Abstract: The disclosed computer-implemented method for identifying suspicious controller area network messages may include (i) monitoring, for a predetermined period of time, messages sent by an electronic control unit that comprise a controller area network identifier for at least one controller area network device, (ii) observing, in the messages, a set of corresponding patterns that each comprise a content pattern and a timing pattern, (v) detecting a message that comprises the controller area network identifier, wherein a content pattern of the message and a timing pattern of the message do not match any pair of corresponding patterns in the set of corresponding patterns, and (vi) determining that the message is suspicious based at least in part on content pattern of the message and the timing pattern of the message not matching any pair of corresponding patterns in the set. Various other methods, systems, and computer-readable media are also disclosed.

Abstract: The disclosed computer-implemented method for detecting transactional message sequences that are obscured in multicast communications may include (i) collecting a sequence of messages that were distributed on a communication channel and that include an obscured cyclic sequence of request-response messages that are interleaved in the sequence of messages, (ii) constructing a sequence graph from the sequence of messages by (a) adding, for each unique message identifier in the sequence of messages, a node to represent the unique message identifier and (b) adding, for each unique sequence transition in the sequence of messages from an immediately-preceding message to an immediately-succeeding message, an edge to connect the nodes that represent the identifiers of the unique sequence transition's immediately-preceding and immediately-succeeding messages, (iii) traversing the sequence graph to discover the obscured cyclic sequence of request-response messages, and (iv) performing a security action.

Abstract: The disclosed computer-implemented method for identifying message payload bit fields in electronic communications may include (i) monitoring messages transmitted via a network, (ii) selecting a plurality of messages transmitted via the network, each of the plurality of messages comprising an identical message identifier corresponding to a specified message type having a payload, (iii) determining for each bit position in the payload of the specified message type, a quasi-entropy value based on a proportion of occurrences of a first bit value and a proportion of occurrences of a second bit value at each corresponding bit position in the plurality of messages, and (iv) identifying at least one of a near-random bit field, a periodic bit field, and a constant bit field within the specified message type based on the determined quasi-entropy values. Various other methods, systems, and computer-readable media are also disclosed.