UOR: Universal Backdoor Attacks on Pre-trained Language Models

Fuente: arXiv
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Hauptverfasser: Du, Wei, Li, Peixuan, Li, Boqun, Zhao, Haodong, Liu, Gongshen
Format: Preprint
Veröffentlicht: 2023
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author Du, Wei
Li, Peixuan
Li, Boqun
Zhao, Haodong
Liu, Gongshen
author_facet Du, Wei
Li, Peixuan
Li, Boqun
Zhao, Haodong
Liu, Gongshen
contents Backdoors implanted in pre-trained language models (PLMs) can be transferred to various downstream tasks, which exposes a severe security threat. However, most existing backdoor attacks against PLMs are un-targeted and task-specific. Few targeted and task-agnostic methods use manually pre-defined triggers and output representations, which prevent the attacks from being more effective and general. In this paper, we first summarize the requirements that a more threatening backdoor attack against PLMs should satisfy, and then propose a new backdoor attack method called UOR, which breaks the bottleneck of the previous approach by turning manual selection into automatic optimization. Specifically, we define poisoned supervised contrastive learning which can automatically learn the more uniform and universal output representations of triggers for various PLMs. Moreover, we use gradient search to select appropriate trigger words which can be adaptive to different PLMs and vocabularies. Experiments show that our method can achieve better attack performance on various text classification tasks compared to manual methods. Further, we tested our method on PLMs with different architectures, different usage paradigms, and more difficult tasks, which demonstrated the universality of our method.
format Preprint
id arxiv_https___arxiv_org_abs_2305_09574
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle UOR: Universal Backdoor Attacks on Pre-trained Language Models
Du, Wei
Li, Peixuan
Li, Boqun
Zhao, Haodong
Liu, Gongshen
Computation and Language
Artificial Intelligence
Cryptography and Security
Backdoors implanted in pre-trained language models (PLMs) can be transferred to various downstream tasks, which exposes a severe security threat. However, most existing backdoor attacks against PLMs are un-targeted and task-specific. Few targeted and task-agnostic methods use manually pre-defined triggers and output representations, which prevent the attacks from being more effective and general. In this paper, we first summarize the requirements that a more threatening backdoor attack against PLMs should satisfy, and then propose a new backdoor attack method called UOR, which breaks the bottleneck of the previous approach by turning manual selection into automatic optimization. Specifically, we define poisoned supervised contrastive learning which can automatically learn the more uniform and universal output representations of triggers for various PLMs. Moreover, we use gradient search to select appropriate trigger words which can be adaptive to different PLMs and vocabularies. Experiments show that our method can achieve better attack performance on various text classification tasks compared to manual methods. Further, we tested our method on PLMs with different architectures, different usage paradigms, and more difficult tasks, which demonstrated the universality of our method.
title UOR: Universal Backdoor Attacks on Pre-trained Language Models
topic Computation and Language
Artificial Intelligence
Cryptography and Security
url https://arxiv.org/abs/2305.09574