Abstract. Critical infrastructures are very important tools which are paramount to the development of any nation. Therefore, they must be protected and catered for in order to promote their longevity. Information and Communication Technology (ICT) critical infrastructures are significant amenities which the nations depend solely upon in order to run their day to day transactions. Similarly, some advanced systems like the computerized integrated systems are used to support many functions and to improve their efficiency. Examples include the power grid generation control system, the railway stations in transport, the health infrastructure etc. There are numerous vulnerabilities and attacks on the network which these infrastructures are inter connected to in order to make them function well and to serve the populace. These attacks compromise the Confidentiality, Integrity and Availability (CIA) of a computer with internet network. However, this paper aims at providing comprehensive security gaps in ICT critical infrastructure and their preventive measures by critically reviewing related works that have been done and suggest possible ways to improving the system so that the people can be served well with the resources, and similarly to prevent the attackers from hacking into the system when there is a system breakdown.