有时候我们需要对其它应用程序发送和接收的网络数据进行拦截,比如要对IE发送的HTTP头进行分析,得到请求的地址等.这次我们可以用一些例如WPE, Sniffer之类的工具来达到目的.但是工具功能有限,要想实现更强大的功能,还是我们自己动手来DIY吧.
拦截网络数据封包的方法有三种,一是将网卡设为混杂模式,这次就可以监视到局域网上所有的数据包,二是HOOK目标进程的发送和接收的API函数,第三种方法是自己实现一个代理的DLL.在这里我们使用HOOK API的方法,这样易于实现,而且也不会得到大量的无用数据(如第一种方法就会监视到所有的网络数据).
下面是一个尽量简化了的API HOOK的模版,原理是利用消息钩子将DLL中的代码注入到目标进程中,再用GetProcAddress得到API函数入口地址,将函数入口址改为自己定义的函数入口,这样就得到了API函数的相应参数,处理完后,再改回真实API函数入口地址,并调用它.
HOOK.DLL的代码:
library Hook;
uses
SysUtils,
windows,
Messages,
APIHook in ‘‘APIHook.pas‘‘;
type
PData = ^TData;
TData = record
Hook: THandle;
Hooked:
Boolean;
end;
var
DLLData: PData;
{------------------------------------}
{过程名:HookProc
{过程功能:HOOK过程
{过程参数:nCode,
wParam, lParam消息的相
{
关参数
{------------------------------------}
procedure HookProc(nCode,
wParam, lParam: LongWORD);stdcall;
begin
if not DLLData^.Hooked
then
begin
HookAPI;
DLLData^.Hooked :=
True;
end;
//调用下一个Hook
CallNextHookEx(DLLData^.Hook, nCode, wParam,
lParam);
end;
{------------------------------------}
{函数名:InstallHook
{函数功能:在指定窗口上安装HOOK
{函数参数:sWindow:要安装HOOK的窗口
{返回值:成功返回TRUE,失败返回FALSE
{------------------------------------}
function
InstallHook(SWindow: LongWORD):Boolean;stdcall;
var
ThreadID:
LongWORD;
begin
Result := False;
DLLData^.Hook := 0;
ThreadID :=
GetWindowThreadProcessId(sWindow, nil);
//给指定窗口挂上钩子
DLLData^.Hook :=
SetWindowsHookEx(WH_GETMESSAGE, @HookProc, Hinstance, ThreadID);
if
DLLData^.Hook > 0 then
Result := True
//是否成功HOOK
else
exit;
end;
{------------------------------------}
{过程名:UnHook
{过程功能:卸载HOOK
{过程参数:无
{------------------------------------}
procedure
UnHook;stdcall;
begin
UnHookAPI;
//卸载Hook
UnhookWindowsHookEx(DLLData^.Hook);
end;
{------------------------------------}
{过程名:DLL入口函数
{过程功能:进行DLL初始化,释放等
{过程参数:DLL状态
{------------------------------------}
procedure
MyDLLHandler(Reason: Integer);
var
FHandle: LongWORD;
begin
case
Reason of
DLL_PROCESS_ATTACH:
begin //建立文件映射,以实现DLL中的全局变量
FHandle :=
CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, $ffff,
‘‘MYDLLDATA‘‘);
if FHandle = 0 then
if GetLastError = ERROR_ALREADY_EXISTS
then
begin
FHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, False,
‘‘MYDLLDATA‘‘);
if FHandle = 0 then Exit;
end else Exit;
DLLData :=
MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
if DLLData = nil
then
CloseHandle(FHandle);
end;
DLL_PROCESS_DETACH:
begin
if
Assigned(DLLData) then
begin
UnmapViewOfFile(DLLData);
DLLData :=
nil;
end;
end;
end;
end;
{$R *.res}
exports
InstallHook, UnHook, HookProc;
begin
DLLProc :=
@MyDLLHandler;
MyDLLhandler(DLL_PROCESS_ATTACH);
DLLData^.Hooked :=
False;
end.
----------------------------------------------------------------------------------------
APIHook.Pas的代码:
unit APIHook;
interface
uses
SysUtils,
Windows, WinSock;
type
//要HOOK的API函数定义
TSockProc = function (s: TSocket; var Buf; len,
flags: Integer): Integer; stdcall;
PJmpCode = ^TJmpCode;
TJmpCode = packed record
JmpCode:
BYTE;
Address: TSockProc;
MovEAX: Array [0..2] of BYTE;
end;
//--------------------函数声明---------------------------
procedure
HookAPI;
procedure UnHookAPI;
var
OldSend, OldRecv: TSockProc; //原来的API地址
JmpCode:
TJmpCode;
OldProc: array [0..1] of TJmpCode;
AddSend, AddRecv: pointer;
//API地址
TmpJmp: TJmpCode;
ProcessHandle: THandle;
implementation
{---------------------------------------}
{函数功能:Send函数的HOOK
{函数参数:同Send
{函数返回值:integer
{---------------------------------------}
function
MySend(s: TSocket; var Buf; len, flags: Integer): Integer;
stdcall;
var
dwSize:
cardinal;
begin
//这儿进行发送的数据处理
MessageBeep(1000);
//简单的响一声
//调用直正的Send函数
WriteProcessMemory(ProcessHandle, AddSend,
@OldProc[0], 8, dwSize);
Result := OldSend(S, Buf, len,
flags);
JmpCode.Address := @MySend;
WriteProcessMemory(ProcessHandle,
AddSend, @JmpCode, 8, dwSize);
end;
{---------------------------------------}
{函数功能:Recv函数的HOOK
{函数参数:同Recv
{函数返回值:integer
{---------------------------------------}
function
MyRecv(s: TSocket; var Buf; len, flags: Integer): Integer;
stdcall;
var
dwSize:
cardinal;
begin
//这儿进行接收的数据处理
MessageBeep(1000);
//简单的响一声
//调用直正的Recv函数
WriteProcessMemory(ProcessHandle, AddRecv,
@OldProc[1], 8, dwSize);
Result := OldRecv(S, Buf, len,
flags);
JmpCode.Address := @MyRecv;
WriteProcessMemory(ProcessHandle,
AddRecv, @JmpCode, 8, dwSize);
end;
{------------------------------------}
{过程功能:HookAPI
{过程参数:无
{------------------------------------}
procedure
HookAPI;
var
DLLModule: THandle;
dwSize:
cardinal;
begin
ProcessHandle := GetCurrentProcess;
DLLModule :=
LoadLibrary(‘‘ws2_32.dll‘‘);
AddSend := GetProcAddress(DLLModule,
‘‘send‘‘); //取得API地址
AddRecv := GetProcAddress(DLLModule,
‘‘recv‘‘);
JmpCode.JmpCode := $B8;
JmpCode.MovEAX[0] :=
$FF;
JmpCode.MovEAX[1] := $E0;
JmpCode.MovEAX[2] :=
0;
ReadProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8,
dwSize);
JmpCode.Address := @MySend;
WriteProcessMemory(ProcessHandle,
AddSend, @JmpCode, 8, dwSize); //修改Send入口
ReadProcessMemory(ProcessHandle,
AddRecv, @OldProc[1], 8, dwSize);
JmpCode.Address :=
@MyRecv;
WriteProcessMemory(ProcessHandle, AddRecv, @JmpCode, 8, dwSize);
//修改Recv入口
OldSend := AddSend;
OldRecv := AddRecv;
end;
{------------------------------------}
{过程功能:取消HOOKAPI
{过程参数:无
{------------------------------------}
procedure
UnHookAPI;
var
dwSize:
Cardinal;
begin
WriteProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8,
dwSize);
WriteProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8,
dwSize);
end;
end.
---------------------------------------------------------------------------------------------
编译这个DLL后,再新建一个程序调用这个DLL的InstallHook并传入目标进程的主窗口句柄就可:
unit
fmMain;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls,
Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
Button2:
TButton;
Edit1: TEdit;
procedure Button1Click(Sender:
TObject);
procedure Button2Click(Sender: TObject);
private
{ Private
declarations }
public
{ Public declarations }
end;
var
Form1:
TForm1;
InstallHook: function (SWindow: THandle):Boolean;stdcall;
UnHook:
procedure;stdcall;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
var
ModuleHandle:
THandle;
TmpWndHandle: THandle;
begin
TmpWndHandle :=
0;
TmpWndHandle := FindWindow(nil, ‘‘目标窗口的标题‘‘);
if not
isWindow(TmpWndHandle) then
begin
MessageBox(self.Handle, ‘‘没有找到窗口‘‘,
‘‘!!!‘‘, MB_OK);
exit;
end;
ModuleHandle :=
LoadLibrary(‘‘Hook.dll‘‘);
@InstallHook := GetProcAddress(ModuleHandle,
‘‘InstallHook‘‘);
@UnHook := GetProcAddress(ModuleHandle, ‘‘UnHook‘‘);
if
InstallHook(FindWindow(nil, ‘‘Untitled‘‘)) then
ShowMessage(‘‘Hook
OK‘‘);
end;
procedure TForm1.Button2Click(Sender:
TObject);
begin
UnHook
end;
end.
原文：http://www.cnblogs.com/chenjian/p/3543607.html