This article proposes an immune-like approach to information security of modern complex systems. This approach is based on the use of immune-like methods to protect critical system nodes from a predetermined set of attacks, and to minimize the success of an attack on the system. The methodological approach is to systematize immunization tasks, tools, and modes to describe how modern systems can resist the proliferation of computer attacks. The main conclusions and recommendations are that using the immunization approach will not only improve the security of systems, but also define principles for building systems that are resistant to cyber attacks