The network is hacked yet again in the space of three weeks.
HBO's Facebook and Twitter accounts have been taken over by an organisation going by the name OurMine.
The group, which markets itself as a penetration testing organisation specialising in social media security, took over the main HBO accounts as well as others belonging to the network's shows, as reported by the BBC,
The posts read: "Hi, OurMine are here, we are just testing your security, HBO team please contact us to upgrade the security - ourmine .org -> Contact".
The posts were removed quickly afterwards.
OurMine is known for hacking well-known people's social media accounts, including those belonging to Mark Zuckerberg and Google CEO Sundar Pichai. On the group's website, it claims to be "an elite hacker group known for many hacks showing vulnerabilities in major systems". Despite this, it defines itself as White Hat, claiming it has no bad intentions and cares only "about the security and privacy of your accounts and network".
A spokesperson for HBO said: "The infringement on social media accounts was recognised and rectified quickly."
We've contacted OurMine for comment.