Method of forestalling attacks in a network, by slowing down a communication in a network including at least one computer including malware aimed at establishing a communication with a control server. The method includes: reception of a request to transfer data originating from the computer, indicating that the IP address of the security server has been provided to the computer in response to a domain name resolution request including a domain name associated with the IP address of the control server, the domain name being included in a black list; waiting for a smaller duration than an expiry period for a transport protocol transporting packets of the communication, a session being maintained during this expiry period in the event of inactivity; and dispatching a packet including a byte generated pseudo-randomly so as to maintain the session active.