Embedded systems are becoming a necessary component of everyday life. They are present in devices ranging from home appliances to industrial equipment to medical devices and automobiles. However, with increased connectivity and complexity, these embedded systems are also facing new security challenges. In this article, we will discuss some of the key challenges in embedded system design security and how organizations are working to address them.
1.Lack of updates
One of the major challenges with embedded systems is the lack of ability to receive security updates over their lifetime. Unlike personal computers and smartphones, embedded systems have limited resources and often operate in remote environments without constant internet connectivity. Once deployed, it becomes difficult to patch any vulnerabilities discovered in their software. Without updates, vulnerabilities can persist and be exploited. System integrators are now focusing more on designing devices that can receive over-the-air updates to patch vulnerabilities even after deployment. Techniques like partition-based updates and delta patching help reduce update sizes and make them feasible for resource-constrained embedded devices.
2.Insecure communication interfaces
Most embedded devices connect to external networks or communicate wirelessly to transfer data. Traditional security practices like encryption and authentication are often not implemented on these communication interfaces due to limitations of memory, processing and energy constraints. Attackers can exploit these interfaces to launch remote code execution attacks, eavesdrop on communication or tamper with device functionality. Developers need to carefully assess communication requirements and implement lightweight cryptography suited for embedded systems to secure data transfer interfaces.
3.Lack of embedded system-specific security standards
While general security standards like Common Criteria exist, there are no widely accepted security standards that provide implementation guidance tailored for embedded systems. This results in ad-hoc and inconsistent security implementations across different product categories. Efforts are ongoing to develop standards like Embedded Device Working Group (EDWG) that define security requirements, APIs and best practices for various classes of embedded devices. Such standards will help establish a minimum security baseline and enable more secure development of embedded systems.
4.Complex supply chain
Embedded systems have a complex global supply chain comprising of different vendors supplying individual components like processors, memory, sensors etc. This introduces risks of malicious hardware, software or firmware being inserted at any stage. Techniques like trusted execution environments, remote attestation and blockchain-based provenance tracking are being explored by organizations to secure the supply chain and detect any unauthorized modifications. Standards like ISO/SAE 21434 will also help establish supply chain security processes.
5.Lack of security skills
Developing secure embedded systems requires expertise in areas like cryptography, secure coding practices, formal verification etc. which are very different from traditional embedded skills. However, there is a significant shortage of engineers proficient in embedded security. Training programs and security education need to evolve to develop these specialized skills. Standards can also help by defining minimum security competencies for different roles. Overall, security needs to be integrated into regular embedded development processes.
6.Secure boot process
Secure boot is a critical aspect of designing embedded system security that ensures only authentic and unmodified firmware is executed during device power-on. However, designing tamper-resistant secure boot flows for resource-constrained devices is challenging. Attacks can target the boot ROM, keys or firmware images. Techniques like measured boot that involve cryptographic hash-chaining of components help strengthen the process but require careful implementation to avoid vulnerabilities. Standardized secure boot architectures suitable for different classes of embedded devices need to be developed.
7.Isolation of security-critical software
Embedded devices commonly run both general application code and security-sensitive functions like encryption/decryption on the same CPU and memory. This lack of isolation means any vulnerabilities in non-secure code could potentially be exploited to compromise the security functions as well. For example, a buffer overflow bug in a network driver could be leveraged to alter cryptographic keys or inject malicious code. To address this issue, a technique known as Trusted Execution Environment (TEE) can be used.
A TEE sets up an isolated secure area in the device’s memory where the critical security software runs independently of the main applications. This TEE memory cannot be accessed by normal application code, thus providing isolation. The CPU also switches context when transitioning between the TEE and normal environment to run code with different privileges. However, implementing a full-fledged TEE comes with performance and resource overheads for constrained embedded systems. Context switching between environments and duplicating memory pages for the TEE consume additional CPU cycles and memory. This overhead needs to be optimized to ensure minimal impact on overall system performance.
8.Device software maintenance over time
As embedded systems have a long operational life often exceeding traditional IT equipment, maintaining device software and responding to emerging threats over many years is a challenge. Techniques are required for long term software maintenance, threat modeling over the product lifecycle and establishing an end-of-life transition plan. Standardized software/firmware update mechanisms and long term vulnerability response policies need to be defined for critical infrastructure devices with lifetimes spanning decades.
Additionally, defining a clear end-of-life transition plan is important as eventually devices may become technically outdated. The plan should cover extending security support timelines and guidelines for replacement/retirement. For critical infrastructure that operate for decades, long term vulnerability response policies and assignment of maintenance responsibilities need to be defined. Regular security audits and penetration testing during the later phases of the product lifecycle can also help identify maintenance needs. With careful planning and the right processes, it is possible to support embedded devices with software/firmware maintenance, threat responses and security patches even beyond their normal operational periods. This is critical to ensure safety and resilience of systems with long service lifetimes.
Conclusion
Embedded system security of semiconductor design company presents unique challenges due to resource constraints and long operational lives of devices. While problems like lack of updates and complex supply chains plague all categories, future standards and platform features can help establish security baselines. Continuous skills development and treating security as a primary design requirement instead of an afterthought can help build more robust defenses. Overall, securing the vast embedded device ecosystem will require collaborative efforts between industry and policymakers.
