The security firm said the Facebook account details are changing hands for around 89p each. Cyber criminals are then obtaining access to the accounts and using them to send spam that contains links to video or audio sites.
Unsuspecting web users who click on the links will be directed to websites hosting malicious files. They'll then be encouraged to download the files, which infect PCs with malware that will steal passwords such as those for online banking accounts.
Trend Micro also revealed that there has been a five-fold increase in internet scams aimed at stealing personal details since September.
Senior security advisor at Trend Micro, Rik Ferguson, said: "We give away a huge amount of personal information on social networking sites. Hordes of cyber criminals are drawn to them. Whether you're going online to use Facebook, for banking or Christmas shopping, you should be aware that hacking and identity theft tends to increase at certain times of the year".