Detecting speculative leaks with compositional semantics

Fuente: arXiv
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Autores principales: Fabian, Xaver, Guarnieri, Marco, Köpf, Boris, Morales, Jose F., Patrignani, Marco, Reineke, Jan, Sanchez, Andres
Formato: Preprint
Publicado: 2026
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author Fabian, Xaver
Guarnieri, Marco
Köpf, Boris
Morales, Jose F.
Patrignani, Marco
Reineke, Jan
Sanchez, Andres
author_facet Fabian, Xaver
Guarnieri, Marco
Köpf, Boris
Morales, Jose F.
Patrignani, Marco
Reineke, Jan
Sanchez, Andres
contents Speculative execution enhances processor performance by predicting intermediate results and executing instructions based on these predictions. However, incorrect predictions can lead to security vulnerabilities, as speculative instructions leave traces in microarchitectural components that attackers can exploit. This is demonstrated by the family of Spectre attacks. Unfortunately, existing countermeasures to these attacks lack a formal security characterization, making it difficult to verify their effectiveness. In this paper, we propose a novel framework for detecting information flows introduced by speculative execution and reasoning about software defenses. The theoretical foundation of our approach is speculative non-interference (SNI), a novel semantic notion of security against speculative execution attacks. SNI relates information leakage observed under a standard non-speculative semantics to leakage arising under semantics that explicitly model speculative execution. To capture their combined effects, we extend our framework with a mechanism to safely compose multiple speculative semantics, each focussing on a single aspect of speculation. This allows us to analyze the complex interactions and resulting leaks that can arise when multiple speculative mechanisms operate together. On the practical side, we develop Spectector, a symbolic analysis tool that uses our compositional framework and leverages SMT solvers to detect vulnerabilities and verify program security with respect to multiple speculation mechanisms. We demonstrate the effectiveness of Spectector through evaluations on standard security benchmarks and new vulnerability scenarios.
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id arxiv_https___arxiv_org_abs_2603_29800
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Detecting speculative leaks with compositional semantics
Fabian, Xaver
Guarnieri, Marco
Köpf, Boris
Morales, Jose F.
Patrignani, Marco
Reineke, Jan
Sanchez, Andres
Cryptography and Security
Speculative execution enhances processor performance by predicting intermediate results and executing instructions based on these predictions. However, incorrect predictions can lead to security vulnerabilities, as speculative instructions leave traces in microarchitectural components that attackers can exploit. This is demonstrated by the family of Spectre attacks. Unfortunately, existing countermeasures to these attacks lack a formal security characterization, making it difficult to verify their effectiveness. In this paper, we propose a novel framework for detecting information flows introduced by speculative execution and reasoning about software defenses. The theoretical foundation of our approach is speculative non-interference (SNI), a novel semantic notion of security against speculative execution attacks. SNI relates information leakage observed under a standard non-speculative semantics to leakage arising under semantics that explicitly model speculative execution. To capture their combined effects, we extend our framework with a mechanism to safely compose multiple speculative semantics, each focussing on a single aspect of speculation. This allows us to analyze the complex interactions and resulting leaks that can arise when multiple speculative mechanisms operate together. On the practical side, we develop Spectector, a symbolic analysis tool that uses our compositional framework and leverages SMT solvers to detect vulnerabilities and verify program security with respect to multiple speculation mechanisms. We demonstrate the effectiveness of Spectector through evaluations on standard security benchmarks and new vulnerability scenarios.
title Detecting speculative leaks with compositional semantics
topic Cryptography and Security
url https://arxiv.org/abs/2603.29800