Linux
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Posts
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Binary Hardening on Linux: What Canaries, NX, ASLR, RELRO, FORTIFY and CET Actually Stop
A tour of the compiler, linker and kernel mitigations inside a modern Linux binary, what each one prevents and does not prevent, and how to verify all of them with readelf, objdump and checksec.
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just-exit: Getting a Shell by Asking for a Syscall That Is Forbidden
A write-up of the pwnable challenge just-exit from DreamHack CTF Season 7, where every modern mitigation is on and the exploit is a single byte, because the seccomp filter answers a denied syscall with SIGSYS and the program's SIGSYS handler calls system.
