What Is Power/Clock/Reset Glitching? Fault Injection Explained for Cybersecurity

Introduction

In the realm of hardware hacking and embedded system security, Power/Clock/Reset Glitching stands out as one of the most effective attack vectors for bypassing system protections. These fault injection techniques are used to momentarily disrupt the normal operation of a device, tricking it into behaving in unintended ways. Attackers use glitching to bypass authentication, extract secret keys, or hijack firmware processes—all without physically altering the device.

Whether you’re a cybersecurity researcher, embedded system engineer, or aspiring ethical hacker, understanding Power, Clock, and Reset glitching is critical to uncovering vulnerabilities in hardware.

 What Is Glitching in Cybersecurity?

Glitching, in cybersecurity and hardware penetration testing, refers to introducing brief, unexpected changes in a device's power, clock, or reset signals to disrupt its normal execution. These “fault injections” can help bypass security checks and trigger exploitable behavior in the system.

 Why Is Glitching So Effective?

Many secure systems rely on strict timing and predictable voltage levels. If you momentarily cause a fault at precisely the right moment, you can:

• Skip security verification routines

• Execute unauthorized code

• Extract cryptographic keys

• Crash the system into a debug or unprotected state

  
  

Since the glitch doesn’t permanently damage the hardware, attackers can repeatedly experiment until they achieve the desired result.

 Types of Glitching Attacks

Glitching generally falls under three categories, based on which part of the system signal is targeted:

1. Power Glitching

This involves momentarily altering the device's power supply. For example, dropping the voltage briefly may corrupt critical operations like memory access or key verification routines.

Use Cases:

• Bypassing password checks

• Crashing bootloaders into insecure modes

2. Clock Glitching

In this technique, an attacker introduces a malformed or sped-up clock pulse. Since most embedded systems use clock cycles to execute operations, modifying the clock at the right moment can force the system to skip or mis-execute instructions.

Use Cases:

• Skipping condition checks

• Gaining unauthorized access during secure boot

3. Reset Glitching

Reset glitching involves sending malformed reset pulses to the device. Instead of a clean restart, the system may partially reset, entering unpredictable or insecure states.

Use Cases:

• Triggering a debug mode unintentionally

• Gaining access to boot ROM

 How Glitching Is Performed

To perform glitching attacks, security researchers typically use hardware fault injection platforms such as:

• ChipWhisperer: An open-source toolkit for side-channel and glitching attacks

• Glitcher boards: Custom-built boards to manipulate power or clock lines

• Oscilloscopes and logic analyzers: For precise timing and monitoring

The general process is:

1. Connect target device to glitching hardware

2. Identify target event (e.g., boot, password check)

3. Time the glitch using side-channel analysis or trial-and-error

4. Trigger the glitch and monitor for unexpected behavior

 Common Targets of Glitching Attacks

Glitching is used against devices with:

• Microcontrollers and SoCs

• Secure bootloaders

• Smartcards

• Trusted Platform Modules (TPMs)

• Encrypted firmware

Devices such as routers, payment terminals, automotive ECUs, and IoT devices are especially vulnerable.

Real-World Examples of Glitching Attacks

 PlayStation 3 Jailbreak (2010)

Researchers used power glitching to bypass security features in the PlayStation 3’s boot process, allowing users to run unsigned code.

 Crypto IC Fault Injection

Smartcards used for payment and cryptographic applications have been broken using precise glitching attacks to extract RSA/DSA private keys.

 Power vs Clock vs Reset Glitching – What's the Difference?

 What Makes Devices Vulnerable to Glitching?

1. Lack of signal filtering: Poorly designed boards don’t filter voltage or clock variations.

2. No tamper detection: Secure chips should detect fault injections and halt.

3. Unprotected bootloaders: Older or insecure firmware is easier to bypass.

4. No redundancy or integrity checks: Systems that don’t validate execution paths are more vulnerable.

 How Can You Defend Against Glitching?

Mitigating glitching attacks requires both hardware and software-level protections:

Hardware Countermeasures:

• Voltage and clock filtering

• Tamper detection circuits

• Integrated glitch detectors

Software Defenses:

• Redundant checks (e.g., double-verify passwords)

• Delay loops and entropy-based timing

• Secure boot verification with cryptographic validation

 Who Uses Glitching?

Glitching is widely used by:

• Red Teamers and Penetration Testers

• Reverse Engineers

• Hardware Security Researchers

• Nation-state Actors targeting embedded or IoT devices

It's not just for malicious use—ethical hackers and security analysts use glitching to test the robustness of critical infrastructure.

 Learn Glitching Techniques

For those interested in practical training:

• Study courses in embedded hardware hacking

• Use platforms like ChipWhisperer to simulate attacks

• Participate in hardware capture-the-flag (CTF) challenges

Conclusion

Power/Clock/Reset glitching is a powerful technique in the hands of those who understand the nuances of embedded system behavior. While it requires precision and experimentation, successful glitching can reveal critical flaws in devices that otherwise appear secure. As more systems integrate hardware-based security, knowledge of glitching will remain a key skill in offensive and defensive cybersecurity.

FAQs 

What is glitching in cybersecurity?

Glitching is a fault injection technique used to disrupt a system’s normal operations by altering its power, clock, or reset signals momentarily.

How does power glitching work?

Power glitching involves a brief drop or spike in voltage that causes a device to skip or misprocess certain instructions.

What is clock glitching?

Clock glitching introduces irregular pulses into a device’s clock signal to confuse its instruction execution.

What is reset glitching?

Reset glitching manipulates the reset signal of a device, potentially forcing it into insecure or unexpected states.

Why is glitching used in cybersecurity?

Glitching is used to bypass security checks, extract keys, or trigger insecure system behavior without physically tampering with the device.

Who uses power/clock/reset glitching techniques?

These techniques are used by red teamers, ethical hackers, reverse engineers, and nation-state actors.

Can glitching attacks damage the hardware?

When done correctly, glitching doesn’t damage hardware, but excessive or uncontrolled attempts can cause harm.

What devices are vulnerable to glitching?

Microcontrollers, embedded systems, smartcards, IoT devices, and bootloaders are commonly vulnerable.

What tools are used for glitching attacks?

Common tools include ChipWhisperer, glitcher boards, oscilloscopes, and custom pulse injectors.

Is glitching legal?

It is legal in a controlled, ethical hacking or research environment but illegal if used for malicious purposes.

What is the purpose of glitching in security research?

Researchers use glitching to find vulnerabilities in embedded systems and improve hardware security.

Can glitching bypass secure boot?

Yes, glitching can be used to bypass secure boot by disrupting verification steps during boot-up.

How does power glitching bypass password checks?

A well-timed power glitch can cause a system to skip over the code responsible for password validation.

What is a real-world example of clock glitching?

Clock glitching has been used in console hacking, such as bypassing security in the PlayStation 3.

What does a glitcher board do?

A glitcher board injects precise voltage or timing disturbances into the system to induce faults.

How precise must a glitching attack be?

Glitching requires extreme precision, often down to microseconds or nanoseconds, to succeed.

Can glitching extract cryptographic keys?

Yes, fault injection techniques like glitching have been used to extract private keys from hardware.

What is ChipWhisperer?

ChipWhisperer is an open-source platform used for power analysis and glitching in hardware security research.

How does glitching relate to side-channel attacks?

Both glitching and side-channel attacks target physical implementation flaws, but glitching introduces faults while side-channels observe leakage.

Is glitching detectable by the target device?

Advanced systems may include glitch detectors, but many consumer and industrial devices do not.

How can you defend against glitching attacks?

Mitigations include voltage filters, tamper-proof circuits, redundant checks, and secure boot mechanisms.

What is the difference between glitching and brute force?

Glitching manipulates system behavior, while brute force relies on repeated password guessing or code attempts.

What is timing in glitching attacks?

Timing refers to executing the glitch at the precise instruction cycle to achieve a specific system failure.

How does glitching affect firmware?

Glitching may bypass firmware security routines or allow access to protected memory regions.

Can glitching be used on mobile devices?

Yes, if you have physical access to internal circuits, mobile SoCs can be targeted with glitching.

Is glitching effective against TPM chips?

Yes, with advanced tools, TPM and HSM chips can be vulnerable to power or clock fault attacks.

Can glitching trigger debug mode?

Reset glitching can sometimes cause a system to enter debug or development mode unintentionally.

How does glitching help in reverse engineering?

It allows temporary access to protected code or data, aiding in analysis and vulnerability research.

Can glitching bypass encryption?

While it doesn’t break encryption, glitching can sometimes skip or disable the logic that enforces encryption.

Is glitching taught in ethical hacking courses?

Yes, advanced hardware security and ethical hacking courses often cover glitching techniques and tools.