Systems and methods for identifying suspicious controller area network messages

1. A computer-implemented method for identifying suspicious controller area network messages, at least a portion of the method being performed by a computing device comprising at least one processor, the method comprising:

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;

observing, in the messages, a set of corresponding patterns that comprises:

a first pair of corresponding patterns that comprises a first content pattern in the messages that corresponds to a first timing pattern of the messages; and

an additional pair of corresponding patterns that is different from the first pair of corresponding patterns and that comprises an additional content pattern in the messages that corresponds to an additional timing pattern of the messages;

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

determining that the message is suspicious based at least in part on the content pattern of the message and the timing pattern of the message not matching any pair of corresponding patterns in the set of corresponding patterns.

2. The computer-implemented method of claim 1 , further comprising performing a security action in response to determining that the message is suspicious.

3. The computer-implemented method of claim 2 , wherein performing the security action comprises blocking the message.

4. The computer-implemented method of claim 1 , wherein:

the first pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent at regular intervals; and

the additional pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent outside of the regular intervals.

5. The computer-implemented method of claim 1 , wherein:

the first pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent during an active state of the controller area network device; and

the additional pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent during an inactive state of the controller area network device.

6. The computer-implemented method of claim 1 , wherein detecting the message that comprises the controller area network identifier, wherein the content pattern of the message and the timing pattern of the message do not match any pair of corresponding patterns in the set of corresponding patterns comprises:

creating a set of rules by creating, for each pair of corresponding patterns in the set of corresponding patterns, a rule that identifies messages that comprise the pair of corresponding patterns; and

detecting that the message does not adhere to any rule within the set of rules.

7. The computer-implemented method of claim 1 , wherein the controller area network device monitors at least one sensor of a motor vehicle.

8. The computer-implemented method of claim 1 , wherein:

each message within the messages comprises a series of bits;

observing, in the messages, the set of corresponding patterns comprises creating a mask that masks out bits in the series of bits; and

detecting the message with the content pattern and the timing pattern that do not match any pair of corresponding patterns in the set of corresponding patterns comprises monitoring, for each message, only bits in the series of bits that are not the bits masked out by the mask.

9. A system for identifying suspicious controller area network messages, the system comprising:

a monitoring module, stored in memory, that monitors, 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;

an observation module, stored in memory, that observes, in the messages, a set of corresponding patterns that comprises:

a first pair of corresponding patterns that comprises a first content pattern in the messages that corresponds to a first timing pattern of the messages; and

an additional pair of corresponding patterns that is different from the first pair of corresponding patterns and that comprises an additional content pattern in the messages that corresponds to an additional timing pattern of the messages;

a detection module, stored in memory, that detects 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;

a determination module, stored in memory, that determines that the message is suspicious based at least in part on the content pattern of the message and the timing pattern of the message not matching any pair of corresponding patterns in the set of corresponding patterns; and

at least one physical processor configured to execute the monitoring module, the observation module, the detection module, and the determination module.

10. The system of claim 9 , further where the determination module performs a security action in response to determining that the message is suspicious.

11. The system of claim 10 , wherein the determination module performs the security action by blocking the message.

12. The system of claim 9 , wherein:

the first pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent at regular intervals; and

the additional pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent outside of the regular intervals.

13. The system of claim 9 , wherein:

the first pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent during an active state of the controller area network device; and

the additional pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent during an inactive state of the controller area network device.

14. The system of claim 9 , wherein the detection module detects the message that comprises the controller area network identifier, wherein the content pattern of the message and the timing pattern of the message do not match any pair of corresponding patterns in the set of corresponding patterns, by:

creating a set of rules by creating, for each pair of corresponding patterns in the set of corresponding patterns, a rule that identifies messages that comprise the pair of corresponding patterns; and

detecting that the message does not adhere to any rule within the set of rules.

15. The system of claim 9 , wherein the controller area network device monitors at least one sensor of a motor vehicle.

16. The system of claim 9 , wherein:

each message within the messages comprises a series of bits;

the observation module observes, in the messages, the set of corresponding patterns by creating a mask that masks out bits in the series of bits; and

the detection module detects the message with the content pattern and the timing pattern that do not match any pair of corresponding patterns in the set of corresponding patterns by monitoring, for each message, only bits in the series of bits that are not the bits masked out by the mask.

17. A non-transitory computer-readable medium comprising one or more computer-readable instructions that, when executed by at least one processor of a computing device, cause the computing device to:

monitor, 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;

observe, in the messages, a set of corresponding patterns that comprises:

a first pair of corresponding patterns that comprises a first content pattern in the messages that corresponds to a first timing pattern of the messages; and

an additional pair of corresponding patterns that is different from the first pair of corresponding patterns and that comprises an additional content pattern in the messages that corresponds to an additional timing pattern of the messages;

detect 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

determine that the message is suspicious based at least in part on the content pattern of the message and the timing pattern of the message not matching any pair of corresponding patterns in the set of corresponding patterns.

18. The non-transitory computer-readable medium of claim 17 , wherein the one or more computer-readable instructions cause the computing device to perform a security action in response to determining that the message is suspicious.

19. The non-transitory computer-readable medium of claim 18 , wherein the one or more computer-readable instructions cause the computing device to perform the security action by blocking the message.

20. The non-transitory computer-readable medium of claim 17 , wherein:

the first pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent at regular intervals; and

the additional pair of corresponding patterns comprises a pair of corresponding patterns that occur in messages sent outside of the regular intervals.