Disclosed are systems and methods for countering a cyber-attack on computing devices by means of which users are interacting with services, which store personal data on the users. Data is collected about the services with which the users are interacting by means of the devices, as well as data about the devices themselves. The collected data is analyzed to detect when a cyber-attack on the devices is occurring as a result of a data breach of personal data on users from the online service. A cluster of the computing devices of different users of the online service experiencing the same cyber attack is identified. Attack vectors are identified based on the characteristics of the cyber attack experienced by the computing devices in the cluster. Actions are selected for countering the cyber-attack based on the identified attack vector and are sent to the devices of all users of the corresponding cluster.