NetBSD Security Advisory 2002-027: ftpd STAT output non-conformance can deceive firewall devices

[NetBSD Security Officer <security-officer () netbsd org>]

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                 NetBSD Security Advisory 2002-027
                 =================================

Topic:          ftpd STAT output non-conformance can deceive firewall devices

Version:        NetBSD-current: source prior to Oct 26, 2002
                NetBSD 1.6:     affected
                NetBSD-1.5.3:   affected
                NetBSD-1.5.2:   affected
                NetBSD-1.5.1:   affected
                NetBSD-1.5:     affected

Severity:       Malicious parties can corrupt state tables in
                intermediate firewall devices and trick them into making
                unexpected TCP connections.

Fixed:          NetBSD-current:         Oct 26, 2002
                NetBSD-1.6 branch:      Nov 2, 2002
                NetBSD-1.5 branch:      Oct 26, 2002


Abstract
========

NetBSD's ftpd responds to the STAT command in a way that is not
standards conformant, when a filename that contains "\n[0-9]" is
specified.  This could be used by a malicious party to corrupt state
tables in firewall devices between an FTP client and a NetBSD FTP
server.


Technical Details
=================

According to RFC959 (page 36), if a non-response digit appears in an
FTP control stream, it must be escaped by inserting a space before it.
NetBSD's ftpd did not obey this requirement.

See also: http://www.kb.cert.org/vuls/id/328867


Solutions and Workarounds
=========================

Upgrading libexec/ftpd is required to eliminate this problem.

The following instructions describe how to upgrade your ftpd
binaries by updating your source tree and rebuilding and
installing a new version of ftpd.

* NetBSD-current:

        Systems running NetBSD-current dated from before 2002-10-26
        should be upgraded to NetBSD-current dated 2002-10-26 or later.

        The following directories need to be updated from the
        netbsd-current CVS branch (aka HEAD):
                libexec/ftpd

        To update from CVS, re-build, and re-install ftpd:
                # cd src
                # cvs update -d -P libexec/ftpd
                # cd libexec/ftpd

                # make cleandir dependall
                # make install


* NetBSD 1.6:

        Systems running NetBSD 1.6 sources dated from before 2002-11-02 should
        be upgraded from NetBSD 1.6.* sources dated 2002-11-02 or later.

        The following directories need to be updated from the
        netbsd-1-6 CVS branch:
                libexec/ftpd

        To update from CVS, re-build, and re-install ftpd:

                # cd src
                # cvs update -d -P -r netbsd-1-6 libexec/ftpd
                # cd libexec/ftpd

                # make cleandir dependall
                # make install


* NetBSD 1.5, 1.5.1, 1.5.2, 1.5.3:

        Systems running NetBSD 1.5, 1.5.1, 1.5.2, or 1.5.3 sources dated
        from before 2002-10-26 should be upgraded from NetBSD 1.5.*
        sources dated 2002-10-26 or later.

        The following directories need to be updated from the
        netbsd-1-5 CVS branch:
                libexec/ftpd

        To update from CVS, re-build, and re-install ftpd:

                # cd src
                # cvs update -d -P -r netbsd-1-5 libexec/ftpd
                # cd libexec/ftpd

                # make cleandir dependall
                # make install


Thanks To
=========

Internet Initiative Japan Inc.


Revision History
==============

        2002-11-20      Initial release


More Information
================

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at 
  ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2002-027.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/.


Copyright 2002, The NetBSD Foundation, Inc.  All Rights Reserved.

$NetBSD: NetBSD-SA2002-027.txt,v 1.6 2002/11/19 16:43:05 david Exp $


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