Erased but Not Forgotten: How Backdoors Compromise Concept Erasure

Fuente: arXiv
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Auteurs principaux: Braun, Tobias, Grebe, Jonas Henry, Rohrbach, Marcus, Rohrbach, Anna
Format: Preprint
Publié: 2025
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author Braun, Tobias
Grebe, Jonas Henry
Rohrbach, Marcus
Rohrbach, Anna
author_facet Braun, Tobias
Grebe, Jonas Henry
Rohrbach, Marcus
Rohrbach, Anna
contents The expansion of text-to-image diffusion models has raised concerns about harmful outputs, from fabricated depictions of public figures to sexually explicit imagery. To mitigate such risks, prior work has proposed concept erasure methods that aim to sever unwanted concepts from the model via fine-tuning, yet it remains unclear whether these approaches truly remove all links to the harmful concept or merely conceal superficial connections. In this work, we reveal a critical vulnerability, the Erasure Evasion Backdoor (EEB): an adversary binds a backdoor trigger to a concept slated for removal, and this malicious link survives subsequent erasure. We show that both black-box and white-box adversaries can instantiate this threat. Across six state-of-the-art erasure methods, including robust ones that explicitly search for alternative representations of the target concept, EEB consistently exposes harmful content: up to 82% success against celebrity-identity unlearning, up to 94% for object erasure, and up to 16 times amplification of explicit-content exposure. While EEB uncovers a blind spot in current erasure methods, it also provides a diagnostic tool for stress-testing future concept erasure techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2504_21072
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Erased but Not Forgotten: How Backdoors Compromise Concept Erasure
Braun, Tobias
Grebe, Jonas Henry
Rohrbach, Marcus
Rohrbach, Anna
Cryptography and Security
Artificial Intelligence
Machine Learning
The expansion of text-to-image diffusion models has raised concerns about harmful outputs, from fabricated depictions of public figures to sexually explicit imagery. To mitigate such risks, prior work has proposed concept erasure methods that aim to sever unwanted concepts from the model via fine-tuning, yet it remains unclear whether these approaches truly remove all links to the harmful concept or merely conceal superficial connections. In this work, we reveal a critical vulnerability, the Erasure Evasion Backdoor (EEB): an adversary binds a backdoor trigger to a concept slated for removal, and this malicious link survives subsequent erasure. We show that both black-box and white-box adversaries can instantiate this threat. Across six state-of-the-art erasure methods, including robust ones that explicitly search for alternative representations of the target concept, EEB consistently exposes harmful content: up to 82% success against celebrity-identity unlearning, up to 94% for object erasure, and up to 16 times amplification of explicit-content exposure. While EEB uncovers a blind spot in current erasure methods, it also provides a diagnostic tool for stress-testing future concept erasure techniques.
title Erased but Not Forgotten: How Backdoors Compromise Concept Erasure
topic Cryptography and Security
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2504.21072