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**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:
1 library Hook;
2
3 uses
4 SysUtils,
5 windows,
6 Messages,
7 APIHook in 'APIHook.pas';
8
9 type
10 PData = ^TData;
11 TData = record
12 Hook: THandle;
13 Hooked: Boolean;
14 end;
15
16 var
17 DLLData: PData;
18
19 {------------------------------------}
20 {过程名:HookProc
21 {过程功能:HOOK过程
22 {过程参数:nCode, wParam, lParam消息的相
23 { 关参数
24 {------------------------------------}
25 procedure HookProc(nCode, wParam, lParam: LongWORD);stdcall;
26 begin
27 if not DLLData^.Hooked then
28 begin
29 HookAPI;
30 DLLData^.Hooked := True;
31 end;
32 //调用下一个Hook
33 CallNextHookEx(DLLData^.Hook, nCode, wParam, lParam);
34 end;
35
36
37 {------------------------------------}
38 {函数名:InstallHook
39 {函数功能:在指定窗口上安装HOOK
40 {函数参数:sWindow:要安装HOOK的窗口
41 {返回值:成功返回TRUE,失败返回FALSE
42 {------------------------------------}
43 function InstallHook(SWindow: LongWORD):Boolean;stdcall;
44 var
45 ThreadID: LongWORD;
46 begin
47 Result := False;
48 DLLData^.Hook := 0;
49 ThreadID := GetWindowThreadProcessId(sWindow, nil);
50 //给指定窗口挂上钩子
51 DLLData^.Hook := SetWindowsHookEx(WH_GETMESSAGE, @HookProc, Hinstance, ThreadID);
52 if DLLData^.Hook > 0 then
53 Result := True //是否成功HOOK
54 else
55 exit;
56 end;
57
58 {------------------------------------}
59 {过程名:UnHook
60 {过程功能:卸载HOOK
61 {过程参数:无
62 {------------------------------------}
63 procedure UnHook;stdcall;
64 begin
65 UnHookAPI;
66 //卸载Hook
67 UnhookWindowsHookEx(DLLData^.Hook);
68 end;
69
70 {------------------------------------}
71 {过程名:DLL入口函数
72 {过程功能:进行DLL初始化,释放等
73 {过程参数:DLL状态
74 {------------------------------------}
75 procedure MyDLLHandler(Reason: Integer);
76 var
77 FHandle: LongWORD;
78 begin
79 case Reason of
80 DLL_PROCESS_ATTACH:
81 begin //建立文件映射,以实现DLL中的全局变量
82 FHandle := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, $ffff, 'MYDLLDATA');
83 if FHandle = 0 then
84 if GetLastError = ERROR_ALREADY_EXISTS then
85 begin
86 FHandle := OpenFileMapping(FILE_MAP_ALL_ACCESS, False, 'MYDLLDATA');
87 if FHandle = 0 then Exit;
88 end else Exit;
89 DLLData := MapViewOfFile(FHandle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
90 if DLLData = nil then
91 CloseHandle(FHandle);
92 end;
93 DLL_PROCESS_DETACH:
94 begin
95 if Assigned(DLLData) then
96 begin
97 UnmapViewOfFile(DLLData);
98 DLLData := nil;
99 end;
100 end;
101 end;
102 end;
103
104 {$R *.res}
105 exports
106 InstallHook, UnHook, HookProc;
107
108 begin
109 DLLProc := @MyDLLHandler;
110 MyDLLhandler(DLL_PROCESS_ATTACH);
111 DLLData^.Hooked := False;
112 end.
113
114 ----------------------------------------------------------------------------------------
115 APIHook.Pas的代码:
116
117 unit APIHook;
118
119 interface
120
121 uses
122 SysUtils,
123 Windows, WinSock;
124
125 type
126 //要HOOK的API函数定义
127 TSockProc = function (s: TSocket; var Buf; len, flags: Integer): Integer; stdcall;
128
129 PJmpCode = ^TJmpCode;
130 TJmpCode = packed record
131 JmpCode: BYTE;
132 Address: TSockProc;
133 MovEAX: Array [0..2] of BYTE;
134 end;
135
136 //--------------------函数声明---------------------------
137 procedure HookAPI;
138 procedure UnHookAPI;
139
140 var
141 OldSend, OldRecv: TSockProc; //原来的API地址
142 JmpCode: TJmpCode;
143 OldProc: array [0..1] of TJmpCode;
144 AddSend, AddRecv: pointer; //API地址
145 TmpJmp: TJmpCode;
146 ProcessHandle: THandle;
147 implementation
148
149 {---------------------------------------}
150 {函数功能:Send函数的HOOK
151 {函数参数:同Send
152 {函数返回值:integer
153 {---------------------------------------}
154 function MySend(s: TSocket; var Buf; len, flags: Integer): Integer; stdcall;
155 var
156 dwSize: cardinal;
157 begin
158 //这儿进行发送的数据处理
159 MessageBeep(1000); //简单的响一声
160 //调用直正的Send函数
161 WriteProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize);
162 Result := OldSend(S, Buf, len, flags);
163 JmpCode.Address := @MySend;
164 WriteProcessMemory(ProcessHandle, AddSend, @JmpCode, 8, dwSize);
165 end;
166
167 {---------------------------------------}
168 {函数功能:Recv函数的HOOK
169 {函数参数:同Recv
170 {函数返回值:integer
171 {---------------------------------------}
172 function MyRecv(s: TSocket; var Buf; len, flags: Integer): Integer; stdcall;
173 var
174 dwSize: cardinal;
175 begin
176 //这儿进行接收的数据处理
177 MessageBeep(1000); //简单的响一声
178 //调用直正的Recv函数
179 WriteProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize);
180 Result := OldRecv(S, Buf, len, flags);
181 JmpCode.Address := @MyRecv;
182 WriteProcessMemory(ProcessHandle, AddRecv, @JmpCode, 8, dwSize);
183 end;
184
185 {------------------------------------}
186 {过程功能:HookAPI
187 {过程参数:无
188 {------------------------------------}
189 procedure HookAPI;
190 var
191 DLLModule: THandle;
192 dwSize: cardinal;
193 begin
194 ProcessHandle := GetCurrentProcess;
195 DLLModule := LoadLibrary('ws2_32.dll');
196 AddSend := GetProcAddress(DLLModule, 'send'); //取得API地址
197 AddRecv := GetProcAddress(DLLModule, 'recv');
198 JmpCode.JmpCode := $B8;
199 JmpCode.MovEAX[0] := $FF;
200 JmpCode.MovEAX[1] := $E0;
201 JmpCode.MovEAX[2] := 0;
202 ReadProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize);
203 JmpCode.Address := @MySend;
204 WriteProcessMemory(ProcessHandle, AddSend, @JmpCode, 8, dwSize); //修改Send入口
205 ReadProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize);
206 JmpCode.Address := @MyRecv;
207 WriteProcessMemory(ProcessHandle, AddRecv, @JmpCode, 8, dwSize); //修改Recv入口
208 OldSend := AddSend;
209 OldRecv := AddRecv;
210 end;
211
212 {------------------------------------}
213 {过程功能:取消HOOKAPI
214 {过程参数:无
215 {------------------------------------}
216 procedure UnHookAPI;
217 var
218 dwSize: Cardinal;
219 begin
220 WriteProcessMemory(ProcessHandle, AddSend, @OldProc[0], 8, dwSize);
221 WriteProcessMemory(ProcessHandle, AddRecv, @OldProc[1], 8, dwSize);
222 end;
223
224 end.
225
226 ---------------------------------------------------------------------------------------------
227 编译这个DLL后,再新建一个程序调用这个DLL的InstallHook并传入目标进程的主窗口句柄就可:
228 unit fmMain;
229
230 interface
231
232 uses
233 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
234 Dialogs, StdCtrls;
235
236 type
237 TForm1 = class(TForm)
238 Button1: TButton;
239 Button2: TButton;
240 Edit1: TEdit;
241 procedure Button1Click(Sender: TObject);
242 procedure Button2Click(Sender: TObject);
243 private
244 { Private declarations }
245 public
246 { Public declarations }
247 end;
248
249 var
250 Form1: TForm1;
251 InstallHook: function (SWindow: THandle):Boolean;stdcall;
252 UnHook: procedure;stdcall;
253 implementation
254
255 {$R *.dfm}
256
257 procedure TForm1.Button1Click(Sender: TObject);
258 var
259 ModuleHandle: THandle;
260 TmpWndHandle: THandle;
261 begin
262 TmpWndHandle := 0;
263 TmpWndHandle := FindWindow(nil, '目标窗口的标题');
264 if not isWindow(TmpWndHandle) then
265 begin
266 MessageBox(self.Handle, '没有找到窗口', '!!!', MB_OK);
267 exit;
268 end;
269 ModuleHandle := LoadLibrary('Hook.dll');
270 @InstallHook := GetProcAddress(ModuleHandle, 'InstallHook');
271 @UnHook := GetProcAddress(ModuleHandle, 'UnHook');
272 if InstallHook(FindWindow(nil, 'Untitled')) then
273 ShowMessage('Hook OK');
274 end;
275
276 procedure TForm1.Button2Click(Sender: TObject);
277 begin
278 UnHook
279 end;
280
281 end.
282
原文地址：http://hi.baidu.com/lzj1981/blog/item/e026663325667748ac4b5fe5.html