The Vertical Handover (VHO) is one of the most vital features provided for the heterogeneous mobile networks. It allows Mobile Users (MUs) to keep ongoing sessions without disruption while they continuously move between different Radio Access Technologies (RATs) such as Wireless Fidelity (Wi-Fi), Global System for Mobile Communication (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE) and Fifth Generation (5G). In order to fulfill this goal, the VHO must comply to three main phases: starting of collecting the required information and then passing it for decision phase to obtain the best available RAT for performing VHO by execution phase eventually. However, the execution phase still encounters some security issues which are exploited by hackers in launching malicious attacks such as ransomware, fragmentation, header manipulation, smurf, host initialization, reconnaissance, eavesdropping, Denial of Service (DoS), spoofing, Man in the Middle (MITM) and falsification. This paper thoroughly studies the recent security issues for hundreds VHO approaches found in the literature and comes up with a secure procedure to enhance VHO security during execution phase. A numerical analysis results of the proposed procedure are effectively evaluated in terms of security and signaling cost. Compared with the recent related work found in literature, the analysis demonstrates that the security is successfully improved by 20% whereas signaling cost is maintained as in non-proposed procedure.