How I Hacked Facebook and Found Someone's Backdoor Script
This is Reginaldo from the Facebook Security team. We're really glad Orange reported this to us. On this case, the software we were using is third party. As we don't have full control of it, we ran it isolated from the systems that host the data people share on Facebook. We do this precisely to have better security, as chromakode mentioned. After incident response, we determined that the activity Orange detected was in fact from another researcher who participates in our bounty program. Neither of them were able to compromise other parts of our infra-structure so, the way we see it, it's a double win: two competent researchers assessed the system, one of them reported what he found to us and got a good bounty, none of them were able to escalate access.