From Halopedia, the Halo wiki
Busted is a medal awarded in Halo 4 and Halo 5: Guardians multiplayer and Spartan Ops for killing an enemy that is in the process of hijacking or skyjacking a vehicle or aircraft. It is represented by a Skyjack medal with a red "X" on the eagle.
- In Spartans Ops, it is possible to earn the Busted medal when you are the one being hijacked. This is because in Spartan Ops kills scored by AI allies in vehicles are awarded to the driver. Therefore if the player is driving a Warthog or Wraith and an Elite attempts to hijack them, and is subsequently killed by the AI gunner, the kill will be awarded to the driver, who will receive a Busted for foiling the hijack.