Integrity Protection For Embedded Systems

In their book, Embedded Systems Security, David and Michael Kleidermacher point out some all-to-real scenarios about the consequences of malicious threats to embedded systems.

Consider that for every PC in the world, there are hundreds of embedded systems, interconnected over various communication channels, like WiFi, Bluetooth and RFID. And nothing has become more computerized faster than the modern automobile. Computers, in the form of self-contained embedded systems, have been integrated into virtually every aspect of a car's operation and diagnostics, including throttle control, transmission, brakes speedometer, climate and lighting controls, external lights and entertainment systems.

The authors gave one example of an industrial company that sells bearings that use a magnetic field to suspend a shaft. A Digital Signal Processor performs 15,000 calculations per second to keep operations running smoothly. The bearing controllers have Ethernet connections.  With a coordinated attack on the bearings, plant operations could be brought to a halt.

The authors also discuss the security issues brought on by non-malware bugs. As embedded systems become increasingly ingrained in our lives, any bug that compromises the reliability of a system can become a mission-critical security threat. For example, what would happen if automated jail control doors failed to close? A task that errantly consumes too many resources (like memory) or CPU cycles can prevent other activities from running: the traffic light fails to turn red, the railroad signal remains open, or the ATM’s bill counter fails to stop spewing money. 

The Department of Homeland security notes that our country’s reliance on cyber systems to run everything from power plants to pipelines and hospitals to highways has increased dramatically, and our infrastructure is more physically and digitally interconnected than ever. Yet for all the advantages interconnectivity offers, critical infrastructure is also increasingly vulnerable to attack from an array of cyber threats.

Most embedded systems developers have little training in security and are largely unaware of both the threats and the techniques and technologies needed to make their products secure. In order to develop effective methods aimed at preventing attacks, the potential threat scenarios need to be understood. Some of the possible attacks to embedded systems are listed here below:

• Attackers develop a "fake device," a device that looks just like the original, but whose functions have been altered for nefarious purposes, that could be installed, for example, as a replacement part during equipment service.
• Attackers develop their own software and run it by replacing the memory card in the embedded system.
• Attackers extract the memory card out of the embedded system, manipulate the software and plug the card back into the system.
• Attackers modify the software on the embedded system by controlling the communication interfaces from the outside.
• Attackers monitor an embedded system, while in use by the application, in order to analyze it and to develop avenues of attack.

Finally, the authors make one more important point. They say that one of the most important tenets of computer security is that it is difficult, unwise, and often financially and/or technically infeasible to retrofit security capability to a system that was not originally designed for it. Therefore, they conclude, the only hope for improving security across the world of embedded systems is to educate the developers, who must learn to think about security issues as much as they already think about functionality, memory footprint, and debugging.

And that's where Wibu-Systems comes in. For 25 years, we have delivered the tools needed by software developers to protect their software against piracy, IP theft, and manipulation. We continue to incorporate state-of-the-art security technologies into our software protection tools for embedded systems and PC software as well as cloud services and mobile apps.

The term "Integrity Protection" encompasses security measures, namely protection of system resources, programs and data against unauthorized manipulation, or at least identification and display of such modifications. The challenge consists in guaranteeing data integrity, and, if not possible, bringing the system to a safe mode and stopping the execution of any function. The best integrity protection solutions are based on cryptography and associated security mechanisms, such as digital signatures and message authentication. This 12-page white paper will describe these advanced encryption techniques.