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Main Authors: Bhasin, Vedant, Yudin, Matthew, Stefanescu, Razvan, Izmailov, Rauf
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2501.11621
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author Bhasin, Vedant
Yudin, Matthew
Stefanescu, Razvan
Izmailov, Rauf
author_facet Bhasin, Vedant
Yudin, Matthew
Stefanescu, Razvan
Izmailov, Rauf
contents Trojan backdoors can be injected into large language models at various stages, including pretraining, fine-tuning, and in-context learning, posing a significant threat to the model's alignment. Due to the nature of causal language modeling, detecting these triggers is challenging given the vast search space. In this study, we propose a multistage framework for detecting Trojan triggers in large language models consisting of token filtration, trigger identification, and trigger verification. We discuss existing trigger identification methods and propose two variants of a black-box trigger inversion method that rely on output logits, utilizing beam search and greedy decoding respectively. We show that the verification stage is critical in the process and propose semantic-preserving prompts and special perturbations to differentiate between actual Trojan triggers and other adversarial strings that display similar characteristics. The evaluation of our approach on the TrojAI and RLHF poisoned model datasets demonstrates promising results.
format Preprint
id arxiv_https___arxiv_org_abs_2501_11621
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Trojan Detection Through Pattern Recognition for Large Language Models
Bhasin, Vedant
Yudin, Matthew
Stefanescu, Razvan
Izmailov, Rauf
Computation and Language
Machine Learning
68T10, 68T20
I.2; I.5
Trojan backdoors can be injected into large language models at various stages, including pretraining, fine-tuning, and in-context learning, posing a significant threat to the model's alignment. Due to the nature of causal language modeling, detecting these triggers is challenging given the vast search space. In this study, we propose a multistage framework for detecting Trojan triggers in large language models consisting of token filtration, trigger identification, and trigger verification. We discuss existing trigger identification methods and propose two variants of a black-box trigger inversion method that rely on output logits, utilizing beam search and greedy decoding respectively. We show that the verification stage is critical in the process and propose semantic-preserving prompts and special perturbations to differentiate between actual Trojan triggers and other adversarial strings that display similar characteristics. The evaluation of our approach on the TrojAI and RLHF poisoned model datasets demonstrates promising results.
title Trojan Detection Through Pattern Recognition for Large Language Models
topic Computation and Language
Machine Learning
68T10, 68T20
I.2; I.5
url https://arxiv.org/abs/2501.11621