If it was ISIS, I guess the bomb/device was on board.
What kind of hardware would it take to attack a jet at 31000? And could ISIS operate it.
Most any SAM system since the end of the 50s. What have we given them, what has KSA given them, what have they seized in fighting and in Iraq? Operating isn't that difficult and the manufacturers provide manuals in any language you need, Arabic for s already on the shelf. It's certainly within their capability to operate these systems. Do not underestimate the military training available to ISIS.