Pwn 9. Writing Shellcodes
SPbCTF Meeting (https://vk.com/spbctf)
Egor Zaitsev explains how to execute not just some library function, but truly arbitrary code: write shellcode that performs the necessary operations via syscalls.
Solve problems — https://pwn.spbctf.ru
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0:00 Why shellcode is used
4:44 Demo environment. Executing raw bytes as instructions
15:58 Collections of ready-made shellcode
20:56 Writing your own shellcode. System calls
25:21 Compiling shellcode. NASM
40:56 Passing data to syscall. PUSH on the stack
54:17 Shellcoding with restrictions: no null bytes allowed
1:02:19 Shellcoding with restrictions: limited space
1:09:39 Addressing data inside shellcode using CALL