The rapid developments in wireless multimedia sensor networks (WMSNs) have increased the demand for an efficient method of safeguarding multimedia data from attackers. As data are transmitted over a wireless medium, the authentication process needs to be provided with some efficient detection and prevention methods. The Sybil attack is one of the most common and involves replicating the identity of an original node in the network and behaving like a true node in order to retrieve/destroy information using this fake identity. An efficient enhanced random password comparison technique is proposed to detect and prevent Sybil attacks. The results of simulations indicate that the proposed method detects this type of attack more efficiently than existing methods. In addition to early detection, our application increases the throughput and reduces the average delay with an enhanced true detection rate. The identification of this malicious activity in its initial phases increases the efficiency of the system in terms of the data transmission process.