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In recent years, the proliferation of the Internet of Things (IoT) has transformed the world of industrial automation and home automation. In these fields, connected devices control machines, manage critical data, and regulate essential home functions. However, this enhanced connectivity also makes these systems more susceptible to increasingly sophisticated cyberattacks. Therefore, security is a key factor in the design of embedded devices for smart home and Industry 4.0 applications.
Building a robust security architecture requires finding a balance between high-level protective measures and limited hardware and software resources, which is no easy task, as ensuring a high level of security often necessitates implementing advanced encryption and control functions that may impact device performance and power consumption. We will analyze various aspects of designing secure embedded devices.
The Importance of Embedded System Security
In recent years, embedded systems have become a core element of digital transformation across various industries, such as smart homes and Industry 4.0, which are the main areas where automation and device interconnectivity reach a high level of complexity. However, this development also brings some security limitations, necessitating effective strategies to protect networks and data.
IoT devices typically operate in resource-constrained environments, whether in terms of computing power or power consumption. Microcontrollers (MCUs) used for industrial temperature sensors may have only a few KB of RAM, with processing capabilities even lower than smartphones from a decade ago. However, the security of these devices cannot be overlooked, as any vulnerabilities could lead to widespread damage, from the loss of confidential data to disruptions in industrial production. Targeted attacks on critical sensors could have catastrophic consequences, such as halting an entire production line or leaking sensitive data related to strategic business processes.
Due to the design allowing many embedded devices to run for extended periods without frequent updates, they are particularly vulnerable to security threats that accumulate over time. Once a vulnerability is discovered, hackers may exploit it, and manufacturers often cannot provide quick fixes. We also need to consider the firmware supply chain: if an attacker manages to inject malicious code during production or updates, the system could be compromised even before it goes into operation. Therefore, implementing verification and authentication mechanisms at every stage of the device lifecycle (from production to field operation) is crucial.
Security Threats in Embedded Systems
The increasing prevalence of smart sensors, IoT devices, and automated machines means a rise in potential vulnerabilities that attackers can exploit to gain unauthorized access or disrupt normal system operations. Without adequate protective measures, the consequences can be catastrophic, including but not limited to network intrusions and operational failures, which can lead to significant economic losses.
Embedded systems are typically integrated into household appliances, industrial sensors, and automated machines, operating in highly interconnected environments and facing increasingly complex threats. Their distributed nature and growing reliance on the IoT exacerbate the risk of cyberattacks. Vulnerabilities can arise from various factors, including outdated firmware, insecure communication protocols, or a lack of robust authentication mechanisms.
Protecting these devices is not only about defending against intrusions but also ensuring the integrity and availability of information. If these systems are attacked, they could become vehicles for broader attacks (such as ransomware), causing devastating consequences for the operation and security of enterprise and personal data.
Why Security is So Important in Smart Homes and Industrial Systems?
In the smart home sector, interconnected devices control critical aspects of daily life, such as energy management, home security, and temperature regulation. Systems with inadequate security may allow attackers to gain remote access, manipulate operational parameters, or even disable essential functions. Secure communication protocols and advanced encryption technologies are key to preventing unauthorized access and ensuring that data transmitted between devices is not intercepted or modified. Additionally, managing login credentials, segmenting home networks, and employing dedicated firewalls are important strategies for enhancing security. Educating end-users about security is equally important, as attacks such as phishing or social engineering often exploit human errors to access systems.
In the industrial sector, the importance of security is even more pronounced due to its impact on production and business continuity. Modern factories utilize embedded systems to monitor production processes, optimize resource utilization, and improve overall efficiency, while cyberattacks targeting these systems can have severe consequences, such as production halts or machine damage. Network segmentation, the use of intrusion detection systems, and continuous traffic monitoring have become fundamental measures to protect critical infrastructure. The increasing interconnectivity between information technology and operational technology also brings new risks: attacks on traditional IT systems can spread to industrial machinery, causing catastrophic failures. Therefore, companies must take a proactive approach and invest in cybersecurity solutions tailored for industrial environments.
Security is not a static state but a continuous process that requires ongoing monitoring and timely patching. By automating the distribution of patch management system updates, it can help ensure that devices remain protected against emerging threats. Therefore, developers must take security measures, such as analyzing vulnerabilities in code and using automated testing tools. Collaboration between hardware manufacturers, software developers, and network operators is crucial to ensuring the resilience and reliability of the ecosystem. At the same time, the implementation of security updates must consider business continuity, especially in industrial environments, to avoid unintended disruptions.
Secure Boot: The First Line of Defense
Secure boot is one of the most effective technologies for ensuring the security of embedded devices. Through this mechanism, the device verifies the digital signature of the code at startup, preventing unauthorized firmware from running. If the firmware is not signed by the original manufacturer, the system will block its execution. This is crucial for protecting devices from tampering and the installation of any malicious code. Secure boot is particularly effective against attacks aimed at replacing the original software with malicious versions. For example, in home routers and industrial PLCs, hackers may attempt to install modified firmware to gain remote access to the system or steal sensitive information. Processors such as STMicroelectronics’ STM32 and solutions based on Arm TrustZone have built-in secure boot verification features, allowing developers to deploy secure boot without additional hardware, ensuring that devices can securely boot and protect critical data from the moment they are operational.
Arm’s TrustZone is an advanced solution that maximizes the security of IoT devices while minimizing hardware costs and complexity. Since IoT devices often operate in vulnerable environments, implementing robust security measures is essential for protecting sensitive data, encryption keys, and critical system functions. Many embedded developers often lack deep experience in encryption or cybersecurity, and time and budget constraints make it difficult to implement advanced solutions from scratch.TrustZone is a hardware mechanism implemented in single-core MCUs that addresses this issue by integrating isolation mechanisms directly into the MCU hardware and dividing the execution environment into secure and non-secure memory, peripherals, and functions.
TrustZone technology divides the system into two distinct environments: a secure environment (for managing critical operations and sensitive data) and a non-secure environment (for running user applications). Each environment has its own memory protection unit to prevent unauthorized code from accessing sensitive data. Therefore, for IoT developers looking to protect devices and data assets, TrustZone is an important tool. Security solutions can be implemented in various ways, although TrustZone positions itself as a single-core solution that provides traditional software development models. The only difference is that developers need to think from the perspective of secure and non-secure components, data, and threads.
MCUs securely boot the system by executing basic operations in secure mode and then switch to the non-secure environment to run user applications. To ensure data security, non-secure code can only interact with secure code through specially designed gateways, thereby reducing the risk of network attacks. STMicroelectronics’ STM32L5 series is a specific example of an MCU that employs TrustZone technology, equipped with dedicated development tools and kits for its application. Additionally, processors such as Cortex-M23, Cortex-M33, and Cortex-M55 integrate TrustZone as an optional feature, making it suitable for various embedded devices.
Hardware-based isolation is considered one of the most effective strategies for securing IoT devices, as it reduces the attack surface and prevents malware from compromising system integrity. With TrustZone, developers can implement advanced security measures without significantly increasing design costs or requiring in-depth knowledge of cybersecurity.
Secure Over-the-Air (OTA) Updates: Ensuring Software Integrity
Once a secure system is implemented at startup, this security must be maintained over the long term through secure over-the-air (OTA) updates. These updates allow embedded devices to receive new firmware versions without physical reprogramming. However, without adequate protection, they can become one of the main vulnerabilities of the IoT. This is because unauthorized updates could turn secure devices into threats to the entire network they are connected to.
A common attack method is to intercept and tamper with firmware during transmission, thereby using malicious code to compromise devices. To prevent this threat, encryption and authentication technologies for update packages have been widely adopted.Mender and MCUboot are platforms that provide comprehensive secure update management solutions, ensuring that only legitimate code can execute by implementing encryption verification before installation, thereby protecting the system from external threats. A practical example is a smart thermostat that frequently receives updates to optimize performance and fix vulnerabilities. Attackers may replace the original firmware with modified firmware to steal user habits or disable the heating system. Secure OTA updates verify the source and integrity of the firmware before installation, preventing such attacks from occurring.OTA updates can protect devices and prevent them from causing a chain reaction to other connected devices on the same network.
Authentication and Access Control
Embedded systems must be able to verify the identity of individuals attempting to access their systems and reduce the likelihood of attacks based on stolen or weak credentials. Multi-factor authentication, digital certificates, and encryption keys can enhance the overall security of the system and reduce the risk of intrusions. In industrial environments, maintenance often requires remote access, so robust credential protection and secure connection management solutions should be implemented. Additionally, biometric or hardware token-based authentication systems can add an extra layer of protection, making unauthorized access more difficult.
Firmware Protection
Attacks targeting the firmware supply chain are particularly dangerous, as they can affect thousands of devices before the issue is discovered. To mitigate this risk, companies must implement strict firmware control measures, such as digitally signing code throughout the development and production cycle. Additionally, it must be ensured that only verified firmware can be installed on devices, and the deployment process must be secure. Using digital signatures and automated verification systems helps prevent the intrusion of malicious code, as it ensures that only trusted software can run on devices.
The attack suffered by SolarWinds is a specific example, where the company’s software was compromised during production and distributed to thousands of customers without detection. To avoid similar situations, embedded device manufacturers must take measures such as secure encryption key management and public key infrastructure to ensure that only verified code can execute while also reducing vulnerabilities during the firmware design phase by adopting secure development practices. Vulnerabilities in the underlying software can be exploited to install malware or alter device behavior, so regular updates and code integrity verification are necessary to prevent malicious attacks. Implementing secure boot technology and authenticated updates helps reduce the risk of intrusion. Overall, conducting rigorous reviews of vendors and supply chain partners can mitigate the risks posed by vulnerabilities introduced unintentionally or intentionally.
Artificial Intelligence Enhancing Security
Utilizing artificial intelligence technologies for threat detection presents opportunities to enhance the security of embedded systems. Advanced algorithms can analyze anomalous behavior, identify intrusion attempts, and proactively respond to potential attacks. In industrial environments, these systems can help prevent failures and reduce the risk of operational disruptions due to security incidents. The combination of artificial intelligence and machine learning systems can identify unprecedented attack patterns, thereby enhancing the resilience of infrastructure. Predictive analytics combined with automated responses enable real-time intervention to mitigate losses before they become irreparable.
Designing secure embedded systems for smart homes and Industry 4.0 is a complex challenge that requires a multi-layered defense strategy. Implementing secure boot, secure OTA updates, and firmware supply chain protection is fundamental to building devices capable of withstanding cyberattacks. However, it should be recognized that security is not a static goal but a continuous process that must be updated and improved as technology evolves.
Investing in robust solutions helps create a reliably secure environment, reducing the risk of cyber threats and ensuring a safer future for embedded systems. A comprehensive approach that combines advanced technology with human cognition is crucial for building resilient and reliable digital ecosystems. Only through the effective combination of hardware and software solutions can the robustness and security of IoT systems be ensured in the long term.
Author: Giordana Francesca Brescia
(Editor: Franklin)