Manbang allows users to watch documentaries about North Korean leadership.
Several South Korean MPs said at a session that North Korean Defense Minister Hyon Yong-chol was executed in late April after falling asleep.
An official close to the ongoing investigation says that some aspects of the hack were beyond North Korea's abilities.
The embattled film became the No. 1 online movie in Sony's history.
The film opened in more than 300 movie theaters across the U.S. on Christmas Day, drawing crowds of people who said they were championing freedom of expression.
The U.S. officially says the tools and infrastructure used in the attack were similar to previous activity from North Korea.
The attack was an example of 'destructive activity with malicious intent that was initiated by a sophisticated actor,' a White House spokesperson said.