Embedded Security for Developers

Embedded systems are everywhere, from medical devices to cars, making security crucial to protect against hackers. This guide covers:

Understanding Threats: Recognizing risks like malware, DoS attacks, and data theft.
Design Principles: Keeping designs simple and secure, using trusted components, and ensuring communication security.
Operational Security: Implementing secure boot, firmware updates, and runtime controls.
Compliance and Certification: Following industry standards and obtaining security certifications.

Whether you're a developer or just curious, understanding embedded security helps protect devices and data from emerging threats.

What Are Embedded Systems?

Embedded systems are like tiny, specialized computers that live inside other machines and gadgets. They’re not like regular computers that can do all sorts of things. Instead, they have one job or a few specific tasks. Here’s what makes them special:

Specialized hardware: They have specific parts like tiny controllers, sensors, and things that move or adjust based on what they need to do.
Real-time processing: They can quickly take in information and respond right away, which is super important for things like airbags in cars.
Software: They run on their own set of instructions, or firmware, that tells them how to do their job.
Connectivity: They can connect to the internet or other devices to share information or get updates.
Constrained resources: They have to do a lot with a little - meaning they don’t have much power or memory, but they still get the job done.

You find these systems in all sorts of things like heart monitors, cars, robots, and even your fridge. They work with the real world, doing important jobs quietly in the background.

Unique Attributes of Embedded Systems

Embedded systems are different from regular computers in a few key ways that make keeping them safe a bit tricky:

Resource constraints - They have limited power and memory, so any security measures can’t slow them down or take up too much space.
Real-time demands - They need to be super quick and can’t afford delays, especially when they’re doing critical tasks.
Long lifecycles - They’re made to last a long time, so keeping them secure over years is a challenge.
Interactions with physical processes - If something goes wrong, it could cause actual harm, so security is crucial.
Harsh deployment environments - They need to keep working even in tough conditions like extreme temperatures or dusty places.

Security for these devices needs to be smart and efficient, fitting into tight spaces, working super fast, and lasting as long as the devices do.

Embedded Security Landscape and Threat Models

Most Common Threats

Some of the big risks for embedded systems include:

Malware infections: Bad software like viruses and trojans can sneak into devices, steal info, or mess things up. They often come from shady emails, websites, or downloads.
Denial-of-service (DoS) attacks: Hackers can flood a device with too much traffic, making it slow or crash. These attacks are simple to do but can cause big problems.
Exploits of known vulnerabilities: If companies don't fix security holes fast, hackers can use these weaknesses. Keeping your device's software up to date is super important.
Data interception/theft: If data sent between devices isn't protected, hackers can listen in and steal information. Using encryption is like putting your data in a safe.
Reverse engineering: Sometimes, hackers take apart devices to find secrets like special codes or keys. Keeping these secrets safe is crucial.

Embedded-Specific Vulnerabilities

Embedded systems also have some specific weak spots:

Weak default credentials: Many devices come with easy-to-guess passwords. Changing these passwords is a must.
Unsecured data storage: Important info stored on devices should be locked up with encryption to keep it safe if someone tries to break in.
Lack of encryption: Not protecting stored data or data that's sent out leaves it open to hackers. Using strong encryption is essential.
Vulnerable code: Issues in the device's software, like bugs or flaws, can let hackers in. It's important to keep an eye out for these problems.
Insecure interfaces: Some development tools left on devices can give hackers deep access. Turning these off can help keep the device safe.
Unpatched software: If there's no way to update the device, it can stay open to attack forever. Planning how to send updates is important.

By knowing about these risks, developers can build stronger security into their devices from the start. Staying alert and following good security practices are key to keeping ahead of hackers.

Secure Embedded System Design Principles

Guidelines for Secure Embedded Architecture

When making devices with embedded systems, it's super important to think about security from the start. Here's how to do it right:

Keep it simple: The less complicated your device is, the fewer chances there are for hackers to get in. Stick to what's necessary and cut out the rest.
Divide and protect: Break your system into separate parts so if one part gets attacked, the rest can still be safe. It's like having multiple doors with locks instead of just one.
Safe fails: Make sure if something goes wrong, your system shuts down in a way that doesn't let hackers in. Better to turn off than to be open to attacks.
Limit access: Only let each part of your system do its job and nothing more. This way, even if something gets compromised, the damage is limited.
Check who's talking: Always make sure that when one part of your system talks to another, it's really who they say they are. This stops imposters in their tracks.
Check everything: Make sure all the information your system takes in is exactly what it should be. This helps stop bad stuff from getting in through the back door.

Building With Secure Components

Picking the right parts for your device is super important for keeping it safe:

Choose hardware wisely: Stick to the essentials. Every extra piece is another chance for hackers.
Be careful with outside software: Using software made by someone else can be risky. If you go this route, pick it apart to make sure it's safe or stick with stuff that's well-known for being secure.
Pick a secure OS: Some operating systems are made to be more secure. Look for those, especially if they're meant for devices like yours.
Add special security chips: Think about using chips designed for security. They help with starting your device safely, proving it's really your device talking, and keeping data secret.
Use trusted platform modules: These are like vaults that help keep your device's most important secrets safe from tampering.

By following these steps and choosing your parts carefully, you can build a device that's tough for hackers to crack.

Embedded Communication Security

Making sure that the way embedded devices talk to the outside world and to each other is safe is super important. This stops people who shouldn't have access from getting in or messing with things.

Securing External Interfaces

External interfaces like USB, Ethernet, WiFi, and cellular connections let embedded systems talk to other networks and devices. It's key to make these connections secure to keep attackers out.

Turn off any connections you don't need. If you're not using them, they can still be a risk.
Use firewalls to only let trusted traffic through on these connections. Block everything else.
Make sure all data sent over these connections is encrypted, so no one can sneak a peek or change it.
Check that both ends of a connection are who they say they are, using things like certificates or special keys.
Keep an eye on the traffic for anything weird that might mean someone is trying to break in.

Securing Internal Communication Buses

Inside an embedded system, different parts talk to each other through internal channels. These need protection too:

Use encryption to keep all the internal chats secret.
Make sure messages are really from trusted parts, using authentication.
Keep the most important parts on separate channels to limit an attacker's reach.
Watch the internal traffic closely for signs of unauthorized access.

Protocol	Authentication	Encryption	Resilience
CANbus	✖	✖	Low
ZigBee	✔	✖	Moderate
Bluetooth LE	✔	✔	High
LoRaWAN	✔	✔	High

Keeping both the ways in and within embedded systems secure is a must to stop hacks. There are special methods and tools to help layer up the security.

Secure Boot and Firmware Update Processes

Secure Boot Overview

Secure boot is a way to make sure that when your device starts up, it's only using software that hasn't been messed with. Think of it like a bouncer checking IDs at the door.

Here's a simple breakdown:

The device starts with a special key or certificate that's built-in and can't be changed. This is used to check the software.
When the software is made, it gets a digital signature, kind of like a seal of approval from the manufacturer.
When you turn on the device, it checks the software's signature to make sure it matches the special key. If everything checks out, it starts up. If not, it doesn't run.

This way, only software that passes the check can run on your device.

Secure OTA Firmware Updates

OTA updates let you send software updates over the internet directly to devices. It's important to keep these updates safe:

All updates need a digital signature from the trusted manufacturer. This proves the update is legit.
The update process should be encrypted, keeping the data safe from prying eyes.
After downloading, the device checks the update's signature before installing it to make sure it's not tampered with.
Using a counter that can't be reversed helps stop anyone from putting old, less secure versions of the software on the device.

By following these steps, you can keep the software updates secure and trustworthy.

Embedded Runtime Security Controls

Behavioral Monitoring and Analysis

Even after embedded systems are up and running, they still face threats. It's like they need a constant watch to catch any bad behavior. Here's how you can keep an eye on them:

Anomaly detection: This is about knowing what's normal for your system and spotting when something odd happens. Think of it like noticing someone you don't recognize suddenly showing up at a regular meeting. Machines can learn what's normal and alert you when something's off.
Signature-based detection: This method uses known patterns of attacks and bad software behavior as a checklist. It's like having a list of known troublemakers and checking everyone against that list. But remember, the list needs to be kept current with new troublemakers.
Heuristic analysis: This approach looks at behavior that might seem suspicious, like someone trying to sneak around security. It's not about knowing exactly what they'll do but spotting when they're up to no good.

Using these methods together helps catch problems that might slip through the cracks. If something strange is spotted, it can either be stopped right away or someone can be alerted to check it out.

Policy Enforcement

It's important to make sure only the parts of your embedded system that need to talk to each other can. This helps keep things tight and secure.

Firewall rules act like bouncers, deciding who gets to send data where. This keeps the bad guys from using weak spots to break in.
Privilege management is like giving out keys to only certain parts of the building. If someone does get in, they can't get everywhere.
Authentication checks if everyone is who they say they are before letting them access certain parts. It's like verifying an ID before allowing entry.

A policy engine is like a security guard that checks every request against the rules to see if it should go through. This keeps the bad guys from getting too far inside your system.

Compliance Frameworks and Certification Programs

Industry Standards Overview

There are a bunch of rules and advice out there to help keep embedded systems safe:

ISA/IEC 62443: This is about keeping industrial systems, like those in factories, safe. It talks about things like how to manage updates and keep systems separated safely.
IoT Security Foundation Framework: This set of tips helps make sure Internet of Things devices, like smart thermostats, are secure. It covers how to start devices securely, encrypt data, and control who gets access.
Platform Security Architecture (PSA): Created by Arm, this framework helps make Internet of Things devices more secure. It talks about understanding threats, following security rules, and making sure there's a trusted core in devices.

These guidelines help companies make products that are harder for hackers to break into.

Regulations and Compliance

There are also laws that require products to be secure:

California SB-327: If you make or sell a connected device in California after January 1, 2020, it needs to have basic security features. This applies to all sorts of devices.
EU Cybersecurity Act: If you're selling certain tech products in the EU after June 28, 2021, they need to meet specific security requirements. This includes things like smart cards and security devices.
FDA Premarket Cybersecurity Guidance: For medical devices that connect to networks, the FDA has suggestions to keep them safe. This is aimed at the people who design, develop, and make these products.

Following these rules is important not just for avoiding trouble with the law, but also for showing customers you care about keeping their data safe.

Security Certification Programs

Getting a security checkup from a third party can also help show your product is safe:

UL 2900-1: This standard from Underwriters Laboratories (UL) looks at network-connected products. It checks things like encryption, who can get access, and how vulnerabilities are reported.
IECEE CB Scheme: A worldwide program that certifies the cybersecurity of electrical and electronic parts. It focuses on international standards like IEC 62443.
CSfC Components: This program from NIST checks cryptographic modules against FIPS 140-3 standards and approves them for use in national security systems.

These certifications help prove to customers that your product has passed a thorough security check.

Conclusion

Embedded systems are the smart parts inside lots of devices we use every day, like health monitors, cars, and even our fridges. As these devices get smarter and connect to the internet, it's super important to make sure they're safe from hackers right from the start.

In this guide, we've talked about:

Understanding threats: Embedded systems can face all sorts of dangers, including malware, attacks that make them crash, hackers exploiting weak spots, theft of data, and reverse engineering. They also have to deal with limited resources, needing to respond instantly, lasting a long time, dealing with the physical world, and working in tough conditions.
Designing safely: Using simple designs, breaking the system into parts, having backup plans, controlling access, checking identities, and making sure everything is as it should be can help keep things safe. Choosing the right parts, software, and security measures is also key.
Keeping communications safe: Protecting how these systems talk to the outside world and each other with encryption, firewalls, and careful checking is crucial. Different technologies like CANbus, ZigBee, Bluetooth LE, and LoRaWAN offer different levels of security.
Secure starting and updating: Making sure only trusted software runs on your device with secure boot and keeping everything up to date safely is important.
Watching over operations: Keeping an eye on unusual behavior, using known patterns of attacks, and setting rules to limit access can help catch problems. This includes using things like the ModSecurity Core Rule Set or the Firmware AnalysisToolkit for deeper checks.
Following rules and getting checked: Guidelines like ISA/IEC 62443, IoT Security Foundation, and PSA give good advice on cybersecurity. Laws in places like California and the EU, and for medical devices, tell you what security you need. Getting a thumbs up from independent checks like UL 2900-1 or the IECEE CB Scheme shows your product is safe.

By sticking to these tips, developers can make devices that are tough for hackers to mess with. As threats change, working together across teams will be more and more important to keep everything secure.

What is embedded software security?

Embedded security is about keeping the tiny computers inside devices safe from hackers. This means using special hardware and software to control who can access the device and protect its data. It involves things like making sure only allowed people can get in, scrambling data so it can't be read without permission, and checking for unusual activity.

What is embedded system security for C and C++ developers?

For developers using C and C++, it's important to write code that's safe from attacks. This includes checking inputs, managing memory safely, handling keys and passwords carefully, and controlling who can access what. Tools and guidelines, like those from the Platform Security Architecture (PSA), help developers build in security from the start.

What is the difference between embedded security and cybersecurity?

Embedded security is all about protecting the device itself, making sure its hardware and software are safe. Cybersecurity is broader, protecting the device and its connections with the outside world, like the internet or other devices. This can include things like firewalls and monitoring to keep the whole network safe.

How do you ensure security management is an embedded system?

To keep an embedded system secure, use multiple layers of protection. This could be secure hardware, making sure the device starts up safely, limiting what each part of the device can do, watching for suspicious activity, and keeping communications safe. Following standards like IEC 62443 and using tools to keep an eye on everything can help manage security.