SSDT

学习资料：http://blog.csdn.net/zfdyq0/article/details/26515019

学习资料：WIN64内核编程基础 胡文亮

SSDT（系统服务描述表），刚开始接触什么进程保护XXX啥的，都是看到在说SSDT（虽然说目前很多杀软都已经采用稳定简单的回调姿势了）。这次就弄清楚两个问题：

如何在内核里动态获得 SSDT 的基址；

如何在内核里动态获得 SSDT 函数的地址；

在 WIN32 下，第一个问题就根本不是问题，因为 KeServiceDescriptorTable 直接被导

出了。但是 WIN64 下 KeServiceDescriptorTable 没有被导出。所以必须搜索得到它的地址。

反汇编：uf KisystemCall64

上面看到，貌似直接反汇编uf KiSystemServiceRepeat 试了下，一样可以找到SSDT基址，但是问题是，KiSystemServiceRepeat这个东西的地址找不到，而KiSystemCall64的地址直接可以直接读取指定的 msr 得出。

通过读取 C0000082 寄存器，能够得到 KiSystemCall64 的地址，然后从

KiSystemCall64 的地址开始，往下搜索 0x500 字节左右（特征码是 4c8d15），就能得到

KeServiceDescriptorTable 的地址了。同理，我们换一下特征码（4c8d1d），就能获得

KeServiceDescriptorTableShadow 的地址了。

然后是资料里面带的两个SSDT基址的函数：

方法1（这个方法蓝屏了，我直接用的方法2）

ULONGLONG GetKeServiceDescriptorTable64()
{
char KiSystemServiceStart_pattern[13] = "\x8B\xF8\xC1\xEF\x07\x83\xE7\x20\x25\xFF\x0F\x00\x00";
ULONGLONG CodeScanStart = (ULONGLONG)&_strnicmp;
ULONGLONG CodeScanEnd = (ULONGLONG)&KdDebuggerNotPresent;
UNICODE_STRING Symbol;
ULONGLONG i, tbl_address, b;
for (i = 0; i < CodeScanEnd - CodeScanStart; i++)
{
if (!memcmp((char*)(ULONGLONG)CodeScanStart +i, (char*)KiSystemServiceStart_pattern,13))
{
for (b = 0; b < 50; b++)
{
tbl_address = ((ULONGLONG)CodeScanStart+i+b);
if (*(USHORT*) ((ULONGLONG)tbl_address ) == (USHORT)0x8d4c)
return ((LONGLONG)tbl_address +7) + *(LONG*)(tbl_address +3);
}
}
}
return 0;
}

方法2

ULONGLONG MyGetKeServiceDescriptorTable64()
{
PUCHAR StartSearchAddress = (PUCHAR)__readmsr(0xC0000082);
    PUCHAR EndSearchAddress = StartSearchAddress + 0x500;
PUCHAR i = NULL;
UCHAR b1=0,b2=0,b3=0;
ULONG templong=0;
ULONGLONG addr=0;
for(i=StartSearchAddress;i<EndSearchAddress;i++)
{
if( MmIsAddressValid(i) && MmIsAddressValid(i+1) && MmIsAddressValid(i+2) )
{
b1=*i;
b2=*(i+1);
b3=*(i+2);
if( b1==0x4c && b2==0x8d && b3==0x15 ) //4c8d15
{
memcpy(&templong,i+3,4);
addr = (ULONGLONG)templong + (ULONGLONG)i + 7;
return addr;
}
}
}
return 0;
}

接下来就是讲述 SSDT 函数地址了。在获得地址之前，需要知道 SSDT 函数的 INDEX。获得这个 INDEX 的方法很简单，直接在 RING3 读取 NTDLL 的内容即可。使用 WINDBG 的方法如下：随便创建一个进程，然后使用 WINDBG 附加:

可以看到两次反汇编的结果几乎完全相同，唯一不同的地方是第二句。XXh 就是此函数的 index。知道 INDEX 之后，就可以计算地址了（资料上也是给了两个方法，建议使用方法2）。

方法1

VOID Initxxxx()
{
UCHAR strShellCode[36]="\x48\x8B\xC1\x4C\x8D\x12\x8B\xF8\xC1\xEF\x07\x83\xE7\x20\x4E\x8B\x14\x17\x4D\x63\x1C\x82\x49\x8B\xC3\x49\xC1\xFB\x04\x4D\x03\xD3\x49\x8B\xC2\xC3";
/*
mov rax, rcx ;rcx=index
lea r10,[rdx] ;rdx=ssdt
mov edi,eax
shr edi,7
and edi,20h
mov r10, qword ptr [r10+rdi]
movsxd r11,dword ptr [r10+rax*4]
mov rax,r11
sar r11,4
add r10,r11
mov rax,r10
ret
*/
scfn=ExAllocatePool(NonPagedPool,36);
memcpy(scfn,strShellCode,36);
}
ULONGLONG GetSSDTFunctionAddress64(ULONGLONG NtApiIndex)
{
ULONGLONG ret=0;
ULONGLONG ssdt= MyGetKeServiceDescriptorTable64();
if(scfn==NULL)
Initxxxx();
ret=scfn(NtApiIndex, ssdt);
return ret;
}

方法2

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

ULONGLONG GetSSDTFunctionAddress64_2(ULONGLONG Index)
{
LONG dwTemp=0;
ULONGLONG qwTemp=0,stb=0,ret=0;
PSYSTEM_SERVICE_TABLE ssdt=(PSYSTEM_SERVICE_TABLE)MyGetKeServiceDescriptorTable64();
stb=(ULONGLONG)(ssdt->ServiceTableBase);
qwTemp = stb + 4 * Index;
dwTemp = *(PLONG)qwTemp;
dwTemp = dwTemp >> 4;
ret = stb + (LONG64)dwTemp;
return ret;
}

最后，总结一下 WIN32 和 WIN64 在 SSDT 方面的不同（我直接截图过来）。大家可以把 SSDT（其实 SHADOWSSDT 同理）想像成一排保险柜，每个柜子都有编号（从 0 开始），柜子的长度为四字节，每个柜子里都放了一个 LONG 数据。但不同的是，WIN32 的“柜子”里放的数据是某个函数的绝对地址，而 WIN64 的“柜子”里放的数据是某个函数的偏移地址。这个偏移地址要经过一定的计算才能变成绝对地址。

测试代码：

#include <ntddk.h>
#include <windef.h>
#include "MyDriver.h"    

#pragma intrinsic(__readmsr)
typedef UINT64 (__fastcall *SCFN)(UINT64,UINT64);
SCFN scfn;

ULONGLONG MyGetKeServiceDescriptorTable64()
{
PUCHAR StartSearchAddress = (PUCHAR)__readmsr(0xC0000082);
    PUCHAR EndSearchAddress = StartSearchAddress + 0x500;
PUCHAR i = NULL;
UCHAR b1=0,b2=0,b3=0;
ULONG templong=0;
ULONGLONG addr=0;
for(i=StartSearchAddress;i<EndSearchAddress;i++)
{
if( MmIsAddressValid(i) && MmIsAddressValid(i+1) && MmIsAddressValid(i+2) )
{
b1=*i;
b2=*(i+1);
b3=*(i+2);
if( b1==0x4c && b2==0x8d && b3==0x15 ) //4c8d15
{
memcpy(&templong,i+3,4);
addr = (ULONGLONG)templong + (ULONGLONG)i + 7;
return addr;
}
}
}
return 0;
}

VOID Initxxxx()
{
UCHAR strShellCode[36]="\x48\x8B\xC1\x4C\x8D\x12\x8B\xF8\xC1\xEF\x07\x83\xE7\x20\x4E\x8B\x14\x17\x4D\x63\x1C\x82\x49\x8B\xC3\x49\xC1\xFB\x04\x4D\x03\xD3\x49\x8B\xC2\xC3";
/*
mov rax, rcx ;rcx=index
lea r10,[rdx] ;rdx=ssdt
mov edi,eax
shr edi,7
and edi,20h
mov r10, qword ptr [r10+rdi]
movsxd r11,dword ptr [r10+rax*4]
mov rax,r11
sar r11,4
add r10,r11
mov rax,r10
ret
*/
scfn=ExAllocatePool(NonPagedPool,36);
memcpy(scfn,strShellCode,36);
}

ULONGLONG GetSSDTFunctionAddress64(ULONGLONG NtApiIndex)
{
ULONGLONG ret=0;
ULONGLONG ssdt= MyGetKeServiceDescriptorTable64();
if(scfn==NULL)
Initxxxx();
ret=scfn(NtApiIndex, ssdt);
return ret;
}

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

ULONGLONG GetSSDTFunctionAddress64_2(ULONGLONG Index)
{
LONG dwTemp=0;
ULONGLONG qwTemp=0,stb=0,ret=0;
PSYSTEM_SERVICE_TABLE ssdt=(PSYSTEM_SERVICE_TABLE)MyGetKeServiceDescriptorTable64();
stb=(ULONGLONG)(ssdt->ServiceTableBase);
qwTemp = stb + 4 * Index;
dwTemp = *(PLONG)qwTemp;
dwTemp = dwTemp >> 4;
ret = stb + (LONG64)dwTemp;
return ret;
}

VOID DriverUnload(PDRIVER_OBJECT pDriverObj)
{
UNICODE_STRING strLink;
RtlInitUnicodeString(&strLink, LINK_NAME);
IoDeleteSymbolicLink(&strLink);
IoDeleteDevice(pDriverObj->DeviceObject);
}

NTSTATUS DispatchCreate(PDEVICE_OBJECT pDevObj, PIRP pIrp)
{
pIrp->IoStatus.Status = STATUS_SUCCESS;
pIrp->IoStatus.Information = 0;
IoCompleteRequest(pIrp, IO_NO_INCREMENT);
return STATUS_SUCCESS;
}

NTSTATUS DispatchClose(PDEVICE_OBJECT pDevObj, PIRP pIrp)
{
pIrp->IoStatus.Status = STATUS_SUCCESS;
pIrp->IoStatus.Information = 0;
IoCompleteRequest(pIrp, IO_NO_INCREMENT);
return STATUS_SUCCESS;
}

NTSTATUS DispatchIoctl(PDEVICE_OBJECT pDevObj, PIRP pIrp)
{
NTSTATUS status = STATUS_INVALID_DEVICE_REQUEST;
PIO_STACK_LOCATION pIrpStack;
ULONG uIoControlCode;
PVOID pIoBuffer;
ULONG uInSize;
ULONG uOutSize;
pIrpStack = IoGetCurrentIrpStackLocation(pIrp);
uIoControlCode = pIrpStack->Parameters.DeviceIoControl.IoControlCode;
pIoBuffer = pIrp->AssociatedIrp.SystemBuffer;
uInSize = pIrpStack->Parameters.DeviceIoControl.InputBufferLength;
uOutSize = pIrpStack->Parameters.DeviceIoControl.OutputBufferLength;
switch(uIoControlCode)
{
;
}
if(status == STATUS_SUCCESS)
pIrp->IoStatus.Information = uOutSize;
else
pIrp->IoStatus.Information = 0;
pIrp->IoStatus.Status = status;
IoCompleteRequest(pIrp, IO_NO_INCREMENT);
return status;
}

NTSTATUS DriverEntry(PDRIVER_OBJECT pDriverObj, PUNICODE_STRING pRegistryString)
{
NTSTATUS status = STATUS_SUCCESS;
UNICODE_STRING ustrLinkName;
UNICODE_STRING ustrDevName;
PDEVICE_OBJECT pDevObj;
pDriverObj->MajorFunction[IRP_MJ_CREATE] = DispatchCreate;
pDriverObj->MajorFunction[IRP_MJ_CLOSE] = DispatchClose;
pDriverObj->MajorFunction[IRP_MJ_DEVICE_CONTROL] = DispatchIoctl;
pDriverObj->DriverUnload = DriverUnload;
RtlInitUnicodeString(&ustrDevName, DEVICE_NAME);
status = IoCreateDevice(pDriverObj, 0, &ustrDevName, FILE_DEVICE_UNKNOWN, 0, FALSE, &pDevObj);
if(!NT_SUCCESS(status))    return status;
if(IoIsWdmVersionAvailable(1, 0x10))
RtlInitUnicodeString(&ustrLinkName, LINK_GLOBAL_NAME);
else
RtlInitUnicodeString(&ustrLinkName, LINK_NAME);
status = IoCreateSymbolicLink(&ustrLinkName, &ustrDevName);
if(!NT_SUCCESS(status))
{
IoDeleteDevice(pDevObj);
return status;
}
//test
DbgPrint("[method 1]SSDT: %llx\n",MyGetKeServiceDescriptorTable64());

DbgPrint("[method 1]NtOpenProcess: %llx\n",GetSSDTFunctionAddress64(0x23));    //WIN7X64 HARDCODE
DbgPrint("[method 1]NtTerminateProcess: %llx\n",GetSSDTFunctionAddress64(0x29));    //WIN7X64 HARDCODE

DbgPrint("[method 2]NtOpenProcess: %llx\n",GetSSDTFunctionAddress64_2(0x23));    //WIN7X64 HARDCODE
DbgPrint("[method 2]NtTerminateProcess: %llx\n",GetSSDTFunctionAddress64_2(0x29));//WIN7X64 HARDCODE
//test
return STATUS_SUCCESS;
}

执行结果：