From the looks of things, OurMine compromised Facebook’s Khoros account and used that to post the unauthorised message to the social media giant’s Twitter account. Khoros is a platform used by big brands to manage their social media engagement and err.. clearly, in the case of Facebook’s Khoros account at the very least, it wasn’t properly secured.
Thankfully OurMine has a history of being more interested in mischief than malice. They could so easily have tweeted out a phishing link or directed Facebook fans towards a site harbouring malware.