Breaking Legacy Routers: 5 Zero-Days via Reversing and Hardware Hacking

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Presented at Recon 2025 by

Danilo Erazo

End-of-life doesn't mean end-of-risk. In this fun and eye-opening talk, we’ll dive into five never-before-seen zero-day vulnerabilities uncovered in widely deployed legacy routers still active in thousands of networks, especially across South America. Using a mix of hardware hacking and binary reversing, you'll see how four of the zero-days were discovered directly through the board using UART and chip-level tactics, while a fifth was revealed by digging into obscure ARCompact binaries. From discovering Wi-Fi credentials like a boss, to navigating lateral movement between dual SoCs and overcoming tricky UART communication issues, this session is packed with real-world reversing, clever hardware techniques, and lessons for anyone working with embedded devices. No patches are available, as these routers have reached end-of-life and the vendor will not issue security updates.