchers.