# Shortcuts Everywhere and Nowhere: Exploring Multi-Trigger Backdoor Attacks

arXiv: https://arxiv.org/abs/2401.15295 · HTML: https://mlsanity.com/paper/2401.15295/

## Key facts

- Cited by 19 papers in the map (data through 14 Oct 2026).
- Builds on 33 of its 49 references that are in the map.
- First posted on arXiv 27 Jan 2024.

## Builds on (most cited first, 30 of 33)

- [Deep Residual Learning for Image Recognition](https://mlsanity.com/paper/1512.03385/) (2015)
- [BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding](https://mlsanity.com/paper/1810.04805/) (2018)
- [Language Models are Few-Shot Learners](https://mlsanity.com/paper/2005.14165/) (2020)
- [An Image is Worth 16x16 Words: Transformers for Image Recognition at Scale](https://mlsanity.com/paper/2010.11929/) (2020)
- [MobileNets: Efficient Convolutional Neural Networks for Mobile Vision Applications](https://mlsanity.com/paper/1704.04861/) (2017)
- [BadNets: Identifying Vulnerabilities in the Machine Learning Model Supply Chain](https://mlsanity.com/paper/1708.06733/) (2017)
- [Targeted Backdoor Attacks on Deep Learning Systems Using Data Poisoning](https://mlsanity.com/paper/1712.05526/) (2017)
- [Fine-Pruning: Defending Against Backdooring Attacks on Deep Neural Networks](https://mlsanity.com/paper/1805.12185/) (2018)
- [Listen, Attend and Spell](https://mlsanity.com/paper/1508.01211/) (2015)
- [Spectral Signatures in Backdoor Attacks](https://mlsanity.com/paper/1811.00636/) (2018)
- [STRIP: A Defence Against Trojan Attacks on Deep Neural Networks](https://mlsanity.com/paper/1902.06531/) (2019)
- [Detecting Backdoor Attacks on Deep Neural Networks by Activation Clustering](https://mlsanity.com/paper/1811.03728/) (2018)
- [Backdoor Learning: A Survey](https://mlsanity.com/paper/2007.08745/) (2020)
- [Invisible Backdoor Attack with Sample-Specific Triggers](https://mlsanity.com/paper/2012.03816/) (2020)
- [Reflection Backdoor: A Natural Backdoor Attack on Deep Neural Networks](https://mlsanity.com/paper/2007.02343/) (2020)
- [Neural Attention Distillation: Erasing Backdoor Triggers from Deep Neural Networks](https://mlsanity.com/paper/2101.05930/) (2021)
- [Input-Aware Dynamic Backdoor Attack](https://mlsanity.com/paper/2010.08138/) (2020)
- [Anti-Backdoor Learning: Training Clean Models on Poisoned Data](https://mlsanity.com/paper/2110.11571/) (2021)
- [A new Backdoor Attack in CNNs by training set corruption without label poisoning](https://mlsanity.com/paper/1902.11237/) (2019)
- [Adversarial Neuron Pruning Purifies Backdoored Deep Models](https://mlsanity.com/paper/2110.14430/) (2021)
- [Detecting AI Trojans Using Meta Neural Analysis](https://mlsanity.com/paper/1910.03137/) (2019)
- [Rethinking the Backdoor Attacks' Triggers: A Frequency Perspective](https://mlsanity.com/paper/2104.03413/) (2021)
- [Backdoor Defense via Decoupling the Training Process](https://mlsanity.com/paper/2202.03423/) (2022)
- [TABOR: A Highly Accurate Approach to Inspecting and Restoring Trojan Backdoors in AI Systems](https://mlsanity.com/paper/1908.01763/) (2019)
- [Deep Feature Space Trojan Attack of Neural Networks by Controlled Detoxification](https://mlsanity.com/paper/2012.11212/) (2020)
- [Data-free Backdoor Removal based on Channel Lipschitzness](https://mlsanity.com/paper/2208.03111/) (2022)
- [Rethinking the Trigger of Backdoor Attack](https://mlsanity.com/paper/2004.04692/) (2020)
- [Reconstructive Neuron Pruning for Backdoor Defense](https://mlsanity.com/paper/2305.14876/) (2023)
- [MM-BD: Post-Training Detection of Backdoor Attacks with Arbitrary Backdoor Pattern Types Using a Maximum Margin Statistic](https://mlsanity.com/paper/2205.06900/) (2022)
- [Distilling Cognitive Backdoor Patterns within an Image](https://mlsanity.com/paper/2301.10908/) (2023)

## Built on by (most cited first, 19 of 19)

- [Safety at Scale: A Comprehensive Survey of Large Model and Agent Safety](https://mlsanity.com/paper/2502.05206/) (2025)
- [CROW: Eliminating Backdoors from Large Language Models via Internal Consistency Regularization](https://mlsanity.com/paper/2411.12768/) (2024)
- [Purifying Generative LLMs from Backdoors without Prior Knowledge or Clean Reference](https://mlsanity.com/paper/2603.13461/) (2026)
- [P2P: A Poison-to-Poison Remedy for Reliable Backdoor Defense in LLMs](https://mlsanity.com/paper/2510.04503/) (2025)
- [Pay Attention to the Triggers: Constructing Backdoors That Survive Distillation](https://mlsanity.com/paper/2510.18541/) (2025)
- [Multi-Trigger Poisoning Amplifies Backdoor Vulnerabilities in LLMs](https://mlsanity.com/paper/2507.11112/) (2025)
- [BADTV: Unveiling Backdoor Threats in Third-Party Task Vectors](https://mlsanity.com/paper/2501.02373/) (2025)
- [Non-Cooperative Backdoor Attacks in Federated Learning: A New Threat Landscape](https://mlsanity.com/paper/2407.07917/) (2024)
- [DISTIL: Data-Free Inversion of Suspicious Trojan Inputs via Latent Diffusion](https://mlsanity.com/paper/2507.22813/) (2025)
- [Kill it with FIRE: On Leveraging Latent Space Directions for Runtime Backdoor Mitigation in Deep Neural Networks](https://mlsanity.com/paper/2602.10780/) (2026)
- [Defending against Backdoor Attacks via Module Switching](https://mlsanity.com/paper/2504.05902/) (2025)
- [Proactive Disentangled Modeling of Trigger-Object Pairings for Backdoor Defense](https://mlsanity.com/paper/2508.01932/) (2025)
- [Backdoor Samples Detection Based on Perturbation Discrepancy Consistency in Pre-trained Language Models](https://mlsanity.com/paper/2509.05318/) (2025)
- [Localizing Malicious Outputs from CodeLLM](https://mlsanity.com/paper/2509.17070/) (2025)
- [Microsaccade-Inspired Probing: Positional Encoding Perturbations Reveal LLM Misbehaviours](https://mlsanity.com/paper/2510.01288/) (2025)
- [Cordyceps: Covert Control Attacks on LLMs via Data Poisoning](https://mlsanity.com/paper/2605.26595/) (2026)
- [LoRAScan: Detecting Backdoor Prompts in Low-Rank Adapters for Large Language Models via Down-Projection Activation Spikes](https://mlsanity.com/paper/2608.06795/) (2026)
- [Backdoor Containment via Expert Quarantine and Shutdown in LLMs](https://mlsanity.com/paper/2610.00663/) (2026)
- [Backdoor Purification for LoRA-Tuned LLMs via Null-Space Projection](https://mlsanity.com/paper/2610.00685/) (2026)

## Abstract (arXiv)

Backdoor attacks have become a significant threat to the pre-training and deployment of deep neural networks (DNNs). Although numerous methods for detecting and mitigating backdoor attacks have been proposed, most rely on identifying and eliminating the ``shortcut" created by the backdoor, which links a specific source class to a target class. However, these approaches can be easily circumvented by designing multiple backdoor triggers that create shortcuts everywhere and therefore nowhere specific. In this study, we explore the concept of Multi-Trigger Backdoor Attacks (MTBAs), where multiple adversaries leverage different types of triggers to poison the same dataset. By proposing and investigating three types of multi-trigger attacks including textitparallel, textitsequential, and textithybrid attacks, we demonstrate that 1) multiple triggers can coexist, overwrite, or cross-activate one another, and 2) MTBAs easily break the prevalent shortcut assumption underlying most existing backdoor detection/removal methods, rendering them ineffective. Given the security risk posed by MTBAs, we have created a multi-trigger backdoor poisoning dataset to facilitate future research on detecting and mitigating these attacks, and we also discuss potential defense strategies against MTBAs. Our code is available at https://github.com/bboylyg/Multi-Trigger-Backdoor-Attacks.