A340 is probably a bit big for drug running and limited in the airports it can use. I've heard of turbo props with additional tanks doing the South America to Africa leg via the closest two points though. My guess would be that the aircraft was bought for Iran Air or Mahan Air. Fuel consumption is no issue for Iran's airlines and no one else wants the A340. The range would be useful as sanctions prohibit refuelling in many countries. The ability to carry fuel for prolonged holding and the return leg would come in very handy.