Management of our work from homes to aero planes is greatly aided by the Internet of Things. IoT has gradually incorporated several ground-breaking technologies, like Wireless Sensor Networks (WSN) and Mobile Adhoc Networks (MANETs), because its standards are significantly different from what the Internet can now offer. The network is required to use the Routing Protocol for Low Power and Lossy Network (RPL) as its Internet of Things (IoT) routing protocol. This is undesirably vulnerable to several interior assaults. To combat this, a variety of strategies have been employed, including cryptography, intrusion detection systems (IDS), etc. These algorithms not immediately applicable to the Internet of Things nodes because of their less power, lossy nature, and substantial computational cost. This study proposes a method for detecting malicious Sybil nodes in an IoT network using RPL and the THC-RPL. The examined and state-of-the-art techniques are compared to the proposed technique, and it is discovered that it outperforms them. It recognizes more threats while keeping the ratio of packet loss between 15 and 25%. The nodes continue to use 60 to 80 mj of energy on average per day. Node energy conservation increases by about 40% when network lifetime is improved by 50% overall. There are 10% fewer message exchanges and 0% storage expenses with the THC-RPL.