Set-top box Hacking: freeing the 'Freebox'

The French ISP 'Free' was the first to introduce a set-top box in France in 2002, named the Freebox. Four years later, the fifth version of the Freebox was released and distributed to customers. It comprises two devices: a router, and a PVR called the Freebox HD, both running Linux. The Freebox HD had innovative features at the time, such as live television control and HD capabilities. Such a device has a lot of potential for running homebrew, so I decided to hack it. I present how I got arbitrary code execution on the Freebox HD and then root privileges, using a chain of two 0-day exploits, one of which is in the Linux kernel. I then analyze the device, run homebrew software, and explain the structure of the ISP's private network that I uncovered while exploring the device.