参考文献：

《对Native API NtSystemDebugControl的分析》 -- 于?

《编程破解CMOS密码》

#include<stdio.h>
#include<windows.h>

char passwd[9];
char decode[9];

typedef int NTSTATUS;
typedef enum _SYSDBG_COMMAND
{
	SysDbgSysReadIoSpace = 14,
		SysDbgSysWriteIoSpace = 15
}SYSDBG_COMMAND, *PSYSDBG_COMMAND;

typedef NTSTATUS (NTAPI * PZwSystemDebugControl) 
	(
	SYSDBG_COMMAND ControlCode,
	PVOID InputBuffer,
	ULONG InputBufferLength,
	PVOID OutputBuffer,
	ULONG OutputBufferLength,
	PULONG ReturnLength
	);
PZwSystemDebugControl ZwSystemDebugControl = NULL;

typedef struct _IO_STRUCT
{
	DWORD IoAddr;       // IN: Aligned to NumBYTEs,I/O address
	DWORD Reserved1;    // Never accessed by the kernel
	PVOID pBuffer;      // IN (write) or OUT (read): Ptr to buffer
	DWORD NumBYTEs;     // IN: # BYTEs to read/write. Only use 1, 2, or 4.
	DWORD Reserved4;    // Must be 1
	DWORD Reserved5;    // Must be 0
	DWORD Reserved6;    // Must be 1
	DWORD Reserved7;    // Never accessed by the kernel
}
IO_STRUCT, *PIO_STRUCT;

BOOL EnablePrivilege (PCSTR name)
{
	HANDLE hToken;
	BOOL rv;
	
	TOKEN_PRIVILEGES priv = { 1, {0, 0, SE_PRIVILEGE_ENABLED} };
	LookupPrivilegeValue (0,name,&priv.Privileges[0].Luid);
	OpenProcessToken(GetCurrentProcess (),TOKEN_ADJUST_PRIVILEGES,&hToken);
	AdjustTokenPrivileges (hToken,FALSE,&priv,sizeof priv,0,0);
	rv = GetLastError () == ERROR_SUCCESS; 
	CloseHandle (hToken);
	return rv;
}

BYTE InPortB (int Port)
{
	BYTE Value;
	IO_STRUCT io;
	
	io.IoAddr = Port;
	io.Reserved1 = 0;
	io.pBuffer = (PVOID) (PULONG) & Value;
	io.NumBYTEs = sizeof (BYTE);
	io.Reserved4 = 1;
	io.Reserved5 = 0;
	io.Reserved6 = 1;
	io.Reserved7 = 0;
	
	ZwSystemDebugControl(SysDbgSysReadIoSpace,&io,sizeof(io),NULL,0,NULL);
	return Value;
}

void OutPortB (int Port, BYTE Value)
{
	IO_STRUCT io;
	
	io.IoAddr = Port;
	io.Reserved1 = 0;
	io.pBuffer = (PVOID) (PULONG) & Value;
	io.NumBYTEs = sizeof (BYTE);
	io.Reserved4 = 1;
	io.Reserved5 = 0;
	io.Reserved6 = 1;
	io.Reserved7 = 0;
	
	ZwSystemDebugControl(SysDbgSysWriteIoSpace,&io,sizeof (io),NULL,0,NULL);
}

int main()
{
	HMODULE	hNtdll;
	int	count = 0;
	UINT	uData  = 0;

	EnablePrivilege (SE_DEBUG_NAME);	
	hNtdll = LoadLibrary ("ntdll.dll");
	if(hNtdll == NULL)
		{
		printf("Load ntdll.dll error!!\n");
		return 0;
		}

	ZwSystemDebugControl = (PZwSystemDebugControl)GetProcAddress(hNtdll, "ZwSystemDebugControl");
	if(ZwSystemDebugControl == NULL)
		{
		printf("Load ZwSystemDebugControl function error!\n");
		return 0;
		}
	//读写端口
	OutPortB(0x70,29);
	uData = InPortB(0x71);
	OutPortB(0x70,28);
	uData = (uData<<8)+InPortB(0x71);
	//计算hash值
	while (uData>0)   //将原始数据转换为有效数据
		{      
		if(uData<0x80)
			{
			passwd[count]=uData;
			break;
			}
		else	{
			unsigned char temp=uData&0x3f;
			if(temp<=0x20)	
				temp|=0x30;	
			passwd[count++]=temp;
			uData-=temp;
			uData>>=2;
			}
		}
	for(int i=0;count>=0;i++)      //将得到的CMOS密码输出
		decode[i]=passwd[count--];
	//输出密码
	printf("The CMOS's password:%s\n",decode);
	return 1;
}

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