Byte by Byte: Unmasking Browser Fingerprinting at the Function Level Using V8 Bytecode Transformers

Fuente: arXiv
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Hauptverfasser: Bahrami, Pouneh Nikkhah, Cutler, Dylan, Bilogrevic, Igor
Format: Preprint
Veröffentlicht: 2025
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author Bahrami, Pouneh Nikkhah
Cutler, Dylan
Bilogrevic, Igor
author_facet Bahrami, Pouneh Nikkhah
Cutler, Dylan
Bilogrevic, Igor
contents Browser fingerprinting enables persistent cross-site user tracking via subtle techniques that often evade conventional defenses or cause website breakage when script-level blocking countermeasures are applied. Addressing these challenges requires detection methods offering both function-level precision to minimize breakage and inherent robustness against code obfuscation and URL manipulation. We introduce ByteDefender, the first system leveraging V8 engine bytecode to detect fingerprinting operations specifically at the JavaScript function level. A Transformer-based classifier, trained offline on bytecode sequences, accurately identifies functions exhibiting fingerprinting behavior. We develop and evaluate light-weight signatures derived from this model to enable low-overhead, on-device matching against function bytecode during compilation but prior to execution, which only adds a 4% (average) latency to the page load time. This mechanism facilitates targeted, real-time prevention of fingerprinting function execution, thereby preserving legitimate script functionality. Operating directly on bytecode ensures inherent resilience against common code obfuscation and URL-based evasion. Our evaluation on the top 100k websites demonstrates high detection accuracy at both function- and script-level, with substantial improvements over state-of-the-art AST-based methods, particularly in robustness against obfuscation. ByteDefender offers a practical framework for effective, precise, and robust fingerprinting mitigation.
format Preprint
id arxiv_https___arxiv_org_abs_2509_09950
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Byte by Byte: Unmasking Browser Fingerprinting at the Function Level Using V8 Bytecode Transformers
Bahrami, Pouneh Nikkhah
Cutler, Dylan
Bilogrevic, Igor
Cryptography and Security
Browser fingerprinting enables persistent cross-site user tracking via subtle techniques that often evade conventional defenses or cause website breakage when script-level blocking countermeasures are applied. Addressing these challenges requires detection methods offering both function-level precision to minimize breakage and inherent robustness against code obfuscation and URL manipulation. We introduce ByteDefender, the first system leveraging V8 engine bytecode to detect fingerprinting operations specifically at the JavaScript function level. A Transformer-based classifier, trained offline on bytecode sequences, accurately identifies functions exhibiting fingerprinting behavior. We develop and evaluate light-weight signatures derived from this model to enable low-overhead, on-device matching against function bytecode during compilation but prior to execution, which only adds a 4% (average) latency to the page load time. This mechanism facilitates targeted, real-time prevention of fingerprinting function execution, thereby preserving legitimate script functionality. Operating directly on bytecode ensures inherent resilience against common code obfuscation and URL-based evasion. Our evaluation on the top 100k websites demonstrates high detection accuracy at both function- and script-level, with substantial improvements over state-of-the-art AST-based methods, particularly in robustness against obfuscation. ByteDefender offers a practical framework for effective, precise, and robust fingerprinting mitigation.
title Byte by Byte: Unmasking Browser Fingerprinting at the Function Level Using V8 Bytecode Transformers
topic Cryptography and Security
url https://arxiv.org/abs/2509.09950