The augmented use of ICTs in power systems, and the dependency of the electrical infrastructure on this type of technology has created a new form of vulnerability: ICTs are exposed to denominated ldquocyberattacksrdquo. Due to this interaction as well as the importance of the electrical power systems, it is appropriate to assess the risk of how the power system security would be affected if it was subjected to this type of assaults. This paper is an overview of the main aspects related with the security of a power system with regard to cyberattacks and its assessment. Some definitions are recalled and completed with the aim of understanding what a cybernetic attack actually is, who the initiators of such an attack are, and what the possible consequences are. After, in order to assess the risk of power systems with regard to the possible consequences of cyberattacks, the use of a Bayesian network is proposed. The aim of this approach is to model the possible causes of cyberattacks against power systems and the consequences of such acts.