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Category:   Application (File Transfer/Sharing)  >   FTP (Generic) Vendors:   FreeBSD, HPE, NetBSD, OpenBSD, SGI (Silicon Graphics), Sun
(FreeBSD Releases Fix) Re: Several FTP Server Implementations Allow Remote Users to Obtain Root-Level Privileges on the Server
SecurityTracker Alert ID:  1001347
SecurityTracker URL:  http://securitytracker.com/id/1001347
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Apr 18 2001
Impact:   Execution of arbitrary code via local system, Execution of arbitrary code via network, Root access via local system, Root access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   Network Associates COVERT Labs issued an advisory (COVERT-2001-02) for multiple FTP server implementations. These implementations allow remote and local users to obtain root-level privileges on the server.

In general, if the remote user has the ability to create directories on the FTP server, these vulnerabilities can be exploited. The vulnerabilities are related to the use of the glob() function.

In some cases, user input that has been expanded by glob() can exceed expected boundary lengths and trigger a buffer overflow. In other cases, the glob() function contains other buffer overflows.

Network Associates reports that the following operating systems have been confirmed to contain vulnerable FTP daemons:

FreeBSD 4.2, OpenBSD 2.8, NetBSD 1.5, IRIX 6.5.x, HPUX 11, Solaris 8

For details on the exact nature of the vulnerabilities, see the source message or refer to the COVERT Labs Advisory:

http://www.pgp.com/research/covert/advisories/048.asp

Impact:   A remote or local user can obtain root privileges on the FTP server.
Solution:   See the source message for the FreeBSD Advisory describing the solution.
Cause:   Boundary error
Underlying OS:  UNIX (FreeBSD)

Message History:   This archive entry is a follow-up to the message listed below.
Apr 10 2001 Several FTP Server Implementations Allow Remote Users to Obtain Root-Level Privileges on the Server



 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-01:33.ftpd-glob


-----BEGIN PGP SIGNED MESSAGE-----

=============================================================================
FreeBSD-SA-01:33                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          globbing vulnerability in ftpd

Category:       core
Module:         ftpd/libc
Announced:      2001-04-17
Credits:        John McDonald and Anthony Osborne, COVERT Labs
Affects:        FreeBSD 3.x (all releases), FreeBSD 4.x (all releases),
                FreeBSD 3.5-STABLE and 4.3-RC prior to the
                correction date.
Corrected:      2001-04-17 (FreeBSD 4.3-RC)
                2001-04-17 (FreeBSD 3.5-STABLE)
Vendor status:  Corrected
FreeBSD only:   NO

I.   Background

Numerous FTP daemons, including the daemon distributed with FreeBSD,
use server-side globbing to expand pathnames via user input.  This
globbing is performed by FreeBSD's glob() implementation in libc.

II.  Problem Description

The glob() function contains potential buffer overflows that may be
exploitable through the FTP daemon.  If a directory with a name of
a certain length is present, a remote user specifying a pathname
using globbing characters may cause arbitrary code to be executed
on the FTP server as user running ftpd, usually root.

Additionally, when given a path containing numerous globbing
characters, the glob() functions may consume significant system
resources when expanding the path.  This can be controlled by
setting user limits via /etc/login.conf and setting limits on
globbing expansion.

All versions of FreeBSD prior to the correction date, including
FreeBSD 3.5.1 and 4.2 contain this problem.  The base system that
will ship with FreeBSD 4.3 does not contain this problem since it
was corrected before the release.

III. Impact

Remote users may be able to execute arbitrary code on the FTP server
as the user running ftpd, usually root.

The FTP daemon supplied with FreeBSD is enabled by default to allow
access to authorized local users and not anonymous users, thus
limiting the impact to authorized local users.

IV.  Workaround

If the FTP daemon is executed from inetd, disable the FTP daemon by
commenting out the ftp line in /etc/inetd.conf, then reload the
inetd configuration by executing the following command as root:

# killall -HUP inetd

V.   Solution

One of the following:

1) Upgrade to FreeBSD 4.3-RC or 3.5.1-STABLE after the correction
date.

2) Download the patch and detached PGP signature from the following
location:

The following patch applies to FreeBSD 4.x:

# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.4.x.patch
# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.4.x.patch.asc

The following patch applies to FreeBSD 3.x:

# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.3.x.patch
# fetch ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:33/glob.3.x.patch.asc

Verify the detached signature using your PGP utility.

Issue the following commands as root:

# cd /usr/src
# patch -p < /path/to/patch
# cd /usr/src/lib/libc
# make all install
# cd /usr/src/libexec/ftpd
# make all install

If the FTP daemon is running standalone, it will have to be manually
stopped and restarted.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.4 (FreeBSD)
Comment: For info see http://www.gnupg.org

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-----END PGP SIGNATURE-----

 
 


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