旅途

Windows下網(wǎng)絡(luò)數(shù)據(jù)報(bào)的監(jiān)聽和攔截技術(shù)1

        Windows下網(wǎng)絡(luò)數(shù)據(jù)報(bào)的監(jiān)聽和攔截技術(shù)是一個(gè)比較古老的話題，應(yīng)用也很廣泛，例如

防火墻等等。這篇小文只是對(duì)該技術(shù)的一個(gè)總結(jié)，沒有新技術(shù)，高手免看：）

        要監(jiān)聽和攔截Windows下的數(shù)據(jù)報(bào)，基本可以在兩個(gè)層次進(jìn)行，一個(gè)是用戶態(tài)(user-mo

de)，一個(gè)是核心態(tài)(kernel-mode)。

        在用戶態(tài)下，從高到低大概有四種方法。

        1、原是套結(jié)字(Raw Socket)。Winsock2以后提供了原始套結(jié)字功能，可以在用戶態(tài)用

Winsock函數(shù)接收所有流經(jīng)Winsock的IP包。這種方法在MSDN里面有敘述，是MS官方支持

的方法，在網(wǎng)上也有很多資料。但是這種方法只能監(jiān)聽但是不能攔截?cái)?shù)據(jù)報(bào)，所以可以

作為網(wǎng)絡(luò)監(jiān)視器的選擇技術(shù)，但是不能實(shí)現(xiàn)防火墻等更高要求的功能。另外最致命的缺

點(diǎn)就是只能在Winsock層次上進(jìn)行，而對(duì)于網(wǎng)絡(luò)協(xié)議棧中底層協(xié)議的數(shù)據(jù)包例如TDI無法

進(jìn)行處理。對(duì)于一些木馬和病毒來說很容易避開這個(gè)層次的監(jiān)聽。

        2、替換系統(tǒng)自帶的WINSOCK動(dòng)態(tài)連接庫。這種方法可以在很多文章里面找到詳細(xì)的實(shí)現(xiàn)

細(xì)節(jié)。 通過替換系統(tǒng)Winsock庫的部分導(dǎo)出函數(shù)，實(shí)現(xiàn)數(shù)據(jù)報(bào)的監(jiān)聽和攔截。缺點(diǎn)同1。

 

        3、Winsock服務(wù)提供者(SPI)。SPI是Winsock的另一面，是Winsock2的一個(gè)新特性。

起初的Winsock是圍繞著TCP/IP協(xié)議運(yùn)行的，但是在Winsock 2中卻增加了對(duì)更多傳輸協(xié)

議的支持。Winsock2不僅提供了一個(gè)供應(yīng)用程序訪問網(wǎng)絡(luò)服務(wù)的Windows socket應(yīng)用程

序編程接口（API），還包含了由傳輸服務(wù)提供者和名字解析服務(wù)提供者實(shí)現(xiàn)的Winsock

服務(wù)提供者接口（SPI）和ws2_32.dll。 Winsock 2的傳輸服務(wù)提供者是以動(dòng)態(tài)鏈接庫的

形式（DLL）存在的。以下是winsock 2在傳輸服務(wù)提供者上的WOSA（Windows開放服務(wù)結(jié)

構(gòu)）:

----------------------------

|Windows socket 2 應(yīng)用程序|

----------------------------Windows socket 2 API

|       WS2_32.DLL        |

----------------------------Windows socket 2 傳輸SPI

|   傳輸服務(wù)提供者（DLL）  |

----------------------------

Windows socket SPI提供三種協(xié)議：分層協(xié)議，基礎(chǔ)協(xié)議和協(xié)議鏈。分層協(xié)議是在基礎(chǔ)

協(xié)議的上層，依靠底層基礎(chǔ)協(xié)議實(shí)現(xiàn)更高級(jí)的通信服務(wù)。基礎(chǔ)協(xié)議是能夠獨(dú)立，安全地

和遠(yuǎn)程端點(diǎn)實(shí)現(xiàn)數(shù)據(jù)通信的協(xié)議，它是相對(duì)與分層協(xié)議而言的。協(xié)議鏈?zhǔn)菍⒁幌盗械幕?/p>

礎(chǔ)協(xié)議和分層協(xié)議按特點(diǎn)的順序連接在一起的鏈狀結(jié)構(gòu)，可以通過Platform SDK附帶的

工具Sporder.exe察看系統(tǒng)已經(jīng)安裝的SPI，請(qǐng)參見下圖：

API------------------------

   |      WS2_32.DLL     |

SPI------------------------

   | 分層協(xié)議 |

SPI-------------

   | 分層協(xié)議 |

SPI------------------------

   |       基礎(chǔ)協(xié)議       |

   ------------------------

        每個(gè)應(yīng)用程序通過Ws2_32.dll和相應(yīng)的服務(wù)提供者進(jìn)行嚴(yán)格的數(shù)據(jù)交換。Ws2_32.dl

l根

據(jù)應(yīng)用程序在創(chuàng)建套接字時(shí)所提供的參數(shù)來選擇特定的服務(wù)提供者，然后把應(yīng)用程序的

實(shí)現(xiàn)過程轉(zhuǎn)發(fā)由所選創(chuàng)建套接字的服務(wù)提供者來管理。也就是說，Ws2_32.dll只是一個(gè)

中間過程，而應(yīng)用程序只是一個(gè)接口，數(shù)據(jù)通信的實(shí)現(xiàn)卻是由服務(wù)提供者來完成的。所

以我們通過適當(dāng)?shù)脑黾幼约旱姆謱訁f(xié)議服務(wù)提供者，使其位于SPI的頂端，那么就能將W

s2_32.dll傳給服務(wù)提供者的數(shù)據(jù)報(bào)攔截下來。由于是MS的官方方法，具體的使用方法在

其Platform SDK里面有詳細(xì)的例子(LSP)，在MSDN里面也有詳細(xì)的解釋。這種方法的優(yōu)點(diǎn)

是能夠獲得調(diào)用Winsock的進(jìn)程的詳細(xì)信息，并能實(shí)現(xiàn)Qos和數(shù)據(jù)加密。所以SPI是用戶態(tài)

數(shù)據(jù)攔截的較好地點(diǎn)。缺點(diǎn)同1。

        4、Windows2000包過濾接口。由于過濾規(guī)則限制太多不靈活而應(yīng)用不多。

        5、網(wǎng)絡(luò)監(jiān)視器SDK。MS官方的實(shí)時(shí)監(jiān)視分析網(wǎng)絡(luò)數(shù)據(jù)的方法。但是由于封裝的太復(fù)?

櫻?

使用起來不靈活。

 

        在核心態(tài)下，數(shù)據(jù)報(bào)的監(jiān)視和攔截方法比較復(fù)雜，由于大多個(gè)人防火墻都是在核心?

?

實(shí)現(xiàn)的，所以在這里比較詳細(xì)的敘述一下。具體的請(qǐng)參見nt/2kDDK文檔。大概有下面幾

個(gè)方法。

1、     TDI過濾驅(qū)動(dòng)程序（TDI Filter Driver）。

2、     NDIS中間層驅(qū)動(dòng)程序（NDIS Intermediate Driver）。編寫IM DRIVER在NDIS中間層

 

 

對(duì)MINIPORT（網(wǎng)卡驅(qū)動(dòng)程序）和協(xié)議驅(qū)動(dòng)程序之間的數(shù)據(jù)包進(jìn)行攔截。這是微軟提供的

一種技術(shù)。在DDK中MS提供了Passthru例子，很多中間層過濾驅(qū)動(dòng)都可以由之改編。但編

寫該過濾程序攔截程序非常的復(fù)雜，安裝也很麻煩。

3、     Win2k Filter-Hook Driver。

4、     NDIS Hook Driver。這種方法又有兩種實(shí)現(xiàn)方式。

（1）向NDIS注冊(cè)假協(xié)議（fake protocol）。這是在協(xié)議層上的處理。在Windows內(nèi)核中

，所有已注冊(cè)的協(xié)議是通過一個(gè)單向的協(xié)議鏈表來維護(hù)的。這個(gè)單向鏈表保存了所有已

注冊(cè)協(xié)議的NDIS_PROTOCOL_BLOCK結(jié)構(gòu)的地址，在這個(gè)結(jié)構(gòu)中保存了協(xié)議驅(qū)動(dòng)所指定的相

應(yīng)的派發(fā)函數(shù)的地址如RECEIVE_HANDLER等。

struct _NDIS_PROTOCOL_BLOCK

{

PNDIS_OPEN_BLOCK OpenQueue; // queue of opens for this protocol

REFERENCE Ref; // contains spinlock for OpenQueue

UINT Length; // of this NDIS_PROTOCOL_BLOCK struct

NDIS50_PROTOCOL_CHARACTERISTICS ProtocolCharacteristics;// handler addresses

 

struct _NDIS_PROTOCOL_BLOCK * NextProtocol; // Link to next

ULONG MaxPatternSize;

#if defined(NDIS_WRAPPER)

//

// Protocol filters

//

struct _NDIS_PROTOCOL_FILTER * ProtocolFilter[NdisMediumMax+1];

WORK_QUEUE_ITEM WorkItem; // Used during NdisRegisterProtocol to

// notify protocols of existing drivers.

KMUTEX Mutex; // For serialization of Bind/Unbind requests

PKEVENT DeregEvent; // Used by NdisDeregisterProtocol

#endif

};

typedef struct _NDIS_PROTOCOL_BLOCK NDIS_PROTOCOL_BLOCK, *PNDIS_PROTOCOL_BLO

CK;并且，每個(gè)協(xié)議驅(qū)動(dòng)還對(duì)應(yīng)一個(gè)NDIS_OPEN_BLOCK的單向鏈表來維護(hù)其所綁定的網(wǎng)卡

信息。當(dāng)協(xié)議驅(qū)動(dòng)調(diào)用NdisRegisterProtocol之后，

EXPORT

VOID

NdisRegisterProtocol(

OUT PNDIS_STATUS Status,

OUT PNDIS_PROTOCOL_BLOCK NdisProtocolHandle, /*注意NDIS_HANDLE所指向的就是PN

DIS_PROTOCOL_BLOCK的結(jié)構(gòu)，不要有什么懷疑。*/

IN PNDIS_PROTOCOL_CHARACTERISTICS ProtocolCharacteristics,

IN UINT CharacteristicsLength

);

NDIS總是會(huì)把新注冊(cè)的協(xié)議放在協(xié)議鏈表的表頭并返回這張表，所以只要我們注冊(cè)一個(gè)

新的協(xié)議通過新協(xié)議注冊(cè)返回的鏈表頭就可以輕而易舉的遍歷系統(tǒng)中所有協(xié)議表。但是

，如果要成功地掛接派發(fā)函數(shù)，還需要對(duì)協(xié)議所對(duì)應(yīng)的NDIS_OPEN_BLOCK結(jié)構(gòu)里的派發(fā)函

數(shù)進(jìn)行掛接，因?yàn)镹DIS并不是直接調(diào)用協(xié)議驅(qū)動(dòng)在NDIS_PROTOCOL_CHARACTERISTICS所注

冊(cè)的派發(fā)函數(shù)地址，而是調(diào)用NDIS_OPEN_BLOCK里的派發(fā)函數(shù)。

struct _NDIS_OPEN_BLOCK

{

PNDIS_MAC_BLOCK MacHandle; // pointer to our MAC

NDIS_HANDLE MacBindingHandle; // context when calling MacXX funcs

PNDIS_ADAPTER_BLOCK AdapterHandle; // pointer to our adapter

PNDIS_PROTOCOL_BLOCK ProtocolHandle; // pointer to our protocol

NDIS_HANDLE ProtocolBindingContext;// context when calling ProtXX funcs

PNDIS_OPEN_BLOCK AdapterNextOpen; // used by adapter's OpenQueue

PNDIS_OPEN_BLOCK ProtocolNextOpen; // used by protocol's OpenQueue

PFILE_OBJECT FileObject; // created by operating system

BOOLEAN Closing; // TRUE when removing this struct

BOOLEAN Unloading; // TRUE when processing unload

BOOLEAN NoProtRsvdOnRcvPkt; // Reflect the protocol_options

NDIS_HANDLE CloseRequestHandle; // 0 indicates an internal close

KSPIN_LOCK SpinLock; // guards Closing

PNDIS_OPEN_BLOCK NextGlobalOpen;

//

// These are optimizations for getting to MAC routines. They are not

// necessary, but are here to save a dereference through the MAC block.

//

SEND_HANDLER SendHandler;

TRANSFER_DATA_HANDLER TransferDataHandler;

//

// These are optimizations for getting to PROTOCOL routines. They are not

// necessary, but are here to save a dereference through the PROTOCOL block.

 

//

SEND_COMPLETE_HANDLER SendCompleteHandler;

TRANSFER_DATA_COMPLETE_HANDLER TransferDataCompleteHandler;

RECEIVE_HANDLER ReceiveHandler;

RECEIVE_COMPLETE_HANDLER ReceiveCompleteHandler;

//

// Extentions to the OPEN_BLOCK since Product 1.

//

RECEIVE_HANDLER PostNt31ReceiveHandler;

RECEIVE_COMPLETE_HANDLER PostNt31ReceiveCompleteHandler;

//

// NDIS 4.0 extensions

//

RECEIVE_PACKET_HANDLER ReceivePacketHandler;

SEND_PACKETS_HANDLER SendPacketsHandler;

//

// More NDIS 3.0 Cached Handlers

//

RESET_HANDLER ResetHandler;

REQUEST_HANDLER RequestHandler;

//

// Needed for PnP

//

UNICODE_STRING AdapterName; // Upcased name of the adapter we are bound to

};

這張表是一個(gè)單向鏈接表，并且存放了和PNDIS_OPEN_BLOCK->ProtocolCharacteristic

s

一樣的數(shù)據(jù)收發(fā)派發(fā)函數(shù)，當(dāng)?shù)贜塊網(wǎng)卡發(fā)送數(shù)據(jù)包到第N個(gè)協(xié)議時(shí)，就會(huì)調(diào)用第N個(gè)協(xié)議

與第N個(gè)網(wǎng)卡之間建立的

NDIS_OPEN_BLOCK表里的SendHandler或SendPacketHandler。所以我們還需要對(duì)這張表里

的派發(fā)函數(shù)進(jìn)行處理（勾掛）。

值得注意的是，在Windows9x/Me/NT的DDK中，NDIS_PROTOCOL_BLOCK的定義是很明確的，

而在Windows 2000/xp的DDK中，并沒有該結(jié)構(gòu)的詳細(xì)定義，也就是說該結(jié)構(gòu)在Windows2

000/xp下是非公開的，因此開發(fā)人員需要利用各種調(diào)試工具來發(fā)掘該結(jié)構(gòu)的詳細(xì)定義。

也正是因?yàn)槿绱耍@種方法對(duì)平臺(tái)的依賴性比較大，需要在程序中判斷不同的操作系統(tǒng)

版本而使用不同的結(jié)構(gòu)定義。可以用NdisOpenProtocolConfiguration打開協(xié)議配置，用

NdisReadConfiguration查詢NDIS版本。

下面的函數(shù)注冊(cè)fake protocol并將PNDIS_PROTOCOL_BLOCK結(jié)構(gòu)存在ProtHandle中NDIS_

HANDLE GetProtocolBlock()

{

        NDIS_PROTOCOL_CHARACTERISTICS   PChars;

        NDIS_STRING                                             Name;

        NDIS_HANDLE                                             ProtHandle;

        NDIS_STATUS                                             Status;

        NdisZeroMemory(&PChars, sizeof(NDIS_PROTOCOL_CHARACTERISTICS));

        PChars.MajorNdisVersion = 5;

        PChars.MinorNdisVersion = 0;

        NdisInitUnicodeString(&Name, L"WssFW"); // Protocol name

        PChars.Name = Name;

        PChars.OpenAdapterCompleteHandler = NULL;

        PChars.CloseAdapterCompleteHandler = NULL;

        PChars.SendCompleteHandler = NULL;

        PChars.TransferDataCompleteHandler = NULL;

 

        PChars.ResetCompleteHandler = NULL;

        PChars.RequestCompleteHandler = NULL;

        PChars.ReceiveHandler = NULL;

        PChars.ReceiveCompleteHandler = NULL;

        PChars.StatusHandler = NULL;

        PChars.StatusCompleteHandler = NULL;

        PChars.BindAdapterHandler = NULL;

        PChars.UnbindAdapterHandler = NULL;

        PChars.UnloadHandler = NULL;

        PChars.ReceivePacketHandler = NULL;

        PChars.PnPEventHandler= NULL;

        NdisRegisterProtocol(&Status,

                                                 &ProtHandle,

                                                 &PChars,

                                                 sizeof(NDIS_PROTOCOL_CHARACTERIS

TICS));

        ASSERT(Status == NDIS_STATUS_SUCCESS);

        if(Status == NDIS_STATUS_SUCCESS)

                return ProtHandle;

        else

                return NULL;

}

        下面的函數(shù)掛接PNDIS_PROTOCOL_BLOCK中PNDIS_PROTOCOL_CHARACTERISTICS結(jié)構(gòu)的R

ec

eiveHandler和ReceivePacketHandler

PVOID

HookProtoFunc(

                          PNDIS_PROTOCOL_CHARACTERISTICS pCharacteristics,

                          DWORD dwFunctionCode,

                          PVOID pfuncNew,

                          DWORD dwNdisVersion)

{

        PVOID pOldFunc = NULL;

        //Check parameters

        if( (!pCharacteristics ) || (!pfuncNew) )

                return NULL;

        switch(dwFunctionCode)

        {

        case PROTO_RECEIVE_HANDLER:

                //Just hook once!

                if(pCharacteristics->ReceiveHandler != pfuncNew )

                {

                        pOldFunc = pCharacteristics->ReceiveHandler;

                        if( pOldFunc )

                                pCharacteristics->ReceiveHandler = pfuncNew;

                }

                break;

        case PROTO_RECEIVE_PACKET_HANDLER:

                if(pCharacteristics->ReceivePacketHandler != pfuncNew)

                {

                        //if pOpenBlock is NULL or pOpenBlock->ReceivePacketHandl

er is NULL,

                        //just hook Characteristics;

                        pOldFunc = pCharacteristics->ReceivePacketHandler;

                        if(pOldFunc)

                                pCharacteristics->ReceivePacketHandler = pfuncNew

;

                }

                break;

        default:

                break;

        }

        return pOldFunc;

}

下面的函數(shù)掛接PNDIS_OPEN_BLOCK結(jié)構(gòu)里的ReceiveHandler和ReceivePacketHandler

PVOID

HookBlockFunc(

                          PNDIS_OPEN_BLOCK pFirstOpenBlock,

                          DWORD dwFunctionCode,

                          PVOID pfuncNew,

                          DWORD dwNdisVersion)

{

        RECEIVE_HANDLER * pReceiveHandler = NULL;

        RECEIVE_PACKET_HANDLER * pReceivePacketHandler = NULL;

//      PVOID pFuncHandler = NULL;

        PVOID pOldFunc = NULL;

        PNDIS_OPEN_BLOCK pOpenBlock = pFirstOpenBlock;

        if(!pFirstOpenBlock)

                return NULL;

        if(!pfuncNew )

                return NULL;

        switch(dwFunctionCode)

        {

        case PROTO_RECEIVE_HANDLER:

                //travel all NDIS_OPEN_BLOCK

                for(;pOpenBlock;pOpenBlock = GetNextBlock( pOpenBlock,dwNdisVersi

on ))

                {

                        pReceiveHandler = GetReceiveHandler(pOpenBlock,dwNdisVers

ion);

                        //Just hook once!

                        if( *pReceiveHandler != pfuncNew )

                        {

                                pOldFunc = *pReceiveHandler;

                                *pReceiveHandler = pfuncNew;

                        }

                        if(dwNdisVersion == 0x00040001)//win2k ????

                        {

                                pReceiveHandler = GetPostNt31ReceiveHandler(pOpen

Block,dwNdisVersion);

                                if( *pReceiveHandler != pfuncNew )

                                {

                                        pOldFunc = *pReceiveHandler;

                                        *pReceiveHandler = pfuncNew;

                                }

                        }

                }

                break;

        case PROTO_RECEIVE_PACKET_HANDLER:

                //travel all NDIS_OPEN_BLOCK

                for(;pOpenBlock;pOpenBlock = GetNextBlock( pOpenBlock,dwNdisVersi

on ))

                        pReceivePacketHandler = GetReceivePacketHandler( pOpenBlo

ck,dwNdisVersion

 );

                        //Just hook once !

                        if(*pReceivePacketHandler != pfuncNew)

                        {

                                pOldFunc = *pReceivePacketHandler;

                                *pReceivePacketHandler = pfuncNew;

                        }

                }

                break;

 

        default:

                break;

        }

        return pOldFunc;

}