Revisiting Character-level Adversarial Attacks for Language Models

Fuente: arXiv
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Auteurs principaux: Rocamora, Elias Abad, Wu, Yongtao, Liu, Fanghui, Chrysos, Grigorios G., Cevher, Volkan
Format: Preprint
Publié: 2024
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author Rocamora, Elias Abad
Wu, Yongtao
Liu, Fanghui
Chrysos, Grigorios G.
Cevher, Volkan
author_facet Rocamora, Elias Abad
Wu, Yongtao
Liu, Fanghui
Chrysos, Grigorios G.
Cevher, Volkan
contents Adversarial attacks in Natural Language Processing apply perturbations in the character or token levels. Token-level attacks, gaining prominence for their use of gradient-based methods, are susceptible to altering sentence semantics, leading to invalid adversarial examples. While character-level attacks easily maintain semantics, they have received less attention as they cannot easily adopt popular gradient-based methods, and are thought to be easy to defend. Challenging these beliefs, we introduce Charmer, an efficient query-based adversarial attack capable of achieving high attack success rate (ASR) while generating highly similar adversarial examples. Our method successfully targets both small (BERT) and large (Llama 2) models. Specifically, on BERT with SST-2, Charmer improves the ASR in 4.84% points and the USE similarity in 8% points with respect to the previous art. Our implementation is available in https://github.com/LIONS-EPFL/Charmer.
format Preprint
id arxiv_https___arxiv_org_abs_2405_04346
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Revisiting Character-level Adversarial Attacks for Language Models
Rocamora, Elias Abad
Wu, Yongtao
Liu, Fanghui
Chrysos, Grigorios G.
Cevher, Volkan
Machine Learning
Artificial Intelligence
Computation and Language
Adversarial attacks in Natural Language Processing apply perturbations in the character or token levels. Token-level attacks, gaining prominence for their use of gradient-based methods, are susceptible to altering sentence semantics, leading to invalid adversarial examples. While character-level attacks easily maintain semantics, they have received less attention as they cannot easily adopt popular gradient-based methods, and are thought to be easy to defend. Challenging these beliefs, we introduce Charmer, an efficient query-based adversarial attack capable of achieving high attack success rate (ASR) while generating highly similar adversarial examples. Our method successfully targets both small (BERT) and large (Llama 2) models. Specifically, on BERT with SST-2, Charmer improves the ASR in 4.84% points and the USE similarity in 8% points with respect to the previous art. Our implementation is available in https://github.com/LIONS-EPFL/Charmer.
title Revisiting Character-level Adversarial Attacks for Language Models
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2405.04346