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Cisco Security Advisory: Cisco Security Agent for Linux Port Scan
Denial of Service

Advisory ID: cisco-sa-20061025-csa

http://www.cisco.com/warp/public/707/cisco-sa-20061025-csa.shtml

Revision 1.0

For Public Release 2006 October 25 1600 UTC (GMT)

+---------------------------------------------------------------------

Summary
=======

Cisco Security Agent (CSA) for Linux contains a denial of service
vulnerability involving port scans. By performing a port scan against
a system running a vulnerable version of CSA, it is possible to cause
the system to become unresponsive. Cisco Unified CallManager (CUCM)
and Cisco Unified Presence Server (CUPS) ship with a vulnerable CSA
version.

There are workarounds for this vulnerability. Cisco has made free
software available to address this vulnerability for affected
customers.

This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20061025-csa.shtml

Affected Products
=================

Vulnerable Products
+------------------

The following CSA versions are vulnerable to the port scanning issue:

  * CSA version 4.5 for Linux (standalone and managed) prior to
    Hotfix 4.5.1.657
  * CSA version 5.0 for Linux (standalone and managed) prior to
    Hotfix 5.0.0.193

The following Cisco products include a standalone CSA for Linux
version which are also vulnerable to this issue:

  * Cisco Unified CallManager (CUCM) 5.0 versions including 5.0(4)
  * Cisco Unified Presence Server (CUPS) 1.0 versions including 1.0(2)

Products Confirmed Not Vulnerable
+--------------------------------

The following CSA Agent versions are not vulnerable to the port
scanning issue:

  * CSA version 5.1 (standalone and managed) for Linux
  * All CSA versions (standalone and managed) for Windows
  * All CSA versions (standalone and managed) for Solaris

No other Cisco products are currently known to be affected by this
vulnerability.

Details
=======

Cisco Security Agent (CSA) provides threat protection for server and
desktop computing systems. CSA for Linux is vulnerable to a denial of
service attack that may be triggered during the identification of
network port scans. By running a port scan with specific options, it
is possible to cause excessive system resource consumption resulting
in a denial of service. It is possible to mitigate this vulnerability
by restricting network access to vulnerable systems to trusted
networks. This issue is not a Linux operating system issue. CSA
versions for other operating systems (Windows, Solaris) are not
affected by this vulnerability. This issue is documented in Cisco Bug
ID CSCse98684.

Cisco Unified CallManager 5.0 versions, including 5.0(4), ship with a
vulnerable version of CSA. A new CallManager Options Package (COP)
file is available to update the CSA version on CallManager 5.0(4).
Future versions of CallManager will include the updated CSA version.
This issue is documented in Cisco Bug ID CSCse97601.

Cisco Unified Presence Server 1.0 versions, including 1.0(2), ship
with a vulnerable version of CSA. A new COP file is available to
update the CSA version on CUPS 1.0(2). Future versions of CUPS will
include the updated CSA version. This issue is documented in Cisco
Bug ID CSCsg40052.

Impact
======

Successful exploitation of the port scan vulnerability against a
Linux system running a vulnerable version of CSA may cause the system
to become unresponsive due to resource exhaustion while a port scan
is underway. This may result in the failure of critical processes and
remote network connectivity. Repeated port scans may result in a
prolonged denial of service. If a CUCM or CUPS system running a
vulnerable CSA version is scanned, voice operations may become
unavailable for the duration of the port scan.

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.

CSA for Linux
+------------

+---------------------------------------+
|  Affected Software  | Fixed Software  |
|       Version       |     Version     |
|---------------------+-----------------|
| CSA Hotfix prior to | CSA Hotfix      |
| 4.5.1.657           | 4.5.1.657       |
|---------------------+-----------------|
| CSA Hotfix prior to | CSA Hotfix      |
| 5.0.0.193           | 5.0.0.194 *     |
+---------------------------------------+

* CSA Hotfix 5.0.0.194 deprecates CSA Hotfix 5.0.0.193.

Fixed CSA software can be downloaded at
http://www.cisco.com/cgi-bin/tablebuild.pl/csahf-crypto?psrtdcat20e2

CUCM/CUPS
+--------

+---------------------------------------+
| Affected Software |  Fixed Software   |
|      Version      |      Version      |
|-------------------+-------------------|
| CUCM 5.0 version  | CUCM 5.0(4) with  |
| including 5.0(4)  | CSA COP upgrade   |
|-------------------+-------------------|
| CUPS 1.0 version  | CUPS 1.0(2) with  |
| including 1.0(2)  | CSA COP upgrade   |
+---------------------------------------+

The CUCM COP file (platform-csa-4.5.1-657.1.cop.sgn) and installation
instructions can be downloaded at
http://www.cisco.com/cgi-bin/tablebuild.pl/cmva-3des?psrtdcat20e2

The CUPS COP file (CUPS-1.0.2-CSA-4.5.1-657.1.i386.cop.sgn) and
installation instructions can be downloaded at
http://www.cisco.com/cgi-bin/tablebuild.pl/cups-10?psrtdcat20e2

Workarounds
===========

It is possible to workaround the Linux port scan vulnerability by
disabling the Netshield rule in managed agents via the CSA Management
Center (CSAMC) console (not possible for standalone and CUCM/CUPS
agents). Administrators should exercise caution when employing this
workaround because it may open a system to additional network denial
of service attacks. With the Netshield rule disabled, CSA will still
provide protection against buffer overflows and other malicious
activities.

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-alert@cisco.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: tac@cisco.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 not aware of any public announcements or malicious
use of the vulnerabilities described in this advisory.

This vulnerability was discovered internally by Cisco.

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-20061025-csa.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-announce@cisco.com
  * first-teams@first.org
  * bugtraq@securityfocus.com
  * vulnwatch@vulnwatch.org
  * cisco@spot.colorado.edu
  * cisco-nsp@puck.nether.net
  * full-disclosure@lists.grok.org.uk
  * comp.dcom.sys.cisco@newsgate.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-October-25 | 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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