Strategic Sample Selection for Improved Clean-Label Backdoor Attacks in Text Classification

Fuente: arXiv
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Main Authors: Kirci, Onur Alp, Gursoy, M. Emre
Format: Preprint
Published: 2025
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author Kirci, Onur Alp
Gursoy, M. Emre
author_facet Kirci, Onur Alp
Gursoy, M. Emre
contents Backdoor attacks pose a significant threat to the integrity of text classification models used in natural language processing. While several dirty-label attacks that achieve high attack success rates (ASR) have been proposed, clean-label attacks are inherently more difficult. In this paper, we propose three sample selection strategies to improve attack effectiveness in clean-label scenarios: Minimum, Above50, and Below50. Our strategies identify those samples which the model predicts incorrectly or with low confidence, and by injecting backdoor triggers into such samples, we aim to induce a stronger association between the trigger patterns and the attacker-desired target label. We apply our methods to clean-label variants of four canonical backdoor attacks (InsertSent, WordInj, StyleBkd, SynBkd) and evaluate them on three datasets (IMDB, SST2, HateSpeech) and four model types (LSTM, BERT, DistilBERT, RoBERTa). Results show that the proposed strategies, particularly the Minimum strategy, significantly improve the ASR over random sample selection with little or no degradation in the model's clean accuracy. Furthermore, clean-label attacks enhanced by our strategies outperform BITE, a state of the art clean-label attack method, in many configurations.
format Preprint
id arxiv_https___arxiv_org_abs_2508_15934
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strategic Sample Selection for Improved Clean-Label Backdoor Attacks in Text Classification
Kirci, Onur Alp
Gursoy, M. Emre
Cryptography and Security
Artificial Intelligence
Machine Learning
Backdoor attacks pose a significant threat to the integrity of text classification models used in natural language processing. While several dirty-label attacks that achieve high attack success rates (ASR) have been proposed, clean-label attacks are inherently more difficult. In this paper, we propose three sample selection strategies to improve attack effectiveness in clean-label scenarios: Minimum, Above50, and Below50. Our strategies identify those samples which the model predicts incorrectly or with low confidence, and by injecting backdoor triggers into such samples, we aim to induce a stronger association between the trigger patterns and the attacker-desired target label. We apply our methods to clean-label variants of four canonical backdoor attacks (InsertSent, WordInj, StyleBkd, SynBkd) and evaluate them on three datasets (IMDB, SST2, HateSpeech) and four model types (LSTM, BERT, DistilBERT, RoBERTa). Results show that the proposed strategies, particularly the Minimum strategy, significantly improve the ASR over random sample selection with little or no degradation in the model's clean accuracy. Furthermore, clean-label attacks enhanced by our strategies outperform BITE, a state of the art clean-label attack method, in many configurations.
title Strategic Sample Selection for Improved Clean-Label Backdoor Attacks in Text Classification
topic Cryptography and Security
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2508.15934