Firewall Wizards mailing list archives

NetBSD Security Advisory 2002-024: IPFilter FTP proxy (fwd)


From: Darren Reed <avalon () coombs anu edu au>
Date: Sat, 9 Nov 2002 22:16:01 +1100 (Australia/ACT)

Various people's tried very hard to get me to comment directly on what
is essentially the subject of this email below.  As much as I may have
been able to do that, it is improper of me to do so out of turn and is
better when things such as this go through the correct channels.  If I
do not respect that then it does little to engender further cooperation
and that helps nobody in the long run.

Darren

Forwarded message:
To: bugtraq () securityfocus com
From: NetBSD Security Officer <security-officer () netbsd org>
Organisation: The NetBSD Foundation, Inc.
Reply-To: NetBSD Security Officer <security-officer () netbsd org>
Subject: NetBSD Security Advisory 2002-024: IPFilter FTP proxy
Date: Tue, 05 Nov 2002 08:36:15 +0900
Sender: itojun () itojun org
Message-Id: <20021104233616.F0DE97B9 () starfruit itojun org>
X-OriginalArrivalTime: 03 Nov 2002 23:41:14.0062 (UTC) FILETIME=[7F193EE0:01C28392]
Content-Length: 5398

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               NetBSD Security Advisory 2002-024
               =================================

Topic:                IPFilter FTP proxy

Version:      NetBSD-current: source prior to September 20, 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:     Unexpected TCP session establishment by malicious remote input

Fixed:                NetBSD-current:         September 20, 2002
              NetBSD-1.6 branch:      October 25, 2002
              NetBSD-1.5 branch:      October 19, 2002


Abstract
========

FTP proxy module in IPFilter package may not adequately maintain the
state of FTP commands and responses. As a result, an attacker could
establish arbitrary TCP connections to FTP servers or clients located
behind a vulnerable firewall.


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

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


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

The IPFilter package, which is shipped with NetBSD, prior to 3.4.29
includes the vulnerable FTP proxy module.

Systems enabling both IPFilter and its FTP module are vulnerable.
IPFilter and the FTP proxy module are not enabled by default.
Therefore, the default installation of NetBSD is not vulnerable to
this attack.

Quick workaround:
Disable FTP proxy module in IP NAT configuration file by removing
or commenting out the line which includes both "proxy" and "ftp/".
The default location of the configuration file is /etc/ipnat.conf.

Solution:
Upgrade of the kernel as well as IPFilter-related userland tools.

The following instructions describe how to upgrade your kernel and IPFilter-
related binaries by updating your source tree and rebuilding and
installing a new version.

* NetBSD-current:

      Systems running NetBSD-current dated from before 2002-09-20
      should be upgraded to NetBSD-current dated 2002-09-20 or later.

      The following directories need to be updated from the
      netbsd-current CVS branch (aka HEAD):
              dist/ipf
              regress/sys/kern/ipf
              sys/lkm/netinet/if_ipl
              sys/netinet
              usr.sbin/ipf

      Update the source files:
              # cd src
              # cvs update -d -P dist/ipf
              # cvs update -d -P regress/sys/kern/ipf
              # cvs update -d -P sys/lkm/netinet/if_ipl
              # cvs update -d -P sys/netinet
              # cvs update -d -P usr.sbin/ipf

      Install the updated include files:
              # cd src/sys
              # make includes

      Rebuild the userland tools:
              # cd src/usr.sbin/ipf
              # make cleandir dependall
              # make install

      Rebuild the LKM:
              # cd src/sys/lkm/netinet
              # make cleandir dependall
              # make install

      Rebuild the kernel and reboot:
              # cd src/sys/ARCH/conf
              # config FILENAME
              # cd ../compile/FILENAME
              # make dependall install


* NetBSD 1.6:

      Systems running NetBSD 1.6 dated from before 2002-10-25
      should be upgraded to NetBSD 1.6 dated 2002-10-25 or later.

      The following directories need to be updated from the
      netbsd-1-6 CVS branch:
              dist/ipf
              regress/sys/kern/ipf
              sys/lkm/netinet/if_ipl
              sys/netinet
              usr.sbin/ipf

      Update the source files:
              # cd src
              # cvs update -d -P -r netbsd-1-6 dist/ipf
              # cvs update -d -P -r netbsd-1-6 regress/sys/kern/ipf
              # cvs update -d -P -r netbsd-1-6 sys/lkm/netinet/if_ipl
              # cvs update -d -P -r netbsd-1-6 sys/netinet
              # cvs update -d -P -r netbsd-1-6 usr.sbin/ipf

      Install the updated include files:
              # cd src/sys
              # make includes

      Rebuild the userland tools:
              # cd src/usr.sbin/ipf
              # make cleandir dependall
              # make install

      Rebuild the LKM:
              # cd src/sys/lkm/netinet
              # make cleandir dependall
              # make install

      Rebuild the kernel and reboot:
              # cd src/sys/ARCH/conf
              # config FILENAME
              # cd ../compile/FILENAME
              # make dependall install


* NetBSD 1.5, 1.5.1, 1.5.2, 1.5.3:

      Systems running NetBSD 1.5 dated from before 2002-10-19
      should be upgraded to NetBSD 1.5 dated 2002-10-19 or later.

      The following directories need to be updated from the
      netbsd-1-5 CVS branch:
              dist/ipf
              sys/netinet
              usr.sbin/ipf

      Update the source files:
              # cd src
              # cvs update -d -P -r netbsd-1-5 dist/ipf
              # cvs update -d -P -r netbsd-1-5 usr.sbin/ipf
              # cvs update -d -P -r netbsd-1-5 sys/netinet

      Install the updated include files:
              # cd src/sys
              # make includes

      Rebuild the userland tools:
              # cd src/usr.sbin/ipf
              # make cleandir dependall
              # make install

      Rebuild the LKM:
              # cd src/sys/lkm/netinet
              # make cleandir dependall
              # make install

      Rebuild the kernel and reboot:
              # cd src/sys/ARCH/conf
              # config FILENAME
              # cd ../compile/FILENAME
              # make dependall install


Thanks To
=========

Darren Reed
Martti Kuparinen

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

      2002-11-04      Initial release


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

Advisories may be updated as new information comes to hand.  The most
recent version of this advisory (PGP signed) can be found at 
  ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2002-024.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-SA2002-024.txt,v 1.15 2002/11/04 23:10:47 itojun Exp $


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