Zero-delay Lightweight Defenses against Website Fingerprinting

Authors: 

Jiajun Gong and Tao Wang, Hong Kong University of Science and Technology

Abstract: 

Website Fingerprinting (WF) attacks threaten user privacy on anonymity networks because they can be used by network surveillants to identify the webpage being visited by extracting features from network traffic. A number of defenses have been put forward to mitigate the threat of WF, but they are flawed: some have been defeated by stronger WF attacks, some are too expensive in overhead, while others are impractical to deploy.

In this work, we propose two novel zero-delay lightweight defenses, FRONT and GLUE. We find that WF attacks rely on the feature-rich trace front, so FRONT focuses on obfuscating the trace front with dummy packets. It also randomizes the number and distribution of dummy packets for trace-to-trace randomness to impede the attacker’s learning process. GLUE adds dummy packets between separate traces so that they appear to the attacker as a long consecutive trace, rendering the attacker unable to find their start or end points, let alone classify them. Our experiments show that with 33% data overhead, FRONT outperforms the best known lightweight defense, WTF-PAD, which has a similar data overhead. With around 22%–44% data overhead, GLUE can lower the accuracy and precision of the best WF attacks to a degree comparable with the best heavyweight defenses. Both defenses have no latency overhead.

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BibTeX
@inproceedings {247654,
title = {Zero-delay Lightweight Defenses against Website Fingerprinting},
booktitle = {29th {USENIX} Security Symposium ({USENIX} Security 20)},
year = {2020},
address = {Boston, MA},
url = {https://www.usenix.org/conference/usenixsecurity20/presentation/gong},
publisher = {{USENIX} Association},
month = aug,
}