Microcontroller Firmware Extraction & PCB Clone
Professional MCU firmware extraction, IC reverse engineering, PCB duplication, schematic recovery and PCB manufacturing services for clients worldwide since 1998.
Professional MCU firmware extraction, IC reverse engineering, PCB duplication, schematic recovery and PCB manufacturing services for clients worldwide since 1998.
The Renesas RH850 family of automotive microcontrollers is among the most widely deployed chips in the automotive industry, powering engine control units, transmission controllers, body electronics, and advanced driver assistance systems in millions of vehicles worldwide. The RH850/F1L variant, in particular, is designed for chassis and safety applications, with a focus on real-time performance and functional safety. To protect the proprietary firmware and calibration data stored in these chips, Renesas implemented a robust debug authentication mechanism based on a 16-byte password known as IDCODE. When IDCODE protection is enabled, all debug and memory access operations are blocked until the correct 16-byte password is provided through the debug interface. However, in May 2024, security researchers Jerin Sunny and Shakir Zari published a detailed account of how voltage glitching can be used to bypass the IDCODE authentication on the RH850/F1L, enabling complete firmware extraction from automotive ECUs. This case study examines the voltage glitching attack on the RH850/F1L, the specific weaknesses in the IDCODE authentication mechanism, and the implications for automotive cybersecurity.
The RH850/F1L is a 32-bit automotive microcontroller based on Renesas's proprietary RH850 core architecture, operating at up to 80 MHz and featuring up to 1 MB of flash memory and 64 KB of RAM. The chip includes a comprehensive set of automotive peripherals including CAN interfaces, ADC converters, motor control timers, and safety features such as ECC memory, watchdog timers, and a built-in self-test (BIST) mechanism. The RH850 family is designed to meet the stringent requirements of ISO 26262 functional safety, with features supporting ASIL-B and ASIL-C safety levels. For security, the RH850/F1L implements the IDCODE authentication mechanism, which is the most commonly used protection level for RH850 MCUs in production vehicles. When IDCODE is enabled, the chip's debug interface (which supports both JTAG and Renesas's proprietary serial programming interface) requires the correct 16-byte password to be entered before any memory read, write, or erase operations are permitted. Without the correct password, the bootrom commands for accessing flash memory remain inaccessible, and the chip effectively appears as a black box to an external debugger. The IDCODE is stored in a dedicated region of the chip's option memory, which is itself protected from unauthorized modification. The 16-byte length of the password provides 128 bits of entropy, making brute-force attacks computationally infeasible. Renesas designed the IDCODE mechanism to provide strong protection against firmware extraction, assuming that physical access to the debug interface alone would not be sufficient to bypass it.
The voltage glitching attack on the RH850/F1L targets the moment when the chip verifies the IDCODE password provided by the debugger. During the authentication process, the chip reads the 16-byte password from the debug interface, compares it against the stored IDCODE value, and sets an internal flag indicating whether authentication was successful. If the flag indicates success, subsequent debug commands are allowed; if it indicates failure, access remains blocked. The voltage glitch is applied at the precise moment when the comparison result is being evaluated or when the authentication flag is being set, causing the CPU to incorrectly set the flag to "authenticated" even though the password was incorrect. The attack requires physical access to the ECU board and the ability to control the chip's power supply voltage. The researchers identified the VCL pin (the internal core voltage regulator output) as the most effective point for applying the glitch, as it directly powers the CPU subsystem and code flash while having minimal effect on the chip's peripherals and voltage monitoring circuits. The glitch is generated using a ChipWhisperer or similar fault injection platform, which produces a precisely timed voltage drop of a few nanoseconds duration. The researchers used a systematic approach to identify the optimal glitch parameters, sweeping the glitch offset (timing relative to the IDCODE command), the glitch width (duration of the voltage drop), and the glitch repeat (number of consecutive pulses) while monitoring the debug interface's response to determine when authentication had been successfully bypassed.
The RH850/F1L voltage glitching attack proceeds through several stages. First, the attacker gains physical access to the target ECU and identifies the RH850/F1L chip and its debug interface pins. The debug interface may be exposed through a connector on the ECU board, or the attacker may need to locate and solder wires to the appropriate test points on the PCB. The attacker then connects a fault injection platform (such as a ChipWhisperer Husky or a custom glitch generator based on the Raspberry Pi Pico) to the chip's VCL pin and ground, and connects a debug adapter to the chip's serial programming interface. The attack begins by sending an IDCODE authentication command with an incorrect (or empty) password through the debug interface. As the chip processes this command, the glitch generator applies a voltage drop to the VCL pin at a precisely timed moment, attempting to cause the CPU to skip or corrupt the instruction that sets the authentication failure flag. If the glitch is successful, the chip sets the authentication flag to "success" despite the incorrect password, and the debug interface becomes fully accessible. The attacker can then use standard RH850 programming commands to read the entire flash memory contents, extracting the complete firmware and calibration data. The researchers found that the attack has a success rate of approximately one in twenty attempts once the optimal glitch parameters are identified, and that the parameters are consistent across multiple ECUs of the same model, making the attack practical for real-world exploitation. The entire process, from initial setup to successful firmware extraction, typically takes several hours, with most of the time spent on identifying the correct glitch timing through parameter sweeping.
A key innovation in the RH850/F1L attack was the use of Simple Power Analysis (SPA) to precisely identify the timing of the IDCODE verification routine, enabling more accurate glitch triggering. The researchers measured the power consumption of the chip on the ISOVCL pin (the ISO internal regulator that powers the CPU subsystem and code flash) while the IDCODE authentication was being performed. They identified a distinctive approximately 4 microsecond pattern in the power trace that corresponded to the password verification routine, and used this pattern as a trigger for the glitch. This approach is significantly more reliable than using a fixed time delay from the command issuance, as the exact timing of the verification routine may vary due to interrupts, cache effects, or other system activity. The SPA trigger ensures that the glitch is applied at the correct moment relative to the actual password comparison, regardless of variations in the chip's execution timing. The researchers also found that the power trace pattern was consistent across multiple ECUs from different manufacturers, validating the approach for cross-device use. The use of SPA for triggering represents a significant advancement in fault injection techniques, combining side-channel analysis with fault injection to create a more powerful and reliable attack. This hybrid approach, sometimes called "glitching with side-channel triggering," is increasingly being used in attacks on complex microcontrollers where the exact timing of security-critical operations is difficult to determine through software means alone.
The RH850/F1L voltage glitching attack has significant implications for automotive cybersecurity, as it demonstrates that the IDCODE authentication mechanism, which is widely relied upon to protect automotive ECU firmware, can be bypassed with relatively modest equipment and expertise. With the ability to extract firmware from RH850-based ECUs, attackers can reverse engineer proprietary control algorithms, extract calibration data and encryption keys, and identify vulnerabilities that can be exploited to modify vehicle behavior. In the context of automotive security, modified ECU firmware can be used to disable emissions controls, increase engine performance beyond safe limits, bypass safety interlocks, or introduce malicious behavior that could compromise vehicle safety. The attack also enables ECU cloning and counterfeiting, as competitors or criminals can extract the firmware from a genuine ECU and replicate it in counterfeit units, undermining the intellectual property investments of automotive manufacturers. The RH850 family's widespread use in safety-critical automotive applications means that a vulnerability in its security mechanism has potentially severe consequences. The UNECE R155 regulation, which mandates cybersecurity management systems for vehicle manufacturers, explicitly requires that manufacturers assess and mitigate physical attack vectors including fault injection, and the RH850/F1L attack demonstrates that this requirement is well-founded. The attack also highlights the gap between the security capabilities of automotive microcontrollers and the evolving threat landscape, as chips that were designed with strong logical security can still be defeated through physical attacks that the designers did not adequately anticipate.
Renesas has acknowledged the voltage glitching vulnerability in the RH850 family and has recommended several mitigation strategies for automotive manufacturers. The company has noted that the attack requires physical access to the ECU and specialized fault injection equipment, and that the risk should be evaluated in the context of each vehicle's threat model. For new designs, Renesas has recommended using RH850 chips with enhanced security features, including the RH850/U2A and RH850/E2x families, which include additional physical security measures such as glitch detection circuits, voltage and temperature monitoring, and a hardware security module (HSM) for secure key storage and cryptographic operations. For existing RH850/F1L-based ECUs, several mitigation strategies can be applied. At the hardware level, adding additional decoupling capacitance to the VCL pin can reduce the amplitude of glitch pulses that reach the CPU core, making the attack more difficult. At the system level, ECU enclosures can be designed with tamper detection mechanisms that erase sensitive data or disable the chip when the enclosure is opened. At the software level, sensitive algorithms and calibration data can be encrypted, with decryption keys stored in a separate secure element or derived from a hardware unique key. Automotive manufacturers can also implement secure boot and firmware integrity checking at the application level, ensuring that even if an attacker extracts the firmware, modifying it will cause the device to fail integrity checks and enter a safe state. Finally, the automotive industry is increasingly moving toward centralized vehicle architectures with dedicated security gateways and over-the-air update capabilities, which can reduce the impact of individual ECU compromises by isolating critical functions and enabling rapid response to discovered vulnerabilities.
The RH850/F1L voltage glitching attack represents a significant milestone in the evolution of RH850 hacking, which has progressed from early DIY glitch attempts to sophisticated, well-documented attacks using commercial-grade equipment. The first public demonstrations of RH850 fault injection were relatively crude, using simple MOSFET-based glitch generators and trial-and-error parameter selection. The 2024 attack by Sunny and Zari represented a major advancement, incorporating SPA-based triggering and systematic parameter optimization to achieve reliable results. Subsequent research by the Penthertz community further refined the technique, introducing the Pico Glitcher v3, a low-cost glitch generator based on the Raspberry Pi Pico that can achieve comparable results to much more expensive commercial equipment. The Pico Glitcher v3 incorporates a real-time power analysis trigger that can identify the IDCODE verification pattern and fire the glitch automatically, making the attack accessible to a much wider range of researchers and attackers. The ongoing evolution of RH850 hacking techniques demonstrates the principle that attacks only become easier and cheaper over time, as equipment improves and techniques are refined and shared. For the automotive industry, this means that a security mechanism that is adequate today may be inadequate in the future, and that continuous monitoring and updating of security measures is essential. The RH850 case also highlights the importance of collaboration between chip vendors, automotive manufacturers, and the security research community to identify and address vulnerabilities before they can be exploited by malicious actors.
The RH850/F1L voltage glitching attack occurs at a time of unprecedented transformation in the automotive industry, as vehicles become increasingly connected, automated, and electrified. Modern vehicles contain dozens of electronic control units (ECUs) that control everything from engine management and braking systems to infotainment and advanced driver assistance features, and the security of these ECUs has become a critical concern for both manufacturers and regulators. The UNECE R155 regulation, which came into effect in 2024, requires all new vehicle types to have a cybersecurity management system that covers the entire vehicle lifecycle, including physical security of ECUs. The RH850/F1L attack demonstrates that meeting this requirement requires more than just logical security measures; it requires robust physical security that can resist fault injection and other physical attacks. The automotive industry has historically been slow to adopt security best practices, in part because the development cycles for vehicles are long and the focus has traditionally been on functional safety rather than cybersecurity. However, high-profile demonstrations of remote vehicle hacking, combined with regulatory pressure, have accelerated the adoption of security measures in recent years. The RH850/F1L case also highlights the importance of the supply chain in automotive security, as ECUs are often designed and manufactured by tier-1 suppliers who may use microcontrollers from various chip vendors. Ensuring the security of the final vehicle requires coordination across the entire supply chain, from chip designers to ECU manufacturers to vehicle OEMs. The attack has also prompted Renesas to invest in improved security features for its automotive microcontroller families, including the RH850/U2A and RH850/E2x, which include dedicated hardware security modules, glitch detection circuits, and secure boot with hardware root of trust. These newer chips are designed to meet the ISO/SAE 21434 cybersecurity standard for automotive engineering, which provides a framework for managing cybersecurity risks in vehicle development. For automotive security researchers, the RH850/F1L attack has provided a valuable case study in the challenges of securing automotive microcontrollers against physical attacks, and it has spurred research into more robust fault injection countermeasures and detection techniques. The development of low-cost glitch generators such as the Pico Glitcher v3 has also made fault injection attacks more accessible, increasing the urgency for automotive manufacturers to address these vulnerabilities. The RH850/F1L case also has implications for vehicle forensics and law enforcement, as the ability to extract firmware from ECUs can be used to investigate accidents, identify tampering, and recover evidence from vehicle systems. As vehicles become more autonomous and as the value of the data they process continues to grow, the security of automotive microcontrollers will become increasingly important, and the lessons learned from the RH850/F1L attack will be essential for building the secure vehicles of the future. The case serves as a reminder that physical security is a critical component of automotive cybersecurity, and that chips designed for functional safety must also include robust security features to protect against deliberate physical attacks.
The RH850/F1L uses a 16-byte IDCODE password for debug authentication. Voltage glitching on the VCL pin bypasses the authentication check. Simple Power Analysis identifies the exact timing of the verification routine. The attack was demonstrated by Jerin Sunny and Shakir Zari in 2024. Success rate is approximately one in twenty attempts with optimal parameters. The VCL pin powers the CPU core and code flash directly. The attack affects automotive ECUs across multiple manufacturers. UNECE R155 requires physical security assessment for new vehicles. Renesas has improved security in newer RH850 families. The Pico Glitcher v3 provides low-cost equipment for this attack. SPA triggering makes the attack more reliable than fixed delays. The extracted firmware reveals calibration data and control algorithms. ECU cloning and counterfeiting are enabled by this attack. Automotive cybersecurity must include physical attack vectors. Functional safety does not automatically provide cybersecurity. The dual-core architecture does not prevent this attack. Physical tamper detection can provide additional protection. Secure elements can store keys outside the main MCU. This case highlights the convergence of safety and security. The lessons apply broadly to automotive microcontroller design.
The Renesas RH850/F1L voltage glitching attack demonstrates that even robust 16-byte password authentication can be bypassed through physical fault injection when the authentication check is performed by a CPU that is susceptible to glitching. By combining voltage glitching with simple power analysis for precise triggering, researchers were able to reliably defeat the IDCODE mechanism and extract firmware from automotive ECUs. This case study underscores the critical importance of physical security in automotive systems, the limitations of password-based authentication when physical access is available, and the need for defense-in-depth strategies that combine chip-level hardening, system-level tamper protection, and application-level security. As vehicles become increasingly connected and automated, and as the value of automotive firmware and data continues to grow, the lessons learned from the RH850/F1L attack will be essential for building the next generation of secure automotive systems. The ongoing evolution of attack techniques, from DIY glitchers to sophisticated side-channel-triggered fault injection, ensures that automotive cybersecurity will remain a dynamic and challenging field for years to come.