A demand letter sent last year by CBS chief Les Moonves to controlling shareholder Shari Redstone is playing out in the boardroom battle for control of the media giant, best-selling author Ken Auletta told CNBC on Friday.

"You have two scorpions in a bottle here. And each of them have the ability to kill each other. But they don't want to," said Auletta. His upcoming book, "Frenemies: The Epic Disruption of the Ad Business (and Everything Else)," details the Moonves letter to Redstone regarding her plan to merge CBS with its sibling company Viacom.

In a "Squawk Box" interview, Auletta said Moonves made nine demands in the 2016 letter to Redstone.

"Basically, it was we want to control the board. We want to appoint the board, independent directors," Auletta said. "Only Moonves could be relieved of his job by the independent directors, which he appointed. And Shari Redstone, though basically she had 80 percent voting control, would not have control. Exactly what played out here."

At issue: Redstone wants to CBS to merge with Viacom, with Moonves to lead the combined company and with Viacom CEO Bob Bakish as his No. 2. Moonves doesn't want Bakish looking over his shoulder.

On Thursday, the CBS board approved a special dividend that would cut the Redstone family's voting power to about 20 percent from 80 percent. However, the move cannot take effect unless it can overcome Redstone legal challenges.

National Amusements, the privately held movie theater company owned by 94-year-old Sumner Redstone and his daughter, Shari, holds a majority of the voting shares in CBS and Viacom. The two media companies had been under the same umbrella from 2000 to 2006 before they were split into separate publicly traded companies.