For the ad-hoc networks requiring strong privacy protection, privacy-preserving routing protocol is a crucial need. Unfortunately, none of the proposed or available protocols such as routing offers properties such as complete unlinkability and unobservability, the data and control packets being linkable and distinguishable. The USOR protocol has given a try to fulfil the requirement of unlinkability and unobservability resulting privacy-preserving routing against passive attacks. Despite the efforts to avoid the attacks, the wireless networks are still vulnerable to the worm-hole attacks.