Re: [FW1] CERT Advisory CA-2001-17

["Tim Holman" <tholman@FW1-NOSPAMuk.didata.com>]

You're right - if it's off, then this is not an issue, and if you're using a
basic standalone installation, you don't need control connections.  Be
careful though, as 'control connections' also includes rules neccessary for
authentication and VPNs to work properly.
All the Check Point fix does is disable the Any Any RDP rule by default, so
it's no longer there in the rulebase.
If at a later stage you need RDP back, you must explicitly define it, and
again are vulnerable to this risk, UNLESS you make sure you put in specific
source / destination hosts for this traffic and ensure those hosts are not
vulnerable to any RDP specific problems.
This vulnerability also highlights the rest of the implied rules.  If you
don't need them, disable them.  As you can't disable them individually,
disable implied rules and put the ones you need back in.  It's only a matter
of time until hacks are found for the other implied rules that you don't
necessarily need anyway !

Tim


----- Original Message -----
From: "Robert C. Wessel" <rwessel@cfsoft.com>
To: "Oscar Aviles" <oaviles@cosapisoft.com.pe>;
<fw-1-mailinglist@beethoven.us.checkpoint.com>
Sent: Tuesday, July 10, 2001 11:26 AM
Subject: Re: [FW1] CERT Advisory CA-2001-17


>
> If "Accept FIrewall-1 Control Connections" is "off" on a limited user
count
> FW1, is this still an issue?
>
> -Robert
>
> At 07:34 PM 7/9/01 -0500, Oscar Aviles wrote:
> >
> >
> >
> >       Look that friends....
> >
> >
> >
> >
> >
> >-----BEGIN PGP SIGNED MESSAGE-----
> >
> >CERT Advisory CA-2001-17 Check Point RDP Bypass Vulnerability
> >
> >   Original release date: July 09, 2001
> >   Last revised: --
> >   Source: CERT/CC
> >
> >   A complete revision history is at the end of this file.
> >
> >Systems Affected
> >
> >     * Check Point VPN-1 and FireWall-1 Version 4.1
> >
> >Overview
> >
> >   A vulnerability in Check Point FireWall-1 and VPN-1 may allow an
> >   intruder to pass traffic through the firewall on port 259/UDP.
> >
> >I. Description
> >
> >   Inside Security GmbH has discovered a vulnerability in Check Point
> >   FireWall-1 and VPN-1 that allows an intruder to bypass the firewall.
> >   The default FireWall-1 management rules allow arbitrary RDP (Reliable
> >   Data Protocol) connections to traverse the firewall. RFC-908 and
> >   RFC-1151 describe the Reliable Data Protocol (RDP). Quoting from
> >   RFC-908:
> >
> >     The Reliable Data Protocol (RDP) is designed to provide a reliable
> >     data transport service for packet-based applications such as remote
> >     loading and debugging.
> >
> >   RDP was designed to have much of the same functionality as TCP, but it
> >   has some advantages over TCP in certain situations. FireWall-1 and
> >   VPN-1 include support for RDP, but they do not provide adequate
> >   security controls. Quoting from the advisory provided by Inside
> >   Security GmbH:
> >
> >     By adding a faked RDP header to normal UDP traffic any content can
> >     be passed to port 259 on any remote host on either side of the
> >     firewall.
> >
> >   For more information, see the Inside Security GmbH security advisory,
> >   available at
> >
> >          http://www.inside-security.de/advisories/fw1_rdp.html
> >
> >   Although the CERT/CC has not seen any incident activity related to
> >   this vulnerability, we do recommend that all affected sites upgrade
> >   their Check Point software as soon as possible.
> >
> >II. Impact
> >
> >   An intruder can pass UDP traffic with arbitrary content through the
> >   firewall on port 259 in violation of implied security policies.
> >
> >   If an intruder can gain control of a host inside the firewall, he may
> >   be able to use this vulnerability to tunnel arbitrary traffic across
> >   the firewall boundary.
> >
> >   Additionally, even if an intruder does not have control of a host
> >   inside the firewall, he may be able to use this vulnerability as a
> >   means of exploiting another vulnerability in software listening
> >   passively on the internal network.
> >
> >   Finally, an intruder may be able to use this vulnerability to launch
> >   certain kinds of denial-of-service attacks.
> >
> >III. Solutions
> >
> >   Install a patch from Check Point Software Technologies. More
> >   information is available in Appendix A.
> >
> >   Until a patch can be applied, you may be able to reduce your exposure
> >   to this vulnerability by configuring your router to block access to
> >   259/UDP at your network perimeter.
> >
> >Appendix A
> >
> >Check Point
> >
> >   Check Point has issued an alert for this vulnerability at
> >
> >          http://www.checkpoint.com/techsupport/alerts/
> >
> >   Download the patch from Check Point's web site:
> >
> >          http://www.checkpoint.com/techsupport/downloads.html
> >
> >Appendix B. - References
> >
> >    1. http://www.inside-security.de/advisories/fw1_rdp.html
> >    2. http://www.kb.cert.org/vuls/id/310295
> >    3. http://www.ietf.org/rfc/rfc908.txt
> >    4. http://www.ietf.org/rfc/rfc1151.txt
> >     _________________________________________________________________
> >
> >   Our thanks to Inside Security GmbH for the information contained in
> >   their advisory.
> >     _________________________________________________________________
> >
> >   This document was written by Ian A. Finlay. If you have feedback
> >   concerning this document, please send email to:
> >
> >          mailto:cert@cert.org?Subject=Feedback CA-2001-17 [VU#310295]
> >
> >   Copyright 2001 Carnegie Mellon University.
> >
> >   Revision History
> >July 09, 2001: Initial Release
> >
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> >
> >
> >
> >
>
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