The missing Malaysian airliner is quite a mystery and most likely a tragedy; our thoughts and prayers are with the victims and their families.
It appears that two passengers on the plane were flying with stolen passports, but it's unclear to me how common this is. The Malaysian Home Minister thinks that the security screeners should have noticed something amiss:
Malaysian Home Minister Ahmad Zahid Hamidi said the unidentified passengers appeared to be Asians, and blasted the border officials who let them through while carrying passports from Austria and Italy.
"Can't these immigration officials think? Italian and Austrian [passport holders] but with Asian faces," Hamidi fumed.