A method for detecting at least one group of abnormal nodes among a plurality of nodes (N1,... N6) of a communication network, the nodes (N1,... N6) of the communication network being linked together by communication links, each node (N1,... N6) being configured to establish at least one connection (C1,... C6) with at least one other node (N1,... N6) of the communication network via the respective communication link, said detection method comprising a step of receiving data relating to each connection (C1,... C6) between the plurality of nodes (N1,... N6) during an observation period, each connection (C1,... C6) being characterised by identifiers of the nodes (N1,... N6) linked by said connection (C1,... C6) and by a duration of said connection (C1,... C6); characterised in that the detection method further comprises the following steps: - determining a set of node groups (G1,... G8), each node group (G1,... G8) being characterised by a group duration during which each node (N1,... N6) of the node group (G1,... G8) has a connection to every other node (N1,... N6) of the node group (G1,... G8) and by the nodes (N1,... N6), chosen from the plurality of nodes (N1,... N6), with at least one connection (C1,... C6) with every other node (N1,... N6) of the same node group (G1,... G8) for the entire duration of the group; - determining, for each node group (G1,... G8), at least one parameter characterising all the connections (C1,... C6) implemented within the node group (G1,... G8), - obtaining said group of abnormal nodes from said parameter using a calculation model obtained by machine learning, the calculation model comparing the parameter with at least one reference parameter, the parameter being chosen from the list consisting of: - the number of connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter for the duration of the connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter of a data rate of the connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter of a connection density, the connection density of a communication link between two nodes (N1,... N6) of the node group (G1,... G8) being a probability of connection via that communication link at a given time during the group period; and - a statistical parameter of a degree of connection associated with each node (N1,... N6) of the node group (G1,... G8), the degree of connection corresponding to the number of nodes (N1,... N6) linked, for the duration of the group, by a connection (C1,... C6) at node (N1,... N6) with said degree of connection. - determining a set of node groups (G1,... G8), each node group (G1,... G8) being characterised by a group duration during which each node (N1,... N6) of the node group (G1,... G8) has a connection to every other node (N1,... N6) of the node group (G1,... G8) and by the nodes (N1,... N6), chosen from the plurality of nodes (N1,... N6), with at least one connection (C1,... C6) with every other node (N1,... N6) of the same node group (G1,... G8) for the entire duration of the group; - determining, for each node group (G1,... G8), at least one parameter characterising all the connections (C1,... C6) implemented within the node group (G1,... G8), - obtaining said group of abnormal nodes from said parameter using a calculation model obtained by machine learning, the calculation model comparing the parameter with at least one reference parameter, the parameter being chosen from the list consisting of: - the number of connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter for the duration of the connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter of a data rate of the connections (C1,... C6) of the node group (G1,... G8); - a statistical parameter of a connection density, the connection density of a communication link between two nodes (N1,... N6) of the node group (G1,... G8) being a probability of connection via that communication link at a given time during the group period; and - a statistical parameter of a degree of connection associated with each node (N1,... N6) of the node group (G1,... G8), the degree of connection corresponding to the number of nodes (N1,... N6) linked, for the duration of the group, by a connection (C1,... C6) at node (N1,... N6) with said degree of connection.