  We present an effective Sybil attack against social location based services.
Our attack is based on creating a large number of reputed "bot drivers", and
controlling their reported locations using fake GPS reports. We show how this
attack can be used to influence social navigation systems by applying it to
Waze - a prominent social navigation application used by over 50 million
drivers. We show that our attack can fake traffic jams and dramatically
influence routing decisions. We present several techniques for preventing the
attack, and show that effective mitigation likely requires the use of
additional carrier information.
