Edward Follis, who wrote "The Dark Art: My Undercover Life in Global Narcoterrorism," explained that ISIS is profiting off of a whole "portfolio" of illegal activities, including human trafficking and slavery, pirating information technology and now, drug trafficking.
Follis said he believes ISIS is in the "nascent stages" of producing and trafficking methamphetamine and ecstasy, since they've now taken over pharmaceutical plants.
He believes that ISIS can also use drug addiction to its advantage in recruiting other terrorists.
"Especially methamphetamine as it is one of the strongest stimulants. We say in the states, it steals souls," said Follis.
Several reports have placed ISIS' net worth at around $2 billion, since the terrorist army also controls oil fields and refineries and has been selling oil on the black market.
Watch his full analysis above.