A malicious hacker managed to compromise a computer belonging to a US Air Force officer and steal files related to one of the United States’ deadliest airborne weapons.

Sensitive documentation related to the maintenance and operation of US MQ-9 Reaper military drones has recently become available to the highest bidder on a hacker forum on the gloomy web, warns Recorded Future, a company specializing in real-time threat intelligence.

According to the company’s research team called Insikt Group, a hacker managed to exploit a previously disclosed router vulnerability to infiltrate the computer of “a captain at 432d Aircraft Maintenance Squadron Reaper AMU OIC, stationed at the Creech AFB in Nevada” and steal a trove of documents, which included Reaper maintenance course books and the list of airmen assigned to Reaper AMU.

“While such course books are not classified materials on their own, in unfriendly hands, they could provide an adversary the ability to assess technical capabilities and weaknesses in one of the most technologically advanced aircrafts,” the team notes.

The hacker also offered another cache of documents for sale, such as manuals on “improvised explosive device defeat tactics, an M1 ABRAMS tank operation manual, a crewman training and survival manual, and tank platoon tactics.”

These documents were also non-classified  and were likely stolen from the Pentagon or some US Army official.