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Buffer overflow 111/27/2023 ![]() The program first reads in input from a file called badfile, and ultimately passes this input to another buffer in the function bof(). ![]() Your main objective throughout parts of this lab will be to exploit this vulnerability and get a shell with root privileges. The following program has a buffer-overflow vulnerability. The following command can be used to link /bin/sh to /bin/zsh: We have installed a shell program called zsh in our Ubuntu 20.04 VM. (In later tasks, we will show that with a little more effort, the countermeasure in /bin/dash can be easily defeated!) Therefore, we will link /bin/sh to another shell that does not have this countermeasure. The countermeasure in /bin/dash makes our attack more difficult. The victim of many of our attacks in this lab is a set-uid program, and our attack relies on running /bin/sh They will immediately change the effective user ID to the process’s real user ID,Įffectively dropping any elevated privileges. The dash and bash shells have implemented a security countermeasure that prevents itself from being executed in a set-uid process.īasically, if they detect that they are executed in a set-uid process, In the recent versions of Ubuntu OS, the /bin/sh symbolic link points $ sudo sysctl -w kernel.randomize_va_space =0 A related video lecture (Udemy course) recorded by Kevin Du.The Definitive Guide to Linux System Calls.Code related to this lab can be found in 03_buffer_overflow/ of our class’s GitHub repository.(Specifically, the Set-UID version.) Resources ![]() This lab is an adaptation of the SEED Labs “Buffer Overflow Attack Lab”. Non-executable stack countermeasure, is covered in a separate lab.
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