驱动开发：内核枚举ShadowSSDT基址

发表于 2023-04-26 更新于 2023-07-04 分类于《Windows 内核安全编程技术实践》

在笔者上一篇文章`《驱动开发：内核枚举SSDT表基址》`实现了针对`SSDT`表的枚举功能，本章继续实现对`SSSDT`表的枚举，`ShadowSSDT`中文名`影子系统服务描述表`，SSSDT其主要的作用是管理系统中的图形化界面，其`Win32`子系统的内核实现是`Win32k.sys`驱动，属于GUI线程的一部分，其自身没有导出表，枚举`SSSDT`表其与`SSDT`原理基本一致。

在笔者上一篇文章《驱动开发：内核枚举SSDT表基址》实现了针对SSDT表的枚举功能，本章继续实现对SSSDT表的枚举，ShadowSSDT中文名影子系统服务描述表，SSSDT其主要的作用是管理系统中的图形化界面，其Win32子系统的内核实现是Win32k.sys驱动，属于GUI线程的一部分，其自身没有导出表，枚举SSSDT表其与SSDT原理基本一致。

如下是闭源ARK工具的枚举效果:

首先需要找到SSSDT表的位置，通过《Win10内核枚举SSDT表基址》文章中的分析可知，SSSDT就在SSDT的下面，只需要枚举4c8d1dde1e3a00特征即可，如果你找不到上一篇具体分析流程了，那么多半你是看到了转载文章。

先实现第一个功能，得到SSSDT表的基地址以及SSDT函数个数，完整代码如下所示。

#include <ntifs.h>
#pragma intrinsic(__readmsr)

typedef struct _SYSTEM_SERVICE_TABLE
{
	PVOID          ServiceTableBase;
	PVOID          ServiceCounterTableBase;
	ULONGLONG      NumberOfServices;
	PVOID          ParamTableBase;
} SYSTEM_SERVICE_TABLE, *PSYSTEM_SERVICE_TABLE;

PSYSTEM_SERVICE_TABLE KeServiceDescriptorTableShadow = 0;
ULONG64 ul64W32pServiceTable = 0;

// 获取 KeServiceDescriptorTableShadow 首地址
ULONGLONG GetKeServiceDescriptorTableShadow()
{
	// 设置起始位置
	PUCHAR StartSearchAddress = (PUCHAR)__readmsr(0xC0000082) - 0x1808FE;

	// 设置结束位置
	PUCHAR EndSearchAddress = StartSearchAddress + 0x8192;
	// DbgPrint("扫描起始地址: %p --> 扫描结束地址: %p \n", StartSearchAddress, EndSearchAddress);

	PUCHAR ByteCode = NULL;

	UCHAR OpCodeA = 0, OpCodeB = 0, OpCodeC = 0;
	ULONGLONG addr = 0;
	ULONG templong = 0;

	for (ByteCode = StartSearchAddress; ByteCode < EndSearchAddress; ByteCode++)
	{
		// 使用MmIsAddressValid()函数检查地址是否有页面错误
		if (MmIsAddressValid(ByteCode) && MmIsAddressValid(ByteCode + 1) && MmIsAddressValid(ByteCode + 2))
		{
			OpCodeA = *ByteCode;
			OpCodeB = *(ByteCode + 1);
			OpCodeC = *(ByteCode + 2);

			// 对比特征值 寻找 nt!KeServiceDescriptorTable 函数地址
			/*
			lyshark.com kd> u KiSystemServiceRepeat
				nt!KiSystemServiceRepeat:
				fffff802`7c1d2b94 4c8d15e59c3b00  lea     r10,[nt!KeServiceDescriptorTable (fffff802`7c58c880)]
				fffff802`7c1d2b9b 4c8d1dde1e3a00  lea     r11,[nt!KeServiceDescriptorTableShadow (fffff802`7c574a80)]
				fffff802`7c1d2ba2 f7437880000000  test    dword ptr [rbx+78h],80h
				fffff802`7c1d2ba9 7413            je      nt!KiSystemServiceRepeat+0x2a (fffff802`7c1d2bbe)
				fffff802`7c1d2bab f7437800002000  test    dword ptr [rbx+78h],200000h
				fffff802`7c1d2bb2 7407            je      nt!KiSystemServiceRepeat+0x27 (fffff802`7c1d2bbb)
				fffff802`7c1d2bb4 4c8d1d051f3a00  lea     r11,[nt!KeServiceDescriptorTableFilter (fffff802`7c574ac0)]
				fffff802`7c1d2bbb 4d8bd3          mov     r10,r11
			*/
			if (OpCodeA == 0x4c && OpCodeB == 0x8d && OpCodeC == 0x1d)
			{
				// 获取高位地址fffff802
				memcpy(&templong, ByteCode + 3, 4);

				// 与低位64da4880地址相加得到完整地址
				addr = (ULONGLONG)templong + (ULONGLONG)ByteCode + 7;
				return addr;
			}
		}
	}
	return  0;
}

// 得到SSSDT个数
ULONGLONG GetSSSDTCount()
{
	PSYSTEM_SERVICE_TABLE pWin32k;
	ULONGLONG W32pServiceTable;

	pWin32k = (PSYSTEM_SERVICE_TABLE)((ULONG64)KeServiceDescriptorTableShadow + sizeof(SYSTEM_SERVICE_TABLE));
	W32pServiceTable = (ULONGLONG)(pWin32k->ServiceTableBase);
	// DbgPrint("Count => %d \n", pWin32k->NumberOfServices);

	return pWin32k->NumberOfServices;
}

VOID UnDriver(PDRIVER_OBJECT driver)
{
	DbgPrint(("驱动程序卸载成功! \n"));
}

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
	DbgPrint("hello lyshark.com \n");

	KeServiceDescriptorTableShadow = (PSYSTEM_SERVICE_TABLE)GetKeServiceDescriptorTableShadow();

	DbgPrint("[LyShark] SSSDT基地址 = 0x%p \n", KeServiceDescriptorTableShadow);

	ULONGLONG count = GetSSSDTCount();

	DbgPrint("[LyShark] SSSDT个数 = %d \n", count);

	DriverObject->DriverUnload = UnDriver;
	return STATUS_SUCCESS;
}

这段代码运行后即可得到SSSDT表基地址，以及该表中函数个数。

在此基础之上增加枚举计算过程即可，完整源代码如下所示。

SSSDT 函数起始index是0x1000，但W32pServiceTable是从基址开始记录的，这个误差则需要(index-0x1000)来得到，至于+4则是下一个元素与上一个元素的偏移。

计算公式：

W32pServiceTable + 4 * (index-0x1000)

#include <ntifs.h>
#pragma intrinsic(__readmsr)

typedef struct _SYSTEM_SERVICE_TABLE
{
	PVOID          ServiceTableBase;
	PVOID          ServiceCounterTableBase;
	ULONGLONG      NumberOfServices;
	PVOID          ParamTableBase;
} SYSTEM_SERVICE_TABLE, *PSYSTEM_SERVICE_TABLE;

PSYSTEM_SERVICE_TABLE KeServiceDescriptorTableShadow = 0;
ULONG64 ul64W32pServiceTable = 0;

// 获取 KeServiceDescriptorTableShadow 首地址
ULONGLONG GetKeServiceDescriptorTableShadow()
{
	// 设置起始位置
	PUCHAR StartSearchAddress = (PUCHAR)__readmsr(0xC0000082) - 0x1808FE;

	// 设置结束位置
	PUCHAR EndSearchAddress = StartSearchAddress + 0x8192;
	// DbgPrint("扫描起始地址: %p --> 扫描结束地址: %p \n", StartSearchAddress, EndSearchAddress);

	PUCHAR ByteCode = NULL;

	UCHAR OpCodeA = 0, OpCodeB = 0, OpCodeC = 0;
	ULONGLONG addr = 0;
	ULONG templong = 0;

	for (ByteCode = StartSearchAddress; ByteCode < EndSearchAddress; ByteCode++)
	{
		// 使用MmIsAddressValid()函数检查地址是否有页面错误
		if (MmIsAddressValid(ByteCode) && MmIsAddressValid(ByteCode + 1) && MmIsAddressValid(ByteCode + 2))
		{
			OpCodeA = *ByteCode;
			OpCodeB = *(ByteCode + 1);
			OpCodeC = *(ByteCode + 2);

			// 对比特征值 寻找 nt!KeServiceDescriptorTable 函数地址
			/*
			lyshark.com kd> u KiSystemServiceRepeat
			nt!KiSystemServiceRepeat:
			fffff802`7c1d2b94 4c8d15e59c3b00  lea     r10,[nt!KeServiceDescriptorTable (fffff802`7c58c880)]
			fffff802`7c1d2b9b 4c8d1dde1e3a00  lea     r11,[nt!KeServiceDescriptorTableShadow (fffff802`7c574a80)]
			fffff802`7c1d2ba2 f7437880000000  test    dword ptr [rbx+78h],80h
			fffff802`7c1d2ba9 7413            je      nt!KiSystemServiceRepeat+0x2a (fffff802`7c1d2bbe)
			fffff802`7c1d2bab f7437800002000  test    dword ptr [rbx+78h],200000h
			fffff802`7c1d2bb2 7407            je      nt!KiSystemServiceRepeat+0x27 (fffff802`7c1d2bbb)
			fffff802`7c1d2bb4 4c8d1d051f3a00  lea     r11,[nt!KeServiceDescriptorTableFilter (fffff802`7c574ac0)]
			fffff802`7c1d2bbb 4d8bd3          mov     r10,r11
			*/
			if (OpCodeA == 0x4c && OpCodeB == 0x8d && OpCodeC == 0x1d)
			{
				// 获取高位地址fffff802
				memcpy(&templong, ByteCode + 3, 4);

				// 与低位64da4880地址相加得到完整地址
				addr = (ULONGLONG)templong + (ULONGLONG)ByteCode + 7;
				return addr;
			}
		}
	}
	return  0;
}

// 得到SSSDT个数
ULONGLONG GetSSSDTCount()
{
	PSYSTEM_SERVICE_TABLE pWin32k;
	ULONGLONG W32pServiceTable;

	pWin32k = (PSYSTEM_SERVICE_TABLE)((ULONG64)KeServiceDescriptorTableShadow + sizeof(SYSTEM_SERVICE_TABLE));
	W32pServiceTable = (ULONGLONG)(pWin32k->ServiceTableBase);
	// DbgPrint("Count => %d \n", pWin32k->NumberOfServices);

	return pWin32k->NumberOfServices;
}

VOID UnDriver(PDRIVER_OBJECT driver)
{
	DbgPrint(("驱动程序卸载成功! \n"));
}

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
	DbgPrint("hello lyshark.com \n");

	KeServiceDescriptorTableShadow = (PSYSTEM_SERVICE_TABLE)GetKeServiceDescriptorTableShadow();

	DbgPrint("[LyShark] SSSDT基地址 = 0x%p \n", KeServiceDescriptorTableShadow);

	ULONGLONG count = GetSSSDTCount();

	DbgPrint("[LyShark] SSSDT个数 = %d \n", count);

	// 循环枚举SSSDT
	for (size_t Index = 0; Index < count; Index++)
	{

		PSYSTEM_SERVICE_TABLE pWin32k;
		ULONGLONG W32pServiceTable;

		pWin32k = (PSYSTEM_SERVICE_TABLE)((ULONG64)KeServiceDescriptorTableShadow + sizeof(SYSTEM_SERVICE_TABLE));
		W32pServiceTable = (ULONGLONG)(pWin32k->ServiceTableBase);

		// 获取SSSDT地址
		//ln win32k!W32pServiceTable+((poi(win32k!W32pServiceTable+4*(1-1000))&0x00000000`ffffffff)>>4)-10000000
		//u win32k!W32pServiceTable+((poi(win32k!W32pServiceTable+4*(Index-0x1000))&0x00000000`ffffffff)>>4)-0x10000000

		//u poi(win32k!W32pServiceTable+4*(1-0x1000))
		//u poi(win32k!W32pServiceTable+4*(1-0x1000))&0x00000000`ffffffff
		//u (poi(win32k!W32pServiceTable+4*(1-0x1000))&0x00000000`ffffffff)>>4

		//u win32k!W32pServiceTable+((poi(win32k!W32pServiceTable+4*(1-0x1000))&0x00000000`ffffffff)>>4)-0x10000000

		ULONGLONG qword_temp = 0;
		LONG dw = 0;

		// SSSDT 下标从1000开始，而W32pServiceTable是从0开始
		// + 4 则是每次向下4字节就是下一个地址
		qword_temp = W32pServiceTable + 4 * (Index - 0x1000);
		
		dw = *(PLONG)qword_temp;
		// dw = qword_temp & 0x00000000ffffffff;
		dw = dw >> 4;
		qword_temp = W32pServiceTable + (LONG64)dw;

		DbgPrint("[LyShark] ID: %d | SSSDT: 0x%p \n", Index, qword_temp);
	}

	DriverObject->DriverUnload = UnDriver;
	return STATUS_SUCCESS;
}

枚举效果如下图所示所示，注意这一步必须要在GUI线程中执行，否则会异常，建议将枚举过程写成DLL文件，注入到explorer.exe进程内执行；