Patent Application
20140195808
The present disclosure relates to secure message filtering to vehicle electronic control units, and more particularly, to secure message filtering to vehicle electronic control units with secure provisioning of message filtering rules.
As vehicle control systems become increasingly complex, interconnected and accessible through wireless communication, these systems also become increasingly vulnerable to security attacks. Embedded controllers (for engines, brakes, etc.) are typically designed to withstand hostile physical environments, but often little attention is paid to the security environment. It has generally been assumed that software running on each controller, connected to a common bus, can be trusted (i.e., not infected with malware), although that philosophy is beginning to change.
The presumption of security safety is no longer justified as recent studies have shown that vehicles with internet connectivity and/or wireless interfaces such as Bluetooth and WiFi may permit a platform in the vehicle to become infected. Such a malicious platform can then reprogram other controllers on the bus and/or send messages to these controllers which are capable of causing catastrophic harm to the vehicle and its occupants. One approach to this problem is to implement specific and unique security enhancements to each individual embedded controller, but this may require significant involvement on the part of all Original Equipment Manufacturers (OEMs) and may result in duplication of efforts or adoption of incompatible approaches.
Features and advantages of embodiments of the claimed subject matter will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals depict like parts, and in which:
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.
Generally, this disclosure provides methods and systems for implementing a rule-based message filter in the firmware of a bus controller for a bus, to which a vehicle's electronic control units are connected. The firmware may be protected from unauthorized manipulation and the message filter rules may be verified for authenticity and security. Additionally, methods are provided for generating secure message filter rules that may be authenticated prior to implementation.
Bus controller 132 may comprise firmware 134 implemented in a field programmable gate array (FPGA) or other suitable programmable logic circuitry. Bus controller firmware 134 may be programmed by a Joint Test Action Group (JTAG) programming unit 140 through a JTAG interface 142 or other suitable programming methods that are similarly inaccessible to the host processor 122 and any other processors or controllers associated with the vehicle. Limiting programmability access to the bus controller firmware 134 increases the security of that firmware 134. Programming of the bus controller firmware 134 includes message filter logic and message filter rule verification logic. The message filter rule verification logic may include a trusted rule-signing key as will be explained in greater detail below.
Bus controller firmware 134 is responsible for receiving unfiltered messages 126 from the host processor 122, filtering those messages and sending the filtered messages 152 to the bus 150. Bus controller firmware 134 performs this filtering based on rules 130 obtained from the message filter rule database 128. The filtering rules may be used to prevent unauthorized and/or potentially malicious messages from being sent over the bus 150 to various vehicle electronic control units (ECUs) 154. The bus 150 may be a Controller Area Network (CAN) bus or other suitable bus. The vehicle ECUs (154) may be embedded controllers for the engine, brakes, transmission or other vehicle systems or sensors.
Most ECU messages are original equipment manufacturer (OEM) specific and proprietary, and therefore the OEM generally determines how message filter rules are constructed so that messages sent to the ECUs 154 will be safe and appropriate. An initial set of rules may be pre-loaded or provisioned in the message filter rule database 128 by the OEM, but it is useful for the rules to be updatable through the wireless connectivity of the host platform 120, so that the OEM can evolve the rules over time to enable new features or close newly-discovered security vulnerabilities. New or updated message filter rules 114 obtained in this manner, however, generally cannot be trusted due to security vulnerabilities inherent in the internet and wireless networks as well as the fact that software running in the host processor 122, which has full access to these message filter rules 114, may be compromised.
In order to verify the authenticity and security of new message filtering rules 114 provided to the host platform 120, a secure rule provisioning system is employed. A trusted rule authoring entity 102, such as the OEM, is provided with rule authoring tools that enable the entity 102 to generate a digital signature to be associated with a newly authored set of rules. The rule authoring entity 102 sends the new set of rules and the digital signature 104 to a rule certification service 106 which can verify the identity of the rule authoring entity 102 based on the digital signature. The rule certification service 106 then generates a digital manifest to be associated with the new rule set to indicate that the rule set is trusted and sends this manifest 110 back to the rule authoring entity 102. The rule authoring entity 102 sends this rule set and manifest 108 to a provisioning system 112 where it can be made available to host platform 120 by any suitable method of transmission. Host platform 120 stores the rule set and associated manifest 124 in the message filter rule database 128.
Bus controller firmware 134 can verify the authenticity and security of message filter rules 130 obtained from the database 128, based on the manifest associated with the rule set, in combination with a trusted rule-signing key that is provided to the firmware 134 as part of the firmware 134 secure programming 142. The key may be an asymmetric key used in combination with the manifest to decrypt the rule set. If the bus controller firmware 134 cannot verify the authenticity of the message filter rules 130, it may ignore the new rules and continue to use an existing rule or it may cease to transmit messages to the vehicle ECUs 154 and signal an error condition.
By providing message filtering capability, executed on secure firmware using trusted message filtering rules, any compromise in the integrity of the host processor or the IVI system will not lead to a compromise in the security of the rest of the vehicle including safety critical ECU functions.
Although the automobile industry and OEMs may, over time, take steps to develop more secure ECUs, the rule based message filtering system described herein may be cooperatively employed with and take advantage of any additional platform security measures that are implemented in the future. In the meantime, the rule based message filtering system described herein may be employed to mitigate the risks posed by IVI platforms which have the greatest exposure to malware infection.
Embodiments of the methods described herein may be implemented in a system that includes one or more storage mediums having stored thereon, individually or in combination, instructions that when executed by one or more processors perform the methods. Here, the processor may include, for example, a system CPU (e.g., core processor) and/or programmable circuitry. Thus, it is intended that operations according to the methods described herein may be distributed across a plurality of physical devices, such as processing structures at several different physical locations. Also, it is intended that the method operations may be performed individually or in a subcombination, as would be understood by one skilled in the art. Thus, not all of the operations of each of the flow charts need to be performed, and the present disclosure expressly intends that all subcombinations of such operations are enabled as would be understood by one of ordinary skill in the art.
The storage medium may include any type of tangible medium, for example, any type of disk including floppy disks, optical disks, compact disk read-only memories (CD-ROMs), compact disk rewritables (CD-RWs), digital versatile disks (DVDs) and magneto-optical disks, semiconductor devices such as read-only memories (ROMs), random access memories (RAMs) such as dynamic and static RAMs, erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), flash memories, magnetic or optical cards, or any type of media suitable for storing electronic instructions.
“Circuitry”, as used in any embodiment herein, may comprise, for example, singly or in any combination, hardwired circuitry, programmable circuitry, state machine circuitry, and/or firmware that stores instructions executed by programmable circuitry.
The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Accordingly, the claims are intended to cover all such equivalents. Various features, aspects, and embodiments have been described herein. The features, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations, and modifications.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US11/62929 | 12/1/2011 | WO | 00 | 3/18/2014 |
