Yes its "vulnerable" but c'mon. How many LEET hackers are looking to exploit old android handsets with a possibility of recovering BTC? Same goes for paper wallet sweeps. I swept a wallet like ten times, scanning the private keys with no issues. We are in an infancy of technology with an infinitesimal amount of attention of hackers. ICO's and exchanges are way bigger fish to fry than a dude with .3230 bitcoin in a wallet on his android... just sayin