9: Overwriting Global Offset Table (GOT) Entries with printf() - Intro to Binary Exploitation (Pwn)

9th video from the "Practical Buffer Overflow Exploitation" course covering the basics of Binary Exploitation. NX and stack canaries are enabled this time, so we'll use a printf() format string vulnerability overwrite an entry from the Global Offset Table (GOT) with system() function from the Lib-C library. We'll use checksec, ghidra, pwndbg and create a manual printf() format write payload as well as using the pwntools FmtStr functionality! Write-ups/tutorials aimed at beginners - Hope you enjoy 🙂 #BinaryExploitation #BufferOverflow #BinExp #RE #Pwn #PwnTools

Find the binary files, source code and scripts to go with the series @ https://github.com/Crypto-Cat/CTF/tree/main/pwn/binary_exploitation_101

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↢Binary Exploitation / Reverse Engineering↣
Pwn.College: https://pwn.college
How2Heap: https://github.com/shellphish/how2heap
NightMare: https://guyinatuxedo.github.io
Ir0nstone: https://ir0nstone.gitbook.io/notes/types/stack
PinkDraconian: https://www.youtube.com/playlist?list=PLeSXUd883dhjmKkVXSRgI1nJEZUDzgLf_
More: https://github.com/Crypto-Cat/CTF#readme

↢Video-Specific Resources↣
https://systemoverlord.com/2017/03/19/got-and-plt-for-pwning.html
https://ir0nstone.gitbook.io/notes/types/stack/aslr/plt_and_got
https://vickieli.dev/binary%20exploitation/format-string-vulnerabilities
https://codearcana.com/posts/2013/05/02/introduction-to-format-string-exploits.html
https://axcheron.github.io/exploit-101-format-strings
https://docs.pwntools.com/en/stable/fmtstr.html

↢Resources↣
Ghidra: https://ghidra-sre.org/CheatSheet.html
PwnTools: https://github.com/Gallopsled/pwntools-tutorial
CyberChef: https://gchq.github.io/CyberChef
HackTricks: https://book.hacktricks.xyz/exploiting/linux-exploiting-basic-esp
GTFOBins: https://gtfobins.github.io
Decompile Code: https://www.decompiler.com
Run Code: https://tio.run

↢Chapters↣
Start: 0:00
Basic File Checks: 0:32
Review Source Code: 2:10
Disassemble with Ghidra: 3:15
Outline Attack (GOT Overwrite): 4:60
GOT vs PLT vs GOT.PLT vs PLT.GOT: 6:07
Fuzz Printf Format Vuln: 8:55
Printf Format Write (%n) Explained: 9:36
Finding Correct Offset for Write: 13:00
How to Build a Manual Payload: 13:55
Manual Printf Write Exploit (%n): 18:08
PwnTools Script (FmtStr Auto): 22:07
End: 26:25