SECURITY MODULE FOR A CAN NODE

A security module (560) for a CAN node (502). The security module (560) comprising: a RXD input interface (562) for receiving data from a CAN bus (504), TXD output interface (568) for transmitting data to the CAN bus (504), and a RXD output interface (564) for providing data to a local controller (510). The security module (560) is configured to receive a CAN frame from the CAN bus (504). The CAN frame includes a CAN message. The security module (560) is also configured to compare an identifier of the received CAN frame with at least one identifier associated with the local controller (510); and upon detection of a match between the identifier of the received CAN frame and the at least one identifier associated with the local controller (510): pass the received CAN message to the local controller (510) via the RXD output interface (564); decouple the local controller (510) from the CAN bus (504); and invalidate the CAN message on the CAN bus (504) via the TXD output interface (568).