Stefanos Koffas

According to our database, Stefanos Koffas authored at least 30 papers between 2022 and 2026.

Collaborative distances:

• Dijkstra number of four.
• Erdős number of four.

2026

Backdoor Attacks on Decentralised Post-Training.

Oguzhan Ersoy, Nikolay Blagoev, Jona te Lintelo, Stefanos Koffas, Marina Krcek, Stjepan Picek

CoRR, April, 2026

Removing the Trigger, Not the Backdoor: Alternative Triggers and Latent Backdoors.

Gorka Abad, Ermes Franch, Stefanos Koffas, Stjepan Picek

CoRR, March, 2026

Let's focus: Focused backdoor attack against federated transfer learning.

Marco Arazzi, Stefanos Koffas, Antonino Nocera, Stjepan Picek

Neurocomputing, 2026

CatBack: Universal Backdoor Attacks on Tabular Data via Categorical Encoding.

Behrad Tajalli, Stefanos Koffas, Stjepan Picek

Proceedings of the 33rd Annual Network and Distributed System Security Symposium, 2026

Dr. Jekyll and Mr. Hyde: Two Faces of LLMs.

Matteo Gioele Collu, Tom Janssen-Groesbeek, Stefanos Koffas, Mauro Conti, Stjepan Picek

Proceedings of the Joint National Conference on Cybersecurity (ITASEC & SERICS 2026), 2026

2025

SoK: The Last Line of Defense: On Backdoor Defense Evaluation.

Gorka Abad, Marina Krcek, Stefanos Koffas, Behrad Tajalli, Marco Arazzi, Roberto Riaño, Xiaoyun Xu, Zhuoran Liu, Antonino Nocera, Stjepan Picek

CoRR, November, 2025

L² · M = C² Large Language Models Are Covert Channels.

Simen Gaure, Stefanos Koffas, Stjepan Picek, Sondre Rønjom

Proceedings of the 2025 IEEE International Conference on Acoustics, 2025

Backdoor Attacks on Transformers for Tabular Data: An Empirical Study.

Bart Pleiter, Behrad Tajalli, Stefanos Koffas, Gorka Abad, Jing Xu, Martha A. Larson, Stjepan Picek

Proceedings of the Computer Security. ESORICS 2025 International Workshops, 2025

Towards Backdoor Stealthiness in Model Parameter Space.

Xiaoyun Xu, Zhuoran Liu, Stefanos Koffas, Stjepan Picek

Proceedings of the 2025 ACM SIGSAC Conference on Computer and Communications Security, 2025

2024

Toward Stealthy Backdoor Attacks Against Speech Recognition via Elements of Sound.

Hanbo Cai, Pengcheng Zhang, Hai Dong, Yan Xiao, Stefanos Koffas, Yiming Li

IEEE Trans. Inf. Forensics Secur., 2024

Unveiling the Threat: Investigating Distributed and Centralized Backdoor Attacks in Federated Graph Neural Networks.

Jing Xu, Stefanos Koffas, Stjepan Picek

DTRAP, 2024

L² · M = C² Large Language Models as Covert Channels... a Systematic Analysis.

Simen Gaure, Stefanos Koffas, Stjepan Picek, Sondre Rønjom

CoRR, 2024

The SpongeNet Attack: Sponge Weight Poisoning of Deep Neural Networks.

Jona te Lintelo, Stefanos Koffas, Stjepan Picek

CoRR, 2024

Beyond PhantomSponges: Enhancing Sponge Attack on Object Detection Models.

Coen Schoof, Stefanos Koffas, Mauro Conti, Stjepan Picek

Proceedings of the 2024 ACM Workshop on Wireless Security and Machine Learning, 2024

Backdoors on Manifold Learning.

Christina Kreza, Stefanos Koffas, Behrad Tajalli, Mauro Conti, Stjepan Picek

Proceedings of the 2024 ACM Workshop on Wireless Security and Machine Learning, 2024

BAN: Detecting Backdoors Activated by Adversarial Neuron Noise.

Xiaoyun Xu, Zhuoran Liu, Stefanos Koffas, Shujian Yu, Stjepan Picek

Proceedings of the Advances in Neural Information Processing Systems 37: Annual Conference on Neural Information Processing Systems 2024, 2024

ELMs Under Siege: A Study on Backdoor Attacks on Extreme Learning Machines.

Behrad Tajalli, Stefanos Koffas, Gorka Abad, Stjepan Picek

Proceedings of the 2024 Workshop on Artificial Intelligence and Security, 2024

EmoBack: Backdoor Attacks Against Speaker Identification Using Emotional Prosody.

Coen Schoof, Stefanos Koffas, Mauro Conti, Stjepan Picek

Proceedings of the 2024 Workshop on Artificial Intelligence and Security, 2024

2023

Backdoor Pony: Evaluating backdoor attacks and defenses in different domains.

Arthur Mercier, Nikita Smolin, Oliver Sihlovec, Stefanos Koffas, Stjepan Picek

SoftwareX, May, 2023

Tabdoor: Backdoor Vulnerabilities in Transformer-based Neural Networks for Tabular Data.

Bart Pleiter, Behrad Tajalli, Stefanos Koffas, Gorka Abad, Jing Xu, Martha A. Larson, Stjepan Picek

CoRR, 2023

Invisible Threats: Backdoor Attack in OCR Systems.

Mauro Conti, Nicola Farronato, Stefanos Koffas, Luca Pajola, Stjepan Picek

CoRR, 2023

BlindSage: Label Inference Attacks against Node-level Vertical Federated Graph Neural Networks.

Marco Arazzi, Mauro Conti, Stefanos Koffas, Marina Krcek, Antonino Nocera, Stjepan Picek, Jing Xu

CoRR, 2023

Towards Stealthy Backdoor Attacks against Speech Recognition via Elements of Sound.

Hanbo Cai, Pengcheng Zhang, Hai Dong, Yan Xiao, Stefanos Koffas, Yiming Li

CoRR, 2023

A Systematic Evaluation of Backdoor Trigger Characteristics in Image Classification.

Gorka Abad, Jing Xu, Stefanos Koffas, Behrad Tajalli, Stjepan Picek

CoRR, 2023

Going in Style: Audio Backdoors Through Stylistic Transformations.

Stefanos Koffas, Luca Pajola, Stjepan Picek, Mauro Conti

Proceedings of the IEEE International Conference on Acoustics, 2023

Watermarking Graph Neural Networks based on Backdoor Attacks.

Jing Xu, Stefanos Koffas, Oguzhan Ersoy, Stjepan Picek

Proceedings of the 8th IEEE European Symposium on Security and Privacy, 2023

2022

Can You Hear It?: Backdoor Attacks via Ultrasonic Triggers.

Stefanos Koffas, Jing Xu, Mauro Conti, Stjepan Picek

Proceedings of the WiseML@WiSec 2022: Proceedings of the 2022 ACM Workshop on Wireless Security and Machine Learning, 2022

Dynamic Backdoors with Global Average Pooling.

Stefanos Koffas, Stjepan Picek, Mauro Conti

Proceedings of the 4th IEEE International Conference on Artificial Intelligence Circuits and Systems, 2022

More is Better (Mostly): On the Backdoor Attacks in Federated Graph Neural Networks.

Jing Xu, Rui Wang, Stefanos Koffas, Kaitai Liang, Stjepan Picek

Proceedings of the Annual Computer Security Applications Conference, 2022

On the Effect of Clock Frequency on Voltage and Electromagnetic Fault Injection.

Stefanos Koffas, Praveen Kumar Vadnala

Proceedings of the Applied Cryptography and Network Security Workshops, 2022