The growing and the widespread existence of the Internet of Things (IoT) has made our lives easier and more convenient. However, it still needs to dominate challenges, such as efficiency, security, and high energy consumption, to enrich innovative IoT-based applications. Unicast communication is used for small-scale applications. Multicast is preferable in large-scale communication because it allows efficient transmission with fewer resources and is utilized in various IoT applications. Multicast traffic involves actuator control to handle critical applications. Securing multicast traffic is complex as it needs an efficient and flexible Group Key Establishment (GKE) protocol. Therefore, this paper presents a temper proof of a three-level security model that can maintain the efficiency and security of IoT and multicast communications. The first authentication is done at network linking, where a 256-bit keyless encryption technique has been employed. Machine learning-based chaotic map key generation authenticates the GKE as the second-level authentication. Finally, Message Digest Algorithm 5 (MD5) establishes the system key. 3S-IoT is smart to detect any tempering with the devices. It stores the signature footprints of the connected devices. The algorithm is equipped to report any attempt to change or temper a device. 3S-IoT can thwart attacks such as Distributed Denial of Service (DDoS), Man-in-the-Middle (MiTM), and phishing. The numerical analysis is done by evaluating energy consumed, bandwidth, and the time taken to check the robustness of the proposed model. The results show that 3S-IoT can efficiently deal with the attacks. The work's authenticity is validated by comparing the proposed work with existing benchmark algorithms.