TL;DR
Yes, you can build more trusted electronics devices today, but it requires careful planning and execution throughout the entire development lifecycle. This guide outlines key steps to improve security from design to deployment.
1. Secure Design Principles
- Threat Modelling: Before writing a single line of code or soldering anything, identify potential threats. What could go wrong? Who might attack your device and why? Consider physical attacks, software vulnerabilities, network breaches, and data theft.
- Minimise Attack Surface: Only include the features absolutely necessary for your device’s function. Remove unused ports, services, and code libraries. The less there is, the less there is to attack.
- Defence in Depth: Don’t rely on a single security measure. Implement multiple layers of protection so that if one fails, others are still in place.
- Secure Boot: Ensure your device only boots trusted software. This prevents attackers from loading malicious firmware.
2. Hardware Security
- Tamper Resistance/Detection: Consider physical security measures to prevent or detect tampering with the hardware. Options include epoxy coatings, mesh layers, and sensors that trigger alerts if the device is opened.
- Secure Storage: Protect sensitive data stored on the device (e.g., keys, certificates). Use encrypted storage and consider using a Trusted Execution Environment (TEE) or Secure Element (SE) for key management.
- Hardware Root of Trust: Implement a hardware-based root of trust to verify the integrity of the software stack during boot and runtime. This is often achieved with a cryptographic chip.
- Side-Channel Attack Mitigation: Be aware of side-channel attacks (e.g., power analysis, electromagnetic radiation) that can reveal sensitive information. Implement countermeasures such as noise generation or shielding.
3. Software Security
- Secure Coding Practices: Follow secure coding guidelines to prevent common vulnerabilities like buffer overflows, SQL injection, and cross-site scripting (XSS). Use static analysis tools to identify potential issues early on.
- Regular Updates: Implement a robust update mechanism to deliver security patches promptly. Ensure updates are digitally signed to prevent tampering.
- Input Validation: Always validate user input to prevent malicious data from being processed by your device.
- Memory Safety: Use memory-safe languages (e.g., Rust) or employ techniques like address space layout randomization (ASLR) and stack canaries to mitigate memory corruption vulnerabilities.
- Least Privilege: Run software with the minimum necessary privileges. This limits the damage an attacker can do if they compromise a component.
4. Network Security
- Secure Communication Protocols: Use secure communication protocols like TLS/SSL to encrypt network traffic. Avoid using insecure protocols like HTTP or Telnet.
- Firewall: Implement a firewall to control network access and block unwanted connections.
- Authentication & Authorisation: Implement strong authentication mechanisms (e.g., multi-factor authentication) and authorisation controls to restrict access to sensitive resources.
- Network Segmentation: Isolate different parts of your network to limit the impact of a security breach.
5. Testing & Verification
- Penetration Testing: Hire ethical hackers to test your device for vulnerabilities.
- Fuzzing: Use fuzzing tools to automatically generate random inputs and identify crashes or unexpected behaviour.
- Static Analysis: Regularly scan your code with static analysis tools to detect potential security flaws.
- Code Review: Have multiple developers review each other’s code for security issues.
6. Supply Chain Security
- Component Sourcing: Carefully vet your component suppliers to ensure they have adequate security practices in place. Counterfeit components are a major risk.
- Bill of Materials (BOM) Management: Maintain an accurate BOM and track the provenance of all components.
- Firmware Integrity Checks: Verify the integrity of firmware from third-party suppliers before using it in your device.