Free VPN service Hola is selling users’ bandwidth for profit to a third-party service called Luminati, which re-sells the connections. Luminati is one of the world’s largest VPN networks that lets users buy access to the Hola network for a fee, in case if users need a secure way to route commercial traffic without revealing their identity. This isn’t known until 8chan message board administrator Fredrick Brennan posted a message about the service, claiming users’ computers have been used within a botnet to attack and take down his website.
Source: https://thehackernews.com/2015/05/hola-widely-popular-free-vpn-service.html