Mobile ad-hoc network is widely used in today's world as MANET is having characteristics such as wireless connectivity, dynamically changing topology. In MANET mobile nodes also act as router and interchange the data packets. MANET is used where fixed infrastructure is unavailable or infeasible. Such applications are battlefield communications, crisis management, emergency response operations etc. For these kind of application security is major issue. In MANET as mobile nodes also routes packet and lack of centralized point they are vulnerable to various routing attacks. In this paper, the authors attempt to survey on routing attacks such as black hole, worm hole and gray hole, packet drop attack on various routing protocols like AODV and DSR with their countermeasures.