ring0 ShadowSSDTHook

Posted 2020-10-04 HsinTsao

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SSDT：主要处理 Kernel32.dll中的系统调用，如openProcess,ReadFile等，主要在ntoskrnl.exe中实现（微软有给出 ntoskrnl源代码）

ShadowSSDT: 1.主要处理，user32.dll,GDI32.dll中调用的函数，如postMessage,SendMessage,FindWindow,主要在win32k.sys中实现.（微软未给出win32k代码）
2.需要注意的是shadowSSDT并未导出,可用ida在win32k.sys中的导出表搜索，且结构与ssdt相似，但是不能通过windbg dd命令查看值
3.ShadowSSDT表只能在GUI(即有界面的程序进程)环境下才有值，故我们需要调用KeAttachProcess来切换到GUI线程里。
4.用windbg 命令 .process 861ff020 （861ff020 是通过命令！process 0 0得到的）切换到GUI线程上下文
过程：1）（输入windbg命令）！process 0 0得到其中一个有图形界面的程序
（数据如下）
PROCESS 861ff020 SessionId: 0 Cid: 0b58 Peb: 7ffde000 ParentCid: 05e4
DirBase: 10080380 ObjectTable: e1dd2808 HandleCount: 73.
Image: windbg.exe
2）（输入命令）
lkd> .process 861ff020
Implicit process is now 861ff020
（切换成功）
3）切换成功后，使用dd KeServiceDescriptorTableShadow即可得到该表数据，否则无法得到，得到数据如下
  lkd> dd KeServiceDescriptorTableShadow
80553f60 80502b8c 00000000 0000011c 80503000--〉SSDT
80553f70 bf999b80 00000000 0000029b bf99a890 --〉ShadowSSDT
80553f80 00000000 00000000 00000000 00000000
80553f90 00000000 00000000 00000000 00000000
80553fa0 80502b8c 00000000 0000011c 80503000
80553fb0 00000000 00000000 00000000 00000000
80553fc0 00000000 00000000 00000000 00000000
80553fd0 00000000 00000000 00000000 00000000
其实KeServiceDescriptorTableShadow 包含4个系统服务表，但是我们只用前2个(SSDT,ShadowSSDT)
       4) 总结：
  1) ShadowSSDT在KeServiceDescriptorTableShadow[1]中，而KeServiceDescriptorTableShadow[0]为ssdt
2)如果要查看win32k服务，必须要切换到GUI线程上下文
    5.如何得到ShadowSSDT地址：在insight source中可查询到wrk中有KeAddSystemServiceTable函数，里面有对KeServiceDescriptorTableShadow 的调用
思路：利用搜索特征码的方式搜索KeAddSystemServiceTable，取出KeServiceDescriptorTableShadow

64位
HOOK 和 UNHOOK SHADOW SSDT 跟之前的 HOOK/UNHOOK SSDT 类似，区别是查找SSSDT的特征码，以及根据索引计算函数地址的公式，还有一个就是吧跳转函数写在什么位置，SSDT的时候是写在蓝屏函数里了。
一、获得 w KeServiceDescriptorTableShadow的地址
这个跟获得 KeServiceDescriptorTable 差不多，唯一不同就是特征码：


#include "ShadowSSDTHook.h"

int NtUserFindWindowExIndex = 378;

pfnNtUserFindWindowEx  OldNtUserFindWindowEx = NULL;

//ShadowSSDT
PSERVICE_DESCRIPTOR_TABLE KeServiceDescriptorShadowTable;

NTSTATUS
    DriverEntry(PDRIVER_OBJECT  DriverObject,PUNICODE_STRING  RegisterPath)
{
    PDEVICE_OBJECT  DeviceObject;
    NTSTATUS        Status;
    int             i = 0;

    PEPROCESS       EProcess;

    UNICODE_STRING  DeviceName;
    UNICODE_STRING  LinkName;

    RtlInitUnicodeString(&DeviceName,DEVICE_NAME);
    RtlInitUnicodeString(&LinkName,LINK_NAME);

    //创建设备对象;

    Status = IoCreateDevice(DriverObject,0,
    &DeviceName,FILE_DEVICE_UNKNOWN,0,FALSE,&DeviceObject);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    Status = IoCreateSymbolicLink(&LinkName,&DeviceName);

    for (i = 0; i<IRP_MJ_MAXIMUM_FUNCTION; i++)
    {
        DriverObject->MajorFunction[i] = DefaultPassThrough;
    }

    DriverObject->DriverUnload = UnloadDriver;

    KeServiceDescriptorShadowTable = GetShadowTableAddress();
    if (KeServiceDescriptorShadowTable)
    {
        if (LookupProcessByName("explorer.exe", &EProcess) == STATUS_SUCCESS)
        {
            KeAttachProcess(EProcess);//附加到目标进程

            HookShadowSSDTTable(&KeServiceDescriptorShadowTable[1],
                &NtUserFindWindowExIndex,
                &(ULONG_PTR)OldNtUserFindWindowEx, 
                (ULONG_PTR)FakeNtUserFindWindowEx);

            KeDetachProcess();//解除附加
        }

    }




#ifdef WIN64
//    __asm
//    {
//        xchg rax,rbx
//    }
    DbgPrint("WIN64: ShadowSSDTHook IS RUNNING!!!");
#else
//    __asm
//    {
//        xor eax,eax
//    }
    DbgPrint("WIN32: ShadowSSDTHook SIS RUNNING!!!");

#endif
    
    return STATUS_SUCCESS;
}

NTSTATUS
    DefaultPassThrough(PDEVICE_OBJECT  DeviceObject,PIRP Irp)
{
    Irp->iostatus.Status = STATUS_SUCCESS;
    Irp->IoStatus.Information = 0;
    IoCompleteRequest(Irp,IO_NO_INCREMENT);

    return STATUS_SUCCESS;
}

VOID
    UnloadDriver(PDRIVER_OBJECT DriverObject)
{
    PEPROCESS EProcess;

    UNICODE_STRING  LinkName;
    PDEVICE_OBJECT    NextDeviceObject    = NULL;
    PDEVICE_OBJECT  CurrentDeviceObject = NULL;
    RtlInitUnicodeString(&LinkName,LINK_NAME);

    IoDeleteSymbolicLink(&LinkName);
    CurrentDeviceObject = DriverObject->DeviceObject;
    while (CurrentDeviceObject != NULL) 
    {
    
        NextDeviceObject = CurrentDeviceObject->NextDevice;
        IoDeleteDevice(CurrentDeviceObject);
        CurrentDeviceObject = NextDeviceObject;
    }


    KeServiceDescriptorShadowTable = GetShadowTableAddress();
    if (KeServiceDescriptorShadowTable)
    {
        //获取一个gui线程的进程对象。
        if (LookupProcessByName("explorer.exe", &EProcess) == STATUS_SUCCESS)
        {
            KeAttachProcess(EProcess);//附加到目标进程
            UnHookShadowSSDTTable(&KeServiceDescriptorShadowTable[1],
                &NtUserFindWindowExIndex, (ULONG_PTR)OldNtUserFindWindowEx);

            KeDetachProcess();//解除附加
        }
    }
    
    DbgPrint("ShadowSSDTHook IS STOPPED!!!");
}

PVOID
GetShadowTableAddress()
{
    ULONG_PTR ulData = 0;
    ULONG_PTR i = 0;
    PUCHAR  Temp = (PUCHAR)KeAddSystemServiceTable;  //类似王艳萍的内存修改器做法
    //扫描特征码
    for (i = 0; i<4096; i++, Temp++)
    {
        __try
        {
            ulData = *(ULONG_PTR*)Temp;
        }
        __except (EXCEPTION_EXECUTE_HANDLER)
        {
            return FALSE;
        }

        if (MmIsAddressValid((PVOID)ulData))
        {
            if (memcmp((PVOID)ulData, KeServiceDescriptorTable, 16) == 0)
            {
                if ((PVOID)ulData == KeServiceDescriptorTable)  //排除SSDT
                {
                    continue;
                }

                return (PVOID)ulData;
            }
        }
    }

    return FALSE;
}

NTSTATUS LookupProcessByName(
    IN PCHAR ProcessName,
    OUT PEPROCESS *EProcess
)
{
    NTSTATUS    status;
    ULONG        uCount = 0;
    ULONG        uLength = 0;
    PLIST_ENTRY    ListActiveProcess;
    PEPROCESS    CurrentEProcess = NULL;
    ULONG       ulNextProcess = 0;
    ULONG       g_Offset_Eprocess_Flink = 0x88;  //XP操作系统
    char        lpszProName[100];
    char *lpszAttackProName = NULL;

    uLength = strlen(ProcessName);

    CurrentEProcess = PsGetCurrentProcess();
    ulNextProcess = (ULONG)CurrentEProcess;


    __try
    {
        memset(lpszProName, 0, sizeof(lpszProName));
        if (uLength > 15)
        {
            strncat(lpszProName, ProcessName, 15);
        }
        while (1)
        {
            lpszAttackProName = NULL;
            lpszAttackProName = (char *)PsGetProcessImageFileName(CurrentEProcess);

            if (uLength > 15)
            {
                if (lpszAttackProName && strlen(lpszAttackProName) == uLength)
                {
                    if (_strnicmp(lpszProName, lpszAttackProName, uLength) == 0)
                    {
                        *EProcess = CurrentEProcess;
                        status = STATUS_SUCCESS;
                        break;
                    }
                }
            }
            else
            {
                if (lpszAttackProName && strlen(lpszAttackProName) == uLength)
                {
                    if (_strnicmp(ProcessName, lpszAttackProName, uLength) == 0)
                    {
                        *EProcess = CurrentEProcess;
                        status = STATUS_SUCCESS;
                        break;
                    }
                }
            }
            if ((uCount >= 1) && (ulNextProcess == (ULONG)CurrentEProcess))
            {
                *EProcess = 0x00000000;
                status = STATUS_NOT_FOUND;
                break;
            }
            ListActiveProcess = (LIST_ENTRY *)((ULONG)CurrentEProcess + g_Offset_Eprocess_Flink);
            (ULONG)CurrentEProcess = (ULONG)ListActiveProcess->Flink;
            (ULONG)CurrentEProcess = (ULONG)CurrentEProcess - g_Offset_Eprocess_Flink;
            uCount++;
        }
    }
    __except (EXCEPTION_EXECUTE_HANDLER)
    {
        KdPrint(("LookupProcessByName:%08x\\r\\n", GetExceptionCode()));
        status = STATUS_NOT_FOUND;
    }
    return status;
}

BOOLEAN HookShadowSSDTTable(PSERVICE_DESCRIPTOR_TABLE ServiceDescriptorShadowSSDTTable,
    int *Index, ULONG_PTR *OldFuctionAddress,
    ULONG_PTR FakeFuctionAddress)
{
    BOOLEAN bRetOK = FALSE;

    __try
    {
        //检查
        if (MmIsAddressValid(ServiceDescriptorShadowSSDTTable) &&
            MmIsAddressValid(ServiceDescriptorShadowSSDTTable->ServiceTable))
        {
            //检查*index是否在表的有效范围
            if (*Index >= 0 && *Index <(int)ServiceDescriptorShadowSSDTTable->TableSize)
            {
                //保存原始函数，因为我们的hook过滤函数需要用到。
                *OldFuctionAddress = ServiceDescriptorShadowSSDTTable->ServiceTable[*Index];

                WPOFF();
                InterlockedExchange(&ServiceDescriptorShadowSSDTTable->ServiceTable[*Index],
                    FakeFuctionAddress);
                bRetOK = TRUE;
                WPON();
            }
        }

    }
    __except (EXCEPTION_EXECUTE_HANDLER) {

    }
    return bRetOK;

}


NTSTATUS FakeNtUserFindWindowEx(ULONG_PTR hWndParent, ULONG_PTR hWndChild, PUNICODE_STRING uniClassName,
    PUNICODE_STRING uniWindowName, ULONG_PTR Type)
{
    char*      ProcessName = NULL;
    PEPROCESS  EProcess;
    EProcess = IoGetCurrentProcess();

    ProcessName = PsGetProcessImageFileName(EProcess);
　　//进行过滤
    if (strstr(ProcessName, "Test.exe") != NULL)
    {
        DbgPrint("HookFindWindow\\r\\n");
        return STATUS_SUCCESS;
    }

    return OldNtUserFindWindowEx(hWndParent, hWndChild, uniClassName, uniWindowName, Type);

}


//去掉内存保护
void WPOFF()
{
    __asm {
        cli
        mov  eax, cr0
        and  eax, not 10000h
        mov  cr0, eax
    }
}
//恢复内存保护  
void WPON()
{
    __asm {
        mov  eax, cr0
        or eax, 10000h
        mov  cr0, eax
        sti
    }
}


BOOLEAN UnHookShadowSSDTTable(PSERVICE_DESCRIPTOR_TABLE ServiceDescriptorShadowSSDTTable,
    int *Index, ULONG_PTR OldFuctionAddress)
{
    BOOLEAN bRetOK = FALSE;

    __try
    {
        //检查
        if (MmIsAddressValid(ServiceDescriptorShadowSSDTTable) &&
            MmIsAddressValid(ServiceDescriptorShadowSSDTTable->ServiceTable))
        {
            //检查*index是否在表的有效范围
            if (*Index >= 0 && *Index <(int)ServiceDescriptorShadowSSDTTable->TableSize)
            {
                WPOFF();
                InterlockedExchange(&ServiceDescriptorShadowSSDTTable->ServiceTable[*Index],
                    OldFuctionAddress);
                bRetOK = TRUE;
                WPON();
            }
        }

    }
    __except (EXCEPTION_EXECUTE_HANDLER)
    {

    }
    return bRetOK;

}


#include <ntifs.h>

#ifndef CXX_ShadowSSDTHook_H
#define CXX_ShadowSSDTHook_H

#define DEVICE_NAME  L"\\\\Device\\\\ShadowSSDTHookDevice"
#define LINK_NAME    L"\\\\??\\\\ShadowSSDTHookLink"

typedef struct _SERVICE_DESCRIPTOR_TABLE {
    PULONG   ServiceTable;
    PULONG  CounterTable;
    ULONG   TableSize;
    PUCHAR  ArgumentTable;
} SERVICE_DESCRIPTOR_TABLE, *PSERVICE_DESCRIPTOR_TABLE;

//SSDT表
extern PSERVICE_DESCRIPTOR_TABLE KeServiceDescriptorTable;

extern
UCHAR *PsGetProcessImageFileName(PEPROCESS eprocess);


typedef
NTSTATUS(*pfnNtUserFindWindowEx)(ULONG_PTR hWndParent, ULONG_PTR hWndChild, PUNICODE_STRING uniClassName,
    PUNICODE_STRING uniWindowName, ULONG_PTR Type);


__declspec(dllimport) _stdcall KeAddSystemServiceTable(PVOID, PVOID, PVOID, PVOID, PVOID);



VOID
    UnloadDriver(PDRIVER_OBJECT DriverObject);

PVOID GetShadowTableAddress();

NTSTATUS LookupProcessByName(IN PCHAR ProcessName, OUT PEPROCESS * EProcess);

BOOLEAN HookShadowSSDTTable(PSERVICE_DESCRIPTOR_TABLE ServiceDescriptorShadowSSDTTable, int * Index, ULONG_PTR * OldFuctionAddress, ULONG_PTR FakeFuctionAddress);

NTSTATUS FakeNtUserFindWindowEx(ULONG_PTR hWndParent, ULONG_PTR hWndChild, PUNICODE_STRING uniClassName, PUNICODE_STRING uniWindowName, ULONG_PTR Type);

void WPOFF();

void WPON();

BOOLEAN UnHookShadowSSDTTable(PSERVICE_DESCRIPTOR_TABLE ServiceDescriptorShadowSSDTTable, int * Index, ULONG_PTR OldFuctionAddress);

NTSTATUS
    DefaultPassThrough(PDEVICE_OBJECT  DeviceObject,PIRP Irp);

#endif

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