Guarding against the threat of clock attacks with analog IP

By Chris Morrison, VP Product Marketing

February 27, 2025

This Agile Analog blog post focuses on clock attacks and how clock attack monitors can help detect them. As system-on-chip (SoC) security threats grow even more sophisticated, attackers are increasingly targeting the clock system to manipulate execution timing and generate faults. By physically altering the clock signals, they can compromise cryptographic operations, bypass security mechanisms, or force a system change. Four primary techniques are used in physical clock attacks: clock glitching, frequency changing, single stepping, and duty cycle manipulation. The aim is to disrupt the normal operation of an electronics system by introducing malfunctions in order to exploit vulnerabilities or extract sensitive information.

The challenges with clock attacks

Software-based attacks are well documented, with established detection and countermeasures. However, hardware-level attacks, such as clock manipulation, remain more challenging to identify. There may be no immediately obvious indications of tampering so the impact might only become apparent after an extended period of time. Clock attacks specifically target low-level hardware components such as microcontrollers, cryptographic chips and processors. These often lack the same degree of monitoring and protection as higher-level software, making them more vulnerable to manipulation.

The impact of clock attacks

Clock attacks can have severe consequences, including system instability, security breaches, and also physical harm in security and safety-critical applications.

Data loss and corruption: Even minor disruptions to the clock signal can lead to data loss and corruption. Many embedded systems rely on precise timing, and a successful attack can force errors that compromise sensitive data.

System failure: Modern processors often require tightly controlled timings to ensure the correct process flow and execution of instructions. By glitching the clock, an attacker can introduce errors into processes that result in system failure or damage.

Safety risks: IoT devices have real-time constraints, where timing deviations can disrupt critical functions. A clock attack on a smart medical device, for example, could alter dosage calculations or deactivate life-saving monitoring systems.

Cryptographic vulnerabilities: encryption and key management depend on accurate timing for secure operations. If an attacker manipulates the clock, this can weaken cryptographic defenses and potentially allow encryption keys to be stolen.

Hardware compromise: Devices with secure boot mechanisms count on controlled timing to validate and load trusted firmware. By performing clock glitches at the right moment, an attacker could bypass security checks and upload malicious firmware.

Clock attacks are an active and growing concern. Without proper countermeasures, these vulnerabilities can be exploited to compromise critical systems, from payment cards to automotive control units. Given these risks, organizations must implement ways to detect and respond to clock-based tampering. This is where clock attack monitors play a crucial role in guarding embedded and cryptographic systems.

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