As the description already says you have to win a match on each of the 3 maps "Main Vault", "Smelting Room" and "Loading Bay" which are all related to the Goldfinger mission (just as a sidenote).
The achievement's title "Midas Touch" refers to a greek myth about a king named Midas who is in some way similar to Auric Goldfinger, because everything he touched became gold.
If you have problems to win matches you can get this by yourself using the same strategy as posted by TheLeafsNation for the "Hold the Line" achievement.
Just start a game of "Data Miner" mode in an empty lobby and press "Start". This way you just have to walk around the empty map to make sure you don't get kicked out. After around 7 minutes you should have won the game. If the wrong map shows up, simply exit the lobby and go in again. If someone joins or the lobby is not empty, it would be better to try this on a less crowded time (though the multiplayer doesn't seem to be too crowded). In case someone joins late you might be already enough in lead to still win the match.
EDIT As confirmed by
Yoda8myhead you can also get this by simply being on the winning team in team conflict mode.