Membership Inference Attacks Beyond Overfitting

Fuente: arXiv
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Autores principales: Khalil, Mona, Blanco-Justicia, Alberto, Jebreel, Najeeb, Domingo-Ferrer, Josep
Formato: Preprint
Publicado: 2025
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author Khalil, Mona
Blanco-Justicia, Alberto
Jebreel, Najeeb
Domingo-Ferrer, Josep
author_facet Khalil, Mona
Blanco-Justicia, Alberto
Jebreel, Najeeb
Domingo-Ferrer, Josep
contents Membership inference attacks (MIAs) against machine learning (ML) models aim to determine whether a given data point was part of the model training data. These attacks may pose significant privacy risks to individuals whose sensitive data were used for training, which motivates the use of defenses such as differential privacy, often at the cost of high accuracy losses. MIAs exploit the differences in the behavior of a model when making predictions on samples it has seen during training (members) versus those it has not seen (non-members). Several studies have pointed out that model overfitting is the major factor contributing to these differences in behavior and, consequently, to the success of MIAs. However, the literature also shows that even non-overfitted ML models can leak information about a small subset of their training data. In this paper, we investigate the root causes of membership inference vulnerabilities beyond traditional overfitting concerns and suggest targeted defenses. We empirically analyze the characteristics of the training data samples vulnerable to MIAs in models that are not overfitted (and hence able to generalize). Our findings reveal that these samples are often outliers within their classes (e.g., noisy or hard to classify). We then propose potential defensive strategies to protect these vulnerable samples and enhance the privacy-preserving capabilities of ML models. Our code is available at https://github.com/najeebjebreel/mia_analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2511_16792
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Membership Inference Attacks Beyond Overfitting
Khalil, Mona
Blanco-Justicia, Alberto
Jebreel, Najeeb
Domingo-Ferrer, Josep
Cryptography and Security
Machine Learning
Membership inference attacks (MIAs) against machine learning (ML) models aim to determine whether a given data point was part of the model training data. These attacks may pose significant privacy risks to individuals whose sensitive data were used for training, which motivates the use of defenses such as differential privacy, often at the cost of high accuracy losses. MIAs exploit the differences in the behavior of a model when making predictions on samples it has seen during training (members) versus those it has not seen (non-members). Several studies have pointed out that model overfitting is the major factor contributing to these differences in behavior and, consequently, to the success of MIAs. However, the literature also shows that even non-overfitted ML models can leak information about a small subset of their training data. In this paper, we investigate the root causes of membership inference vulnerabilities beyond traditional overfitting concerns and suggest targeted defenses. We empirically analyze the characteristics of the training data samples vulnerable to MIAs in models that are not overfitted (and hence able to generalize). Our findings reveal that these samples are often outliers within their classes (e.g., noisy or hard to classify). We then propose potential defensive strategies to protect these vulnerable samples and enhance the privacy-preserving capabilities of ML models. Our code is available at https://github.com/najeebjebreel/mia_analysis.
title Membership Inference Attacks Beyond Overfitting
topic Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2511.16792