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Breaking Neural Networks ⚡ How Clock Glitch Attacks Threaten AI and What We Can Do About It

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Exploring Fault Injection Attacks on Deep Neural Networks and the Ingenious Countermeasures to Protect Them 🔧🤖

Published May 11, 2025 By EngiSphere Research Editors
Illustration of Neural Network Diagram with Subtle Clock Glitch Effects © AI Illustration
Illustration of Neural Network Diagram with Subtle Clock Glitch Effects © AI Illustration

The Main Idea

This research demonstrates how clock glitch fault attacks can effectively induce misclassifications in deep neural network models deployed on microcontrollers, and proposes algorithmic countermeasures to detect and prevent such attacks with minimal computational overhead.


The R&D

Today, we’re exploring a groundbreaking study that reveals how clock glitch fault attacks can disrupt deep neural networks (DNNs) and what researchers are doing to stop them. If you’ve ever wondered about the vulnerabilities of AI systems in edge devices, this is the article for you! Let’s get started. 🚀

What Are Deep Neural Networks, and Why Should You Care? 🤔

DNNs are fundamental to the architecture of modern artificial intelligence (AI). From autonomous vehicles 🚗 to smart home devices 🏠, DNNs are everywhere. They excel at tasks like image recognition, natural language processing, and more. But here’s the catch: when DNNs are deployed on edge devices—like microcontrollers in IoT gadgets—they become vulnerable to malicious attacks. 😱

One such attack is the fault injection attack, where attackers deliberately introduce errors into the system to cause misclassification or extract sensitive information. In this study, researchers from Hoseo University and Coontec Co., Ltd., focused on clock glitch fault attacks —a low-cost, high-impact method of disrupting DNN operations.

The Study: Clock Glitch Attacks on DNNs ⏰💻
What Are Clock Glitch Fault Attacks?

Imagine you’re running a marathon 🏃‍♂️, and someone suddenly changes the rhythm of your steps. You’d stumble, right? That’s essentially what a clock glitch fault attack does to a microcontroller. By tampering with the timing of the device’s clock signal, attackers can cause instructions to skip or malfunction, leading to incorrect outputs.

In this study, the researchers targeted the Softmax and Sigmoid functions in the output layers of DNN models. These functions are crucial because they convert raw data into probabilities for classification tasks. For example:

  • Softmax: Used in multi-class classification (e.g., identifying digits 0–9).
  • Sigmoid: Used in binary classification (e.g., distinguishing cats from dogs).

By injecting clock glitches during these critical operations, the researchers demonstrated how attackers could induce serious misclassifications . 😨

How Did They Conduct the Experiment? 🔬

The team used a 32-bit STM32F303 microcontroller to implement their DNN models. They tested two types of datasets:

  1. MNIST Dataset: Handwritten digits (0–9) for multi-class classification.
  2. CIFAR-10 and Kaggle Datasets: Color images for multi-class and binary classification.

They also employed a pattern-matching algorithm called the Sum of Absolute Differences (SAD) to determine the exact timing for injecting glitches. This ensured that the attacks were realistic and replicable in real-world scenarios.

The Results: Misclassification Galore! 📊

The findings were alarming:

  • Multi-Class Classification: The accuracy of the MLP model dropped from 95.88% to 16.09% after the attack.
  • Binary Classification: Accuracy plummeted from 100% to just 1.2%!

Even more concerning, the attack worked across various DNN architectures, including popular models like InceptionNet , ResNet , and VGGNet. For instance:

  • InceptionNet’s accuracy on CIFAR-10 fell from 91.66% to 10.61%.
  • On the Kaggle Dogs vs. Cats dataset, ResNet’s accuracy dropped from 91% to 4.4%.

These results highlight how effective clock glitch attacks can be in compromising DNN-based systems. 🚨

Why Is This Important? 🌍

Fault injection attacks are not merely theoretical; they pose actual threats. For example:

  • Autonomous Vehicles: Misclassifying road signs or pedestrians could lead to catastrophic accidents. 🚧
  • Smart Homes: Hackers could bypass authentication mechanisms, gaining unauthorized access to your devices. 🔓
  • Healthcare: Medical imaging systems relying on DNNs might produce incorrect diagnoses, endangering lives. ⚕️

The simplicity and low cost of clock glitch attacks make them particularly dangerous. Attackers don’t need expensive equipment; they can use basic tools to exploit vulnerabilities in embedded systems.

Countermeasures: Fighting Back Against Fault Attacks 🛡️

Thankfully, the researchers didn’t stop at exposing the problem—they proposed ingenious countermeasures to protect DNNs. Here’s how they tackled the issue:

1. Softmax Function Protection

The team introduced three checks to ensure the Softmax function operates correctly:

  • Verify that all loops execute fully.
  • Confirm that the sum of probabilities equals 1 (as it should in Softmax).
  • Detect anomalies in memory values caused by faults.

These measures increased computational overhead slightly but effectively detected 92.56% of injected faults . 🎯

2. Sigmoid Function Protection

For binary classification, the researchers applied the inverse function of Sigmoid to validate outputs. If the output doesn’t match the expected input, the system flags it as faulty. This method achieved 100% detection of injected faults. ✅

Performance Impact

While the countermeasures added some computational overhead (about 88% increase in execution time), the trade-off is negligible compared to the benefits of enhanced security. Plus, these methods require minimal additional memory, making them ideal for resource-constrained IoT devices. 💻💪

Future Prospects: Where Do We Go From Here? 🌟

This work paves the way for compelling future investigations:

  • Broader Hardware Testing: While the experiments focused on the STM32F303 microcontroller, similar studies should explore other architectures like RISC-V, x86, and FPGA-based systems.
  • Advanced Attack Vectors: Researchers should investigate non-contact methods like laser or electromagnetic (EM) fault injection, which pose unique challenges.
  • Integrated Security Solutions: Combining hardware-level protections with software-based countermeasures could provide robust defense mechanisms against diverse attack vectors.

Moreover, as AI continues to permeate every aspect of our lives, securing these systems becomes paramount. Engineers, developers, and policymakers must work together to create standards and frameworks that safeguard AI technologies. 🤝

Final Thoughts: Stay Curious, Stay Secure! 🔍💡

Clock glitch fault attacks are a wake-up call for the engineering community. They remind us that even the most advanced AI systems are not immune to vulnerabilities. However, with innovative solutions like the ones proposed in this study, we can build safer, more resilient systems.

As always, thank you for joining us on this journey through cutting-edge engineering research. If you found this article insightful, share it with your fellow tech enthusiasts!✨

Key Takeaways 📝
  • Clock glitch attacks can severely disrupt DNN operations, leading to misclassifications.
  • The Softmax and Sigmoid functions are particularly vulnerable targets.
  • Proposed countermeasures detect up to 92.56% of faults with minimal overhead.
  • Future research should focus on broader hardware testing and integrated security solutions.

Let’s keep pushing the boundaries of innovation while ensuring our technologies remain secure. 🌐🛡️


Concepts to Know

Deep Neural Networks (DNNs) 🧠 DNNs are like the "brain" of AI systems. They’re made up of layers of interconnected "neurons" that learn patterns from data to perform tasks like image recognition or speech processing. - More about this concept in the article "Revolutionizing UAV Networks with AI: Smarter Task Assignment for a Dynamic World 📡 🚁".

Clock Glitch Fault Attacks ⏰🚨 Imagine messing with the heartbeat of a device to make it skip a beat. Clock glitch attacks tamper with the timing of a microcontroller’s clock signal, causing errors in its operations—like making a neural network misclassify images.

Softmax Function 🔢📊 The Softmax function is like a "probability calculator" in AI models. It takes raw numbers from the neural network and turns them into probabilities for each class, helping the model decide what it’s seeing (e.g., "This is 90% likely a cat").

Sigmoid Function 📈 The Sigmoid function is a simpler cousin of Softmax. It squishes any input value between 0 and 1, making it perfect for binary decisions like "Is this a cat (1) or not (0)?"

Fault Injection Attacks 💥🕵️‍♂️ These are sneaky tricks where attackers intentionally introduce errors (faults) into a system to mess with its behavior. Think of it as hacking by causing tiny malfunctions.

Sum of Absolute Differences (SAD) 🔍📈 SAD is a clever way to match patterns. It compares two signals by measuring how different they are at each point. If the difference is small enough, it means they’re a match!

Countermeasures 🛡️🔧 These are the "defensive shields" engineers use to protect systems from attacks. In this case, countermeasures are added steps in the algorithm to detect and stop glitches before they cause harm.


Source: Lee, S.; Kim, S.; Hong, S.; Ha, J. Clock Glitch Fault Attacks on Deep Neural Networks and Their Countermeasures. Sensors 2025, 25, 2793. https://doi.org/10.3390/s25092793

From: Hoseo University; Coontec Co., Ltd..

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