Every electronic device you use, from a smart thermostat to an industrial robot, runs on firmware. This layer of code sits between the hardware and the software, quietly making the device work as intended. Because it is invisible to most users, firmware often becomes an overlooked part of product design. Yet attackers know it is a weak spot.
When firmware is not secure, the risks are serious:
- Devices can be reverse engineered, allowing competitors or criminals to copy intellectual property
- Hackers can inject malicious code, turning ordinary devices into attack vectors
- Exploits can lead to downtime, safety hazards, or regulatory non-compliance
This article explores how firmware security works, the most common threats, and the best practices to protect devices against reverse engineering and exploits.
What firmware security really means
To understand firmware security, we first need to define firmware itself. Firmware is a specific type of software permanently stored in non-volatile memory inside a device. Unlike applications, which you can easily install or remove, firmware is deeply tied to the hardware. It initializes components, manages low-level operations, and ensures that the device performs its core functions.
Because firmware sits at such a fundamental level, it is both powerful and vulnerable. When compromised, attackers can gain access not only to the device but also to the systems and networks it connects to.
Key reasons why firmware requires special attention include:
- Limited visibility, since firmware is rarely monitored in real time, which makes attacks harder to detect
- Complex update cycles, as updates are riskier and less frequent than application patches, leaving vulnerabilities unaddressed for long periods
- Direct hardware access, since firmware communicates with chips, sensors, and processors, meaning that weaknesses at this level can compromise the entire device
- A critical role in trust, because features such as secure boot, encryption, and authentication depend on firmware integrity
In short, firmware security is about ensuring that the code running at the hardware level is authentic, untampered, and resistant to exploitation. It requires a combination of design practices, update management, and defensive techniques tailored to the unique role firmware plays.
Common firmware exploits and threats
Now that we understand why firmware is such a critical layer in electronics, the next question is how exactly attackers exploit it. The list is long, and each method carries serious risks. By recognizing these attack vectors early, engineering teams can design defenses that stop them before they cause damage.
Source: MDPI
Reverse engineering
Reverse engineering happens when someone extracts and studies firmware code to understand how a device works. From there, attackers can:
- Clone intellectual property by recreating the design in competing products
- Find vulnerabilities faster than the original engineering team
- Modify functionality to bypass restrictions or unlock hidden features
This is common in consumer electronics and industrial equipment, where protecting intellectual property is as important as protecting security.
Firmware tampering
Tampering occurs when attackers alter the firmware, either before it is installed or during updates.
Modified firmware may:
- Collect sensitive data without detection
- Disable security features
- Create backdoors for future exploitation
Because firmware updates are less frequent than software patches, tampered firmware can remain active for months or even years.
Exploit injection
Here, attackers inject malicious code into the firmware, often by exploiting a vulnerability in the update process.
Source: MDPI
Once injected, the code can:
- Turn the device into part of a botnet
- Allow remote access and control
- Spread attacks to connected networks
Exploit injection is especially dangerous for IoT devices, where large numbers of unsecured units can be hijacked at scale.
Side-channel attacks
Not all attacks target the firmware code directly. Some exploit physical characteristics of the device, such as power consumption, electromagnetic emissions, or execution timing. 
Source:Science Direct
With enough data, attackers can:
- Extract cryptographic keys
- Infer sensitive operations
- Bypass encryption safeguards
These attacks are sophisticated but increasingly relevant in industries where hardware devices process sensitive data.
Supply chain attacks
Finally, not every attack comes from outside. Vulnerabilities can be introduced during the manufacturing process, particularly when third-party components or contractors are involved. In this case, attackers may embed malicious code before the device even reaches the customer.
Source: InfoSec
The variety of these threats shows why firmware security is not just about adding encryption or testing updates. It is about building resilience across the entire product lifecycle, from design to manufacturing and maintenance.
Protecting against reverse engineering
Reverse engineering is one of the most common and damaging attacks on firmware. When attackers extract code, they gain visibility into how a device works, which opens the door to cloning, vulnerability hunting, or direct manipulation. The good news is that proven techniques exist to make reverse engineering much harder, more expensive, and far less attractive.
Code obfuscation and binary hardening
Making firmware difficult to read or analyze slows down attackers dramatically. While obfuscation is not a complete solution, it raises the cost of reverse engineering.
Combined with binary hardening, it can:
- Break common disassembly tools
- Hide sensitive routines
- Delay exploitation long enough to make attacks impractical
Secure bootloaders and digital signatures
Secure boot ensures that only authenticated firmware runs on a device.
Source: Timesys
Using cryptographic signatures means that:
- Every boot process verifies firmware authenticity
- Altered or malicious firmware fails to load
- Devices gain a root of trust that cannot be bypassed easily
This method is widely used in industries where uptime and safety are non-negotiable.
Encryption of firmware images
Encrypting firmware binaries both at rest and during transmission makes it harder for attackers to extract useful code.
Source: Interrupt
Even if they capture the image, without decryption keys it remains unreadable.
- AES-based encryption is commonly used for firmware images
- Keys should be stored in secure elements or hardware security modules
- Combined with secure boot, encryption creates a strong defensive layer
Hardware security modules and secure elements
Storing secrets directly on microcontrollers is risky, since attackers can sometimes probe or dump memory.
Source: LearnCantrill
Using dedicated secure elements or hardware security modules instead provides:
- Safe key storage isolated from the main processor
- Built-in protection against tampering
- Hardware-level cryptographic operations
This adds resilience, especially for devices deployed in the field for many years.
Access control and debug interface lockdown
Many reverse engineering attempts start with open debug interfaces such as JTAG or UART.
Source: GitHub
Leaving these active in production devices is a major mistake. Manufacturers should:
- Disable or lock debug interfaces after development
- Require cryptographic authentication for any access
- Implement one-time programmable settings to prevent re-enabling
Protecting against reverse engineering is not about finding a single fix. It is about combining several layers of defense so that even if one method is bypassed, others remain in place. The goal is to make attacks expensive, unattractive, and ultimately unviable.
Secure firmware update practices
Firmware updates are a double-edged sword. On one side, they are essential for fixing vulnerabilities, improving performance, and adding new features. On the other side, they create an opening that attackers can exploit if the process is not properly secured. A single weak update mechanism can undo even the strongest design choices.
To make updates safe and reliable, engineering teams should adopt the following practices.
Encryption of update packages
Updates should never travel in plain text. By encrypting update files:
- Attackers cannot inspect the package contents
- Sensitive intellectual property stays protected
- Exploit injection during transit becomes far more difficult
AES-based encryption is a common choice, but the key factor is managing cryptographic keys securely and storing them in protected hardware modules.
Source: Embedded computing design
Authentication of updates
Encryption protects confidentiality, but authentication ensures integrity. Every update package should carry a digital signature that the device checks before installation. This guarantees that:
- Only firmware from trusted sources is accepted
- Malicious or tampered packages are rejected immediately
- Customers gain confidence in the reliability of updates
Source: Silicon Lbs.
Rollback protection
Attackers sometimes attempt downgrade attacks, where they reinstall older, vulnerable versions of firmware to exploit known flaws. Rollback protection prevents this by:
- Blocking updates that use outdated versions
- Maintaining version history and validation rules
- Ensuring that once security patches are in place, they cannot be undone
Source: MemFault
Secure over-the-air updates
Modern devices often rely on over-the-air updates, which are convenient but exposed to risk. A secure process requires:
- Strong encryption during transmission
- Signed updates verified before installation
- Integrity checks throughout the update process
- Failsafe recovery options in case of interruptions
Best practices for firmware security by design
Securing firmware cannot be solved with a patch once devices are already in the field. True resilience comes from building security into the design process itself. This ensures risks are addressed early, when fixes are practical and cost-effective.
Source: Wind R. Systems
Threat modeling during prototyping
Security should be treated as part of engineering, not as an afterthought. During prototyping, teams should:
- Identify potential attack surfaces such as debug ports or update mechanisms
- Consider both technical and physical threats, including supply chain risks
- Map out attacker goals, from intellectual property theft to service disruption
By doing this early, security becomes a design parameter just like power efficiency or thermal management.
Security testing in EVT and DVT cycles
Engineering validation test and design validation test are ideal stages for security checks. Integrating penetration testing and code reviews at these points helps to:
- Detect vulnerabilities before mass production
- Validate secure boot processes
- Verify that encryption and authentication features work under real conditions
This reduces the risk of shipping thousands of vulnerable units.
Source: TestFort
Penetration testing for firmware
Independent testing by specialists is one of the strongest ways to validate firmware security. These tests uncover:
- Weak cryptographic implementations
- Backdoors left open during development
- Side-channel vulnerabilities that may not be obvious in design
The cost of testing is minor compared to the impact of a large-scale exploit.
Source: All About circuits
Supply chain security
Firmware security is not only about the code you write. Vulnerabilities often enter through third-party components, libraries, or contractors. To reduce risks, teams should:
- Vet suppliers for security practices
- Avoid unverified open-source firmware libraries
- Require compliance with international standards for secure components
Supply chain attacks are rising quickly, making supplier management a core part of firmware security.
Continuous monitoring and update planning
Even after deployment, security requires an ongoing strategy. Planning for monitoring and updates from the start enables companies to:
- Respond quickly to new vulnerabilities
- Extend device lifespans safely
- Maintain compliance with evolving regulations
Building security into firmware design is no longer optional. With the growth of IoT, industrial automation, and connected consumer products, every weak device becomes a potential target. Applying these practices early protects products, reputation, and customer trust.
The business case for firmware security
For many companies, firmware security is still seen as a technical detail. In reality, it directly impacts costs, compliance, reputation, and competitiveness. Treating it as optional is no longer possible.
Prevention vs remediation
Fixing vulnerabilities during design is far cheaper than fixing them after deployment. A security flaw discovered in the field can:
- Trigger expensive recalls
- Require emergency updates that disrupt operations
- Cause long-term damage to customer trust
Investing in secure boot, encryption, and penetration testing upfront costs only a fraction of remediation.
Compliance and regulations
Governments and industry bodies are tightening rules for connected devices. Standards such as IEC 62443 for industrial automation, ISO/SAE 21434 for automotive cybersecurity, and NIST guidelines for IoT all require secure firmware practices. Non-compliance can mean penalties, lost certifications, or blocked market access.
Protecting intellectual property
In sectors like consumer electronics, industrial systems, and medical devices, firmware often contains the code that differentiates one product from another. If it is reverse engineered, years of research and investment can disappear overnight. Strong security ensures that intellectual property remains protected.
Conclusion
Firmware is no longer an invisible layer that companies can ignore. It has become one of the most attractive attack surfaces for hackers, one of the weakest points in many devices, and one of the greatest risks for businesses that rely on connected systems. When compromised, the impact goes far beyond a single device. It can spread across networks, expose sensitive data, and undermine customer trust.
Secure your hardware before vulnerabilities become liabilities. Detus engineers specialize in embedding robust firmware security practices from design to deployment. Protect your connected systems, safeguard sensitive data, and strengthen customer trust.