In 2013, an unusual post appeared on Mark Zuckerberg's Facebook page. It was from a user called Khalil Shreateh.
"Dear Mark Zuckerberg," Shreateh wrote, "Sorry for breaking your privacy, I had no other choice to make after all the reports I sent to Facebook."
Shreateh, a security researcher from Palestine, had discovered a critical bug in Facebook's software that allowed anyone to post directly on to any user's wall. After he was ignored by the company's security team, he took the direct approach to demonstrating the bug - hacking Mark Zuckerberg's own page. While the incident showed the difficulties of getting cyber reporting right, Facebook has since become something of a pioneer in the growing field of "bug bounty" programmes.