[c-nsp] Cisco Security Advisory: Multiple Vulnerabilities in the Cisco ACE Application Control Engine Module and Cisco ACE 4710 Application Control Engine

Wed Aug 11 11:30:00 EDT 2010

The Cisco ACE Application Control Engine Module and Cisco ACE 4710
Application Control Engine contain the following DoS vulnerabilities:

  * Real-Time Streaming Protocol (RTSP) inspection DoS vulnerability
  * HTTP, RTSP, and Session Initiation Protocol (SIP) inspection DoS
    vulnerability
  * Secure Socket Layer (SSL) DoS vulnerability
  * SIP inspection DoS vulnerability

Cisco has released free software updates for affected customers.
Workarounds that mitigate some of the vulnerabilities are available.

Note: These vulnerabilities are independent of each other. A device
may be affected by one vulnerability and not affected by another.

This advisory is posted at:

http://www.cisco.com/warp/public/707/cisco-sa-20100811-ace.shtml

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

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

The Cisco ACE Application Control Engine Module and Cisco ACE 4710
Application Control Engine are affected by multiple vulnerabilities.
Affected versions vary depending on the specific vulnerability. For
specific version information, refer to the Software Versions and
Fixes section of this advisory.

RTSP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cisco ACE Application Control Engine Module and Cisco ACE 4710
Application Control Engine appliances configured with RTSP inspection
are affected. RTSP inspection is disabled by default.

HTTP, RTSP, and SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cisco ACE 4710 Application Control Engine appliances configured with
HTTP, RTSP, or SIP inspection are affected. HTTP, RTSP, and SIP
inspection are disabled by default. The Cisco ACE Application Control
Engine Module is not affected by this vulnerability.

Note: This vulnerability is independent from the other RSTP and SIP
inspection vulnerabilities described in this advisory.

SSL DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~

Cisco ACE Application Control Engine Module processing SSL
transactions are affected by this vulnerability. The Cisco ACE 4710
Application Control Engine appliance is not affected by this
vulnerability.

SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cisco ACE Application Control Engine Module and Cisco ACE 4710
Application Control Engine appliances configured for SIP inspection
are affected. SIP inspection is disabled by default.

Determining Software Versions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To display the version of system software that is currently running
on Cisco ACE Application Control Engine, use the "show version"
command. This example displays the output of the "show version" command
on the Cisco ACE Application Control Engine software version A3(1.0):

    ACE-4710/Admin# show version
    Cisco Application Control Software (ACSW)
    TAC support: http://www.cisco.com/tac
    Copyright (c) 1985-2008 by Cisco Systems, Inc. All rights reserved.
    The copyrights to certain works contained herein are owned by
    other third parties and are used and distributed under license.
    Some parts of this software are covered under the GNU Public
    License. A copy of the license is available at
    http://www.gnu.org/licenses/gpl.html.

    Software
      loader:    Version 0.95
      system:    Version A3(1.0) [build 3.0(0)A3(0.0.148)]
      system image file: (nd)/192.168.65.31/scimitar.bin

      Device Manager version 1.1 (0) 20080805:0415

    ...
    <output truncated>

This example displays the output of the show version command on a
Cisco ACE Application Control Engine Module software version A2(3.0):

    ACEmod/Admin# show version
    Cisco Application Control Software (ACSW)
    TAC support: http://www.cisco.com/tac
    Copyright (c) 2002-2009, Cisco Systems, Inc. All rights reserved.
    The copyrights to certain works contained herein are owned by
    other third parties and are used and distributed under license.
    Some parts of this software are covered under the GNU Public
    License. A copy of the license is available at
    http://www.gnu.org/licenses/gpl.html.

    Software
      loader:    Version 12.2[121]
      system:    Version A2<3.0> [build 3.0(0)A2(2.99.80)]
      system image file: [LCP] disk0:c6ace-t1k9-mzg.A2_2_99_80.bin
      licensed features: no feature license is installed

    ...
    <output truncated>

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

The Cisco ACE XML Gateway, the Cisco ACE Web Application Firewall,
and the Cisco ACE GSS 4400 Series Global Site Selector Appliances are
not affected by any of the vulnerabilities that are described in this
advisory.

No other Cisco products are currently known to be affected by these
vulnerabilities.

Details
=======

The Cisco ACE 4710 Application Control Engine appliance and the Cisco
ACE Application Control Engine Module for Cisco Catalyst 6500 Series
Switches and Cisco 7600 Series Routers are a load-balancing and
application-delivery solution for data centers. Multiple
vulnerabilities exist in both products. These vulnerabilities are
independent of each other. A device may be affected by one
vulnerability and not affected by another. The following information
provides the details about each of the vulnerabilities that are
addressed in this advisory.

RTSP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The RTSP is used by RealAudio, RealNetworks, Apple QuickTime 4,
RealPlayer, and Cisco IP/TV connections. RTSP applications use the
well-known port 554 with TCP and UDP as the control channel. The
module and the appliance only support RTSP over TCP.

The Cisco ACE Application Control Engine Module and Cisco ACE 4710
Application Control Engine contain a DoS vulnerability that can be
exploited by an unauthenticated attacker while sending crafted RTSP
packets. Only devices with RTSP inspection enabled are affected. RTSP
inspection is disabled by default.

Note: A TCP three-way handshake is needed in order to exploit this
vulnerability. Only transit traffic can trigger this vulnerability;
traffic that is destined to the affected device will not trigger the
vulnerability.

This vulnerability is documented in these Cisco Bug IDs and has been
assigned these Common Vulnerability and Exposures (CVE) IDs:

  * Cisco ACE Application Control Engine Appliance: CSCta85227 - CVE-2010-2822
  * Cisco ACE Application Control Engine Module: CSCtg14858 - CVE-2010-2822

HTTP, RTSP, and SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ACE performs a stateful deep packet inspection of the HTTP
protocol. Deep packet inspection is a special case of application
inspection where the ACE examines the application payload of a packet
or a traffic stream and makes decisions based on the content of the
data. During HTTP deep inspection, the main focus of the application
inspection process is on HTTP attributes such as the HTTP header, the
URL, and to a limited extent, the payload. User-defined regular
expressions can also be used to detect "signatures" in the payload.

The Cisco ACE 4710 Application Control Engine contains a DoS
vulnerability that can be exploited by an unauthenticated attacker
while sending crafted HTTP packets. Devices with HTTP, RTSP, or SIP
inspection enabled are affected. HTTP, RTSP, and SIP inspection are
disabled by default.

Note: The Cisco ACE Application Control Engine Module is not affected
by this vulnerability. A TCP three-way handshake is needed in order
to exploit this vulnerability. Only transit traffic can trigger this
vulnerability; traffic that is destined to the affected device will
not trigger this vulnerability.

This vulnerability is documented in Cisco Bug ID CSCtb54493 and
has been assigned the CVE ID CVE-2010-2823.

SSL DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~

The Cisco ACE Application Control Engine Module contains a DoS
vulnerability that can be exploited by an unauthenticated attacker
while sending a series of SSL packets. The Cisco ACE 4710 Application
Control Engine appliance is not affected by this vulnerability.

Note: A TCP three-way handshake is needed in order to exploit this
vulnerability. Only traffic that is destined to the affected device
can trigger this vulnerability; transit traffic will not trigger this
vulnerability.

Note: The Cisco ACE 4710 Application Control Engine appliance is not
affected by this vulnerability.

This vulnerability is documented in Cisco Bug ID CSCta20756 and has
been assigned the CVE ID CVE-2010-2824.

SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SIP is used for call handling sessions, especially two-party
conferences. The Cisco ACE Application Control Engine Module and
Cisco ACE 4710 Application Control Engine contain a DoS vulnerability
that can be exploited by an unauthenticated attacker while sending
crafted SIP packets. Only devices with SIP inspection enabled are
affected. SIP inspection is disabled by default.

Note: TCP or UDP SIP packets may cause a device reload. If TCP is
used, a TCP three-way handshake is needed in order to exploit this
vulnerability. Only transit traffic can trigger this vulnerability;
traffic that is destined to the affected device will not trigger this
vulnerability.

This vulnerability is documented in these Cisco Bug IDs and has been
assigned these CVE IDs:

  * Cisco ACE Application Control Engine Module: CSCta65603 - CVE-2010-2825
  * Cisco ACE Application Control Engine Appliance: CSCta71569 - CVE-2010-2825

Vulnerability Scoring Details
=============================

Cisco has provided scores for the vulnerabilities in this advisory
based on the Common Vulnerability Scoring System (CVSS). The CVSS
scoring in this Security Advisory is done in accordance with CVSS
version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability
severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then
compute environmental scores to assist in determining the impact of
the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding
CVSS at:

http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html

Cisco has also provided a CVSS calculator to help compute the
environmental impact for individual networks at:

http://intellishield.cisco.com/security/alertmanager/cvss

CSCta85227, CSCtg14858 - RTSP Inspection DoS Vulnerability

CVSS Base Score - 7.8

Access Vector           - Network
Access Complexity       - Low
Authentication          - None
Confidentiality Impact  - None
Integrity Impact        - None
Availability Impact     - Complete

CVSS Temporal Score - 6.4

Exploitability          - Functional
Remediation Level       - Official-Fix
Report Confidence       - Confirmed

CSCtb54493 - HTTP, RTSP, and SIP Inspection DoS Vulnerability

CVSS Base Score - 7.8

Access Vector           - Network
Access Complexity       - Low
Authentication          - None
Confidentiality Impact  - None
Integrity Impact        - None
Availability Impact     - Complete

CVSS Temporal Score - 6.4

Exploitability          - Functional
Remediation Level       - Official-Fix
Report Confidence       - Confirmed

CSCta20756 - SSL DoS Vulnerability

CVSS Base Score - 7.8

Access Vector           - Network
Access Complexity       - Low
Authentication          - None
Confidentiality Impact  - None
Integrity Impact        - None
Availability Impact     - Complete

CVSS Temporal Score - 6.4

Exploitability          - Functional
Remediation Level       - Official-Fix
Report Confidence       - Confirmed

CSCta65603, CSCta71569 - SIP Inspection DoS Vulnerability

CVSS Base Score - 7.8

Access Vector           - Network
Access Complexity       - Low
Authentication          - None
Confidentiality Impact  - None
Integrity Impact        - None
Availability Impact     - Complete

CVSS Temporal Score - 6.4

Exploitability          - Functional
Remediation Level       - Official-Fix
Report Confidence       - Confirmed

Impact
======

Successful exploitation of any of the vulnerabilities described in
this security advisory may cause a reload of the affected device.
Repeated exploitation could result in a sustained DoS condition.

Software Versions 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.

Each row of the software table (below) describes the earliest
possible releases that contain the fix (along with the anticipated
date of availability for each, if applicable) are listed in the
"First Fixed Release" column of the table. The "Recommended Release"
column indicates the releases which have fixes for all the published
vulnerabilities at the time of this Advisory. A device running a
release in the given train that is earlier than the release in a
specific column (less than the First Fixed Release) is known to be
vulnerable. Cisco recommends upgrading to a release equal to or later
than the release in the "Recommended Releases" column of the table.

+--------------------------------------------------------------+
|               | First Fixed Release     | Recommended        |
|               |                         | Release            |
|Vulnerability  |-------------------------+--------------------|
|               | ACE        | ACE Module | ACE       | ACE    |
|               | Appliance  |            | Appliance | Module |
|---------------+------------+------------+-----------+--------|
| RTSP          |            |            |           | A2     |
| Inspection    | A3(2.6)    | A2(3.2)    | A3(2.6)   | (3.2)  |
| Vulnerability |            |            |           |        |
|---------------+------------+------------+-----------+--------|
| HTTP, RTSP,   |            |            |           |        |
| SIP           | A3(2.6)    | Not        | A3(2.6)   | A2     |
| Inspection    |            | vulnerable |           | (3.2)  |
| Vulnerability |            |            |           |        |
|---------------+------------+------------+-----------+--------|
|               |            | A2(1.6)    |           |        |
| SSL           | Not        |            |           | A2     |
| Vulnerability | vulnerable | A2(2.3)    | A3(2.6)   | (3.2)  |
|               |            |            |           |        |
|               |            | A2(3.1)    |           |        |
|---------------+------------+------------+-----------+--------|
|               |            | A2(1.6)    |           |        |
| SIP           |            |            |           | A2     |
| Inspection    | A3(2.4)    | A2(2.3)    | A3(2.6)   | (3.2)  |
| Vulnerability |            |            |           |        |
|               |            | A2(3.1)    |           |        |
+--------------------------------------------------------------+

Cisco ACE 4710 Application Control Engine appliance software can be
downloaded from:

http://tools.cisco.com/support/downloads/go/Redirect.x?mdfid=281222179

Cisco ACE Module software can be downloaded from:

http://tools.cisco.com/support/downloads/go/Redirect.x?mdfid=280557289

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

In addition to the recommendations described below, mitigation
techniques that can be deployed on Cisco devices within the network
are available in the Cisco Applied Mitigation Bulletin companion
document for this advisory:

http://www.cisco.com/warp/public/707/cisco-amb-20100811-ace.shtml

RTSP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This vulnerability can be mitigated by disabling RTSP inspection if
it is not required. RTSP inspection is disabled by default.
Administrators can disable RTSP inspection by issuing the "no inspect
rtsp" command under the respective policy map.

Note: This workaround is only feasible if RTSP inspection is not
needed or required in a load-balancing deployment.

HTTP, RTSP, and SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This vulnerability can be mitigated by disabling HTTP, RTSP, and SIP
inspection if they are not required. HTTP, RTSP, and SIP inspection
are disabled by default.

Administrators can disable HTTP inspection by issuing the "no inspect
http" command under the respective policy map.

Administrators can disable RTSP inspection by issuing the "no inspect
rtsp" command under the respective policy map.

Administrators can disable SIP inspection by issuing the "no inspect
sip" command under the respective policy map.

Note: This workaround is only feasible if HTTP, RTSP, and SIP
inspections are not needed or required in a load-balancing
deployment.

SSL DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~

There are no workarounds available to mitigate this vulnerability.

SIP Inspection DoS Vulnerability
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This vulnerability can be mitigated by disabling SIP inspection if it
is not required. SIP inspection is disabled by default.
Administrators can disable SIP inspection by issuing the "no inspect
sip" command under the respective policy map.

Note: This workaround is only feasible if SIP inspection is not
needed or required in a load-balancing deployment.

Obtaining Fixed Software
========================

Cisco has released free software updates that address these
vulnerabilities. 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/en/US/docs/general/warranty/English/EU1KEN_.html

or as otherwise set forth at Cisco.com Downloads at:

http://www.cisco.com/public/sw-center/sw-usingswc.shtml

Do not contact psirt at cisco.com or security-alert at 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 without Service Contracts
+----------------------------------

Customers who purchase direct from Cisco but do not hold a Cisco
service contract, and customers who purchase through third-party
vendors but are unsuccessful in obtaining fixed software through
their point of sale should acquire 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 at cisco.com

Customers should have their product serial number available and be
prepared to give the URL of this notice as evidence of entitlement to
a free upgrade. Free upgrades for non-contract customers must be
requested through the TAC.

Refer to:

http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html

for additional TAC contact information, including 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.

These vulnerabilities were found during the troubleshooting of
customer service requests and internal testing.

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-20100811-ace.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 at cisco.com
  * first-bulletins at lists.first.org
  * bugtraq at securityfocus.com
  * vulnwatch at vulnwatch.org
  * cisco at spot.colorado.edu
  * cisco-nsp at puck.nether.net
  * full-disclosure at lists.grok.org.uk
  * comp.dcom.sys.cisco at 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      | 2010-August-11 | 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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