“Web browser toolbars generally are a pain. Many of them promise the earth, but in reality all they do is redirect searches, mine users’ data and slow down computers. One, however, has been discovered taking its users’ computer resources to mine Bitcoins for its developers. According to security company Malwarebytes, the Myfreeproxy toolbar is designed to let users easily toggle a proxy server, allowing them to anonymise web browsing or watch foreign internet streaming broadcasts such as Hulu or Netflix US. However, buried in plain sight in the end user licence agreement (EULA) is a clause giving the program permission to install a Bitcoin miner on the user’s machine.”
http://www.theinquirer.net/inquirer/news/2316375/toolbar-enslaves-pcs-for-bitcoin-mining