Hackers using the name "Mr Smith" have posted a fresh cache of stolen HBO files online and demanded HBO pay a ransom of several million dollars to prevent further such releases.
The data dump included what appear to be scripts from five Game of Thrones episodes, including one coming episode, and a month's worth of email from the account of Leslie Cohen, HBO's vice-president for film programming.
There were also internal documents, including a report of legal claims against the network and job offer letters to top executives.
In a video for HBO chief executive Richard Plepler, "Mr Smith" used white text on a black background to threaten further disclosures if HBO did not pay up.
To stop the leaks, the purported hackers demanded "our 6 month salary in bitcoin", which they implied was at least $A7.6 million.
HBO, which previously acknowledged the theft of "proprietary information", says it continues to investigate and is working with police and cybersecurity experts.
The network says it still does not believe its email system as a whole has been compromised.
This is the second data dump from the purported hackers.
Entertainment Weekly reported last week that hackers stole 1.5 terabytes of data and posted un-broadcast episodes of Ballers and Room 104, along with "a script or treatment" for this week's episode of Game of Thrones.
So far the HBO leaks have been limited, falling well short of the chaos inflicted on Sony in 2014.
In that attack, hackers unearthed thousands of embarrassing emails and released personal information of nearly 50,000 current and former Sony employees.
Those behind the HBO hack claim to have more data, including scripts, coming episodes of HBO shows and movies, and information damaging to HBO.