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Cisco Security Advisory: AVS TCP Relay Vulnerability
Advisory ID: cisco-sa-20060510-avs
http://www.cisco.com/warp/public/707/cisco-sa-20
060510-avs.shtml
Revision 1.0
For Public Release 2006 May 10 1600 UTC (GMT)
+-----------------------------------------------------------
---------
Contents
========
Summary
Affected Products
Details
Impact
Software Version and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of this Notice: FINAL
Distribution
Revision History
Cisco Security Procedures
+-----------------------------------------------------------
---------
Summary
=======
Cisco Application Velocity System's (AVS) default
configuration
allows transparent relay of TCP connections to any reachable
destination TCP port if the receiving TCP service can
process
requests embedded in a HTTP POST method message. This issue
does not
require a software upgrade and can be mitigated by a
configuration
command for all affected customers.
Fixed versions of the AVS software have been modified to
provide a
more secure default configuration.
Cisco has made free software available to address this
vulnerability
for affected customers installing new AVS Devices. The
available
workaround must be manually configured to mitigate the
impact of this
vulnerability for existing AVS devices even if upgrading to
a fixed
version of software.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20
060510-avs.shtml
Affected Products
=================
AVS 3110 and 3120 Application Velocity Systems running all
software
versions prior to 5.0.1 are affected.
Vulnerable Products
+------------------
* AVS 3110 4.0 and 5.0
* AVS 3120 5.0.0
as well as all prior versions for both devices.
Products Confirmed Not Vulnerable
+--------------------------------
The AVS 3180 Management Station is not affected by this
vulnerability.
No other Cisco products are currently known to be affected
by this
vulnerability.
Details
=======
The Cisco AVS 3100 series Application Velocity System is an
enterprise appliance for improving application performance.
Using the
Application Velocity System, web applications deployed
across the WAN
can offer response times typically expected from LAN
environments.
By default, the AVS is normally deployed as a transparent
proxy. The
transparent proxy feature may be exploited to open a TCP
connection
to any reachable destination TCP port and hide the true IP
source
address of the connection TCP port, if the receiving service
can
process requests embedded in a HTTP POST method message.
This issue has been resolved by changing the default
behavior such
that connections are limited based on the destination port
numbers
and connections to TCP ports other than 80 and 443 are
denied.
This issue is documented by the following Cisco bug ID:
* CSCsd32143 (registered customers only)
Note: The available workaround must be manually configured
to
mitigate the impact of this vulnerability for existing AVS
devices
even if upgrading to a fixed version of software.
Impact
======
The AVS may be used to forward unexpected traffic and to
obscure the
true originator of undesirable traffic.
Software Version and Fixes
==========================
When considering software upgrades, also consult
http://www.cisco.com/go
/psirt and any subsequent advisories to
determine exposure and a complete upgrade solution.
In all cases, customers should exercise caution to be
certain the
devices to be upgraded contain sufficient memory and that
current
hardware and software configurations will continue to be
supported
properly by the new release. If the information is not
clear, contact
the Cisco Technical Assistance Center ("TAC") or
your contracted
maintenance provider for assistance.
This issue is fixed for new installations in AVS version
5.0.1 for
both the AVS 3110 and AVS 3120.
Software for AVS 3110 is available at
http://www.cisco.com/cgi-bin/tablebuild.pl/AVS3110-5.0.1
Software for AVS 3120 is available at
http://www.cisco.com/cgi-bin/tablebuild.pl/AVS3120-5.0.1
Note: The available workaround must be manually configured
to
mitigate the impact of this vulnerability for existing AVS
devices
even if upgrading to a fixed version of software.
Workarounds
===========
For existing AVS devices, this issue must be resolved by a
configuration command which blocks the use of redirected
proxy
requests for any TCP ports other than TCP/80 and TCP/443. To
avoid
writing over an existing configuration, this command must be
manually
applied even if software is upgraded to a fixed version. The
configuration commands below should be added to the
"fgn.conf"
configuration file using the AVS Management Console.
<DestinationMapping>
Name default:80 -> default:80
Name default:443 -> default:443
Name default -> localhost:9
</DestinationMapping>
With this Destination map, only TCP connections to ports 80
and 443
will be forwarded. The AVS will reset connections destined
to any
other ports. If HTTP connections must be completed to other
TCP
ports, they must also be added to the configuration element
using the
same syntax as shown above. If destinations are already set
in the
configuration element, only the
Name default -> localhost:9
configuration line needs to be added as the last line in the
Destination map. Adding this line before other lines in the
Destination map may block legitimate traffic. After updating
the
Destination map element, the configuration changes must be
published.
For information on using the AVS Management Console refer
to:
http://ww
w.cisco.com/en/US/products/ps6492/
products_user_guide_chapter09186a008059be02.html
For information about the fgn.conf file refer to:
http://ww
w.cisco.com/en/US/products/ps6492/
products_user_guide_chapter09186a008059bddb.html#wp1045951
For information about Destination Mapping refer to:
http://ww
w.cisco.com/en/US/products/ps6492/
products_user_guide_chapter09186a008059bddb.html#wp1045807
Obtaining Fixed Software
========================
Cisco will make free software available to address this
vulnerability
for affected customers. This advisory will be updated as
fixed
software becomes available. Prior to deploying software,
customers
should consult their maintenance provider or check the
software for
feature set compatibility and known issues specific to their
environment.
Customers may only install and expect support for the
feature sets
they have purchased. By installing, downloading, accessing
or
otherwise using such software upgrades, customers agree to
be bound
by the terms of Cisco's software license terms found at
http://www.cisco.com/public/sw-license-agreement.html ,
or as
otherwise set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml .
Do not contact either "psirt cisco.com" or
"security-alertcisco.com"
for software upgrades.
Customers with Service Contracts
+-------------------------------
Customers with contracts should obtain upgraded software
through
their regular update channels. For most customers, this
means that
upgrades should be obtained through the Software Center on
Cisco's
worldwide website at http://www.cisco.com .
Customers using Third Party Support Organizations
+------------------------------------------------
Customers whose Cisco products are provided or maintained
through
prior or existing agreement with third-party support
organizations
such as Cisco Partners, authorized resellers, or service
providers
should contact that support organization for guidance and
assistance
with the appropriate course of action in regards to this
advisory.
The effectiveness of any workaround or fix is dependent on
specific
customer situations such as product mix, network topology,
traffic
behavior, and organizational mission. Due to the variety of
affected
products and releases, customers should consult with their
service
provider or support organization to ensure any applied
workaround or
fix is the most appropriate for use in the intended network
before it
is deployed.
Customers without Service Contracts
+----------------------------------
Customers who purchase direct from Cisco but who do not hold
a Cisco
service contract and customers who purchase through
third-party
vendors but are unsuccessful at obtaining fixed software
through
their point of sale should get their upgrades by contacting
the Cisco
Technical Assistance Center (TAC). TAC contacts are as
follows.
* +1 800 553 2447 (toll free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* e-mail: taccisco.com
Have your product serial number available and give the URL
of this
notice as evidence of your entitlement to a free upgrade.
Free
upgrades for non-contract customers must be requested
through the
TAC.
Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC
.shtml
for additional TAC contact information, including special
localized
telephone numbers and instructions and e-mail addresses for
use in
various languages.
Exploitation and Public Announcements
=====================================
The Cisco PSIRT is aware of an instance in which the AVS has
been
used to transmit unsolicited commercial e-mail and hide the
true
source of the message.
Status of this Notice: FINAL
============================
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS
AND DOES NOT IMPLY ANY
KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF
THE
INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE
DOCUMENT IS
AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR
UPDATE THIS
DOCUMENT AT ANY TIME.
A stand-alone copy or Paraphrase of the text of this
document that
omits the distribution URL in the following section is an
uncontrolled copy, and may lack important information or
contain
factual errors.
Distribution
============
This advisory is posted on Cisco's worldwide website at:
http://www.cisco.com/warp/public/707/cisco-sa-20
060510-avs.shtml
In addition to worldwide web posting, a text version of this
notice
is clear-signed with the Cisco PSIRT PGP key and is posted
to the
following e-mail and Usenet news recipients.
* cust-security-announcecisco.com
* first-teamsfirst.org
* bugtraqsecurityfocus.com
* vulnwatchvulnwatch.org
* ciscospot.colorado.edu
* cisco-nsppuck.nether.net
* full-disclosurelists.grok.org.uk
* comp.dcom.sys.cisconewsgate.cisco.com
Future updates of this advisory, if any, will be placed on
Cisco's
worldwide website, but may or may not be actively announced
on
mailing lists or newsgroups. Users concerned about this
problem are
encouraged to check the above URL for any updates.
Revision History
================
+---------------------------------------+
| Revision | | Initial |
| 1.0 | 2006-May-10 | public |
| | | release. |
+---------------------------------------+
Cisco Security Procedures
=========================
Complete information on reporting security vulnerabilities
in Cisco
products, obtaining assistance with security incidents, and
registering to receive security information from Cisco, is
available
on Cisco's worldwide website at
http://www.cisco
.com/en/US/products/
products_security_vulnerability_policy.html .
This includes instructions for press inquiries regarding
Cisco
security notices. All Cisco security advisories are
available at
http://www.cisco.com/go
/psirt .
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