The company, in a statement, confirmed that hackers broke into their system and stole an unknown quantity of data, reported Entertainment Weekly.
"HBO recently experienced a cyber incident, which resulted in the compromise of proprietary information. We immediately began investigating the incident and are working with law enforcement and outside cybersecurity firms.
"Data protection is a top priority at HBO, and we take seriously our responsibility to protect the data we hold," the network confirmed in a statement.
So far, a written material which is believed to have been from "Game of Thrones" season seven's fourth episode and an upcoming episode of "Ballers" and "Room 104 " have apparently been put online.
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HBO chairman and CEO Richard Plepler sent an email to the company's employees alerting them of the breach.
"As most of you have probably heard by now, there has been a cyber incident directed at the company which has resulted in some stolen proprietary information, including some of our programming.
HBO had also faced the cyber breach during "Game Of Thrones" season five premier, when the first four episodes of the show were leaked online.