Security is beefed up across the board.
The most famous attempted hijacking of a cargo aircraft, I think, is the attempt by a FedEx F/O who was flying as a non rev on a flight from MEM-SJC. He brought a claw hammer on board and bashed all three of the flight crew in the head. He almost succeeded. The crew would not submit though. They landed the plane, a DC-10, back in MEM. Sadly this idiot blamed racism, not his inferior skills and bad attitude, on his troubles. He is now serving a life term in prison.
There is a book on this, I just can't find it to give the title just now.
The day you stop learning is the day you should die.