In the era of information and communication technologies, computer networks can beused to carry out modern forms of warfare. In light of technological advances, cyberattacks arebecoming more sophisticated and control over IT infrastructure is being lost. States can use digitaltools or enlist hacker groups to launch cyberattacks against other states. Such destructive actionsdamage the defence capacity, security, stability, and economic sustainability of a country, and hinderthe activities of public and private organisations alike. The situation is further complicated due tothe lack of a common understanding of the definition of the term „cyberattack“ among internationalactors. Furthermore, the existing international legal framework does not regulate the issue ofcyberattacks. The Charter of the United Nations was adopted in the 20th century when the processof creating cyberspace could not have been foreseen. Therefore, this article aims to explore thelegal definition of a cyberattack based on the reinterpretation of existing international norms. It isimportant to examine the possibilities of the development and adoption of new norms in cyberspaceand clarify the responsible cyber behaviour of states.