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Xiaobei Yan

Publications and source records attributed to Xiaobei Yan.

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ObfusBFA: A Holistic Approach to Safeguarding DNNs from Different Types of Bit-Flip Attacks

Bit-flip attacks (BFAs) represent a serious threat to Deep Neural Networks (DNNs), where flipping a small number of bits in the model parameters or binary code can significantly degrade the model accuracy or mislead the model prediction in a desired way. Existing defenses exclusively focus on protecting models for specific attacks and platforms, while lacking effectiveness for other scenarios. We propose ObfusBFA, an efficient and holistic methodology to mitigate BFAs targeting both the high-level model weights and low-level codebase (executables or shared libraries). The key idea of ObfusBFA is to introduce random dummy operations during the model inference, which effectively transforms the delicate attacks into random bit flips, making it much harder for attackers to pinpoint and exploit vulnerable bits. We design novel algorithms to identify critical bits and insert obfuscation operations. We evaluate ObfusBFA against different types of attacks, including the adaptive scenarios where the attacker increases the flip bit budget to attempt to circumvent our defense. The results show that ObfusBFA can consistently preserve the model accuracy across various datasets and DNN architectures while significantly reducing the attack success rates. Additionally, it introduces minimal latency and storage overhead, making it a practical solution for real-world applications.

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BitHydra: Towards Bit-flip Inference Cost Attack against Large Language Models

Large language models (LLMs) are widely deployed, but their substantial compute demands make them vulnerable to inference cost attacks that aim to deliberately maximize the output length. In this work, we investigate a distinct attack surface: maximizing inference cost by tampering with the model parameters instead of inputs. This approach leverages the established capability of Bit-Flip Attacks (BFAs) to persistently alter model behavior via minute weight perturbations, effectively decoupling the attack from specific input queries. To realize this, we propose BitHydra, a framework that addresses the unique optimization challenge of identifying the exact weight bits that maximize generation cost. We formulate the attack as a constrained Binary Integer Programming (BIP) problem designed to systematically suppress the end-of-sequence (i.e., ) probability. To overcome the intractability of the discrete search space, we relax the problem into a continuous optimization task and solve it via the Alternating Direction Method of Multipliers (ADMM). We evaluate BitHydra across 10 LLMs (1.5B-16B). Our results demonstrate that the proposed optimization method efficiently achieves endless generation with as few as 1-4 bit flips on all testing models, verifying the effectiveness of the ADMM-based formulation against both standard models and potential defenses.

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Defense against ML-based Power Side-channel Attacks on DNN Accelerators with Adversarial Attacks

Artificial Intelligence (AI) hardware accelerators have been widely adopted to enhance the efficiency of deep learning applications. However, they also raise security concerns regarding their vulnerability to power side-channel attacks (SCA). In these attacks, the adversary exploits unintended communication channels to infer sensitive information processed by the accelerator, posing significant privacy and copyright risks to the models. Advanced machine learning algorithms are further employed to facilitate the side-channel analysis and exacerbate the privacy issue of AI accelerators. Traditional defense strategies naively inject execution noise to the runtime of AI models, which inevitably introduce large overheads. In this paper, we present AIAShield, a novel defense methodology to safeguard FPGA-based AI accelerators and mitigate model extraction threats via power-based SCAs. The key insight of AIAShield is to leverage the prominent adversarial attack technique from the machine learning community to craft delicate noise, which can significantly obfuscate the adversary's side-channel observation while incurring minimal overhead to the execution of the protected model. At the hardware level, we design a new module based on ring oscillators to achieve fine-grained noise generation. At the algorithm level, we repurpose Neural Architecture Search to worsen the adversary's extraction results. Extensive experiments on the Nvidia Deep Learning Accelerator (NVDLA) demonstrate that AIAShield outperforms existing solutions with excellent transferability.

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A Unified Hardware-based Threat Detector for AI Accelerators

The proliferation of AI technology gives rise to a variety of security threats, which significantly compromise the confidentiality and integrity of AI models and applications. Existing software-based solutions mainly target one specific attack, and require the implementation into the models, rendering them less practical. We design UniGuard, a novel unified and non-intrusive detection methodology to safeguard FPGA-based AI accelerators. The core idea of UniGuard is to harness power side-channel information generated during model inference to spot any anomaly. We employ a Time-to-Digital Converter to capture power fluctuations and train a supervised machine learning model to identify various types of threats. Evaluations demonstrate that UniGuard can achieve 94.0% attack detection accuracy, with high generalization over unknown or adaptive attacks and robustness against varied configurations (e.g., sensor frequency and location).

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Mercury: An Automated Remote Side-channel Attack to Nvidia Deep Learning Accelerator

DNN accelerators have been widely deployed in many scenarios to speed up the inference process and reduce the energy consumption. One big concern about the usage of the accelerators is the confidentiality of the deployed models: model inference execution on the accelerators could leak side-channel information, which enables an adversary to preciously recover the model details. Such model extraction attacks can not only compromise the intellectual property of DNN models, but also facilitate some adversarial attacks. Although previous works have demonstrated a number of side-channel techniques to extract models from DNN accelerators, they are not practical for two reasons. (1) They only target simplified accelerator implementations, which have limited practicality in the real world. (2) They require heavy human analysis and domain knowledge. To overcome these limitations, this paper presents Mercury, the first automated remote side-channel attack against the off-the-shelf Nvidia DNN accelerator. The key insight of Mercury is to model the side-channel extraction process as a sequence-to-sequence problem. The adversary can leverage a time-to-digital converter (TDC) to remotely collect the power trace of the target model's inference. Then he uses a learning model to automatically recover the architecture details of the victim model from the power trace without any prior knowledge. The adversary can further use the attention mechanism to localize the leakage points that contribute most to the attack. Evaluation results indicate that Mercury can keep the error rate of model extraction below 1%.

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