Wild Goose
I realise that the Malaysians are never going to say, but I'm thinking recent talk of very low altitude/terrain mapping may be them trying to explain discrepancies in their primary radar data. Like - why they picked up an unidentified aircraft at some points but not others (land over Malay Peninsula).
There is a video of a 777 re-enacted flight in the New Straits Tines where there was no secret that the Malaysians were toying with terrain mapping to "recreate primary radar and satellite data". Reading between the lines it's obvious the aircraft got through their defences that night.