拦截其它程序的网络数据封包

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.