View profile for Naman Devnani

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X.509 Certificate Smuggling: Executables Delivered via TLS Certificates A new proof-of-concept highlights a novel technique for delivering executable payloads through X.509 TLS certificates. This approach avoids traditional delivery mechanisms entirely - no file downloads, no direct payload URLs. How it works: -> A binary executable is converted to a HEX string and embedded into a certificate extension (OID field). -> During an HTTPS connection, the client extracts the HEX, decodes it, and executes it - potentially all in memory. -> The certificate appears legitimate to most inspection tools, and no executable touches disk unless explicitly written. Why this matters for red teams: -> No file download means NGFWs and traditional proxies do not see a PE file being transferred. -> The TLS handshake is used as the delivery channel, which blends into normal encrypted traffic. -> The server hosting the certificate can appear fully legitimate, making traffic analysis difficult for defenders. -> The payload can be executed directly from memory, reducing forensic artifacts. Detection considerations: -> The payload is still a PE file, with the MZ header intact. -> Open-source detection tools like Suricata do not typically inspect OID fields in certificates, leaving a visibility gap. -> The HEX payload can be further obfuscated or modified to avoid static detection. This technique is a powerful example of abusing non-traditional channels for payload delivery. It underscores the need for deeper inspection of TLS metadata and certificate contents in both network and endpoint monitoring pipelines. PoC: https://lnkd.in/dK4nDMmU #infosec #cybersecurity #redteam #blueteam #malware

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