Investigation of Web-based Flush+Reload Attack for RSA Key Extraction on Native Targets

• Felipe S. Simões UFF
• Lucila M. S. Bento UERJ
• Raphael C. S. Machado UFF

DOI: https://doi.org/10.5753/sbseg.2025.10400

Abstract

WebAssembly enables the execution of complex applications in the browser, raising the question about the potential adaptation of sophisticated native attacks, such as Flush+Reload—a high-resolution cache side-channel attack. This work experimentally investigates the feasibility of executing Flush+Reload from the browser against an external native GPG process to extract RSA keys, comparing this approach with native implementations. Results indicate a clear contrast: while native versions achieved partial success (nearly 50% accuracy), the web-based approach proved ineffective (accuracy below 4%), limited by inherent challenges in timing resolution and noise within the browser environment. These findings indicate a fundamental difference in the current exploitability of this attack vector against external targets when comparing web and native environments.

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