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Cisco Security Advisory: ACNS Denial of Service and Default Admin Password Vulnerabilities
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Thursday, 24 Feb 2005 10:00:00 -0600

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Cisco Security Advisory: Cisco Security Advisory: ACNS Denial of
Service and Default Admin Password Vulnerabilities
======================================================================

Revision 1.0

For Public Release 2005 February 24 1600 UTC (GMT)

Contents
========

    Summary
    Affected Products
    Details
    Impact
    Software Versions and Fixes
    Obtaining Fixed Software
    Workarounds
    Exploitation and Public Announcements
    Status of This Notice: FINAL
    Distribution
    Revision History
    Cisco Security Procedures
   


Summary
=======

Devices running Cisco Application and Content Networking System
(ACNS) software may be vulnerable to Denial of Service (DoS) attacks
and may contain a default password for the administrative account.
Devices running ACNS software may be vulnerable to the DoS attacks
while configured as a transparent proxy server, forward proxy server,
or reverse proxy server. Cisco has made free software available to
address the DoS vulnerabilities for all affected customers. The
administrative account default password does not require a software
upgrade and can be changed by a configuration command for all
affected customers. There are workarounds available to mitigate the
effects of two of the vulnerabilities.

The vulnerabilities are documented as the following Cisco Bug IDs:

  * CSCef27476
  * CSCef30460
  * CSCeg49648
  * CSCeg23731
  * CSCef30743  

This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20050224-acnsdos.shtml.

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

Vulnerable Products
- -----------------

+---------------------------------+
|  DDTS Bug ID   |Vulnerable ACNS |
|                |    Versions    |
|----------------+----------------|
|                |5.0 prior to    |
|                |release 5.0.17.6|
|CSCef27476      |----------------|
|                |5.1 prior to    |
|                |release 5.1.11.6|
|----------------+----------------|
|                |All 4.X releases|
|                |----------------|
|CSCef30460      |All 5.0 releases|
|                |----------------|
|                |5.1 prior to    |
|                |release 5.1.11.6|
|----------------+----------------|
|CSCeg49648      |All 5.1 releases|
|----------------+----------------|
|                |All 5.0 releases|
|                |----------------|
|                |5.1 prior to    |
|CSCeg23731      |release 5.1.13.7|
|                |----------------|
|                |5.2 prior to    |
|                |release 5.2.3.9 |
|----------------+----------------|
|                |All 4.X releases|
|                |----------------|
|                |All 5.0 releases|
|CSCef30743      |----------------|
|                |All 5.1 releases|
|                |----------------|
|                |All 5.2 releases|
+---------------------------------+

The hardware models that support ACNS are:

  * Cisco 500 Series Content Engines
  * Cisco 7300 Series Content Engines
  * Cisco Content Routers 4400 series
  * Cisco Content Distribution Manager 4600 series
  * Cisco Content Engine Module for Cisco 2600, 2800, 3600, 3700, and
    3800 series Integrated Service Routers

To determine the ACNS software running on a supported device, log in
to the device and issue the  "show version"  command to display the
system banner. Cisco ACNS Software will identify itself as  
Application and Content Networking System Software (ACNS) . Below the
copyright information the ACNS release and build information is
displayed.

The following example identifies a Cisco device running ACNS software
release 5.1.5.2:

    Application and Content Networking System Software (ACNS)
     
    Copyright 1999-2003 by Cisco Systems, Inc.
     
    Application and Content Networking System Software Release 5.1.5 
    (build b2 Mar 30 2004)

To match the release and build information from the device with the
software release information in this advisory and available on CCO,
append the release with the build code and replace the lowercase 'b'
with a dot (example: 5.1.5b2 becomes 5.1.5.2)

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

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

Details
=======

ACNS software provides web application acceleration and caching
services. Cisco ACNS software combines the technologies of
demand-pull caching, pre-positioning, and live and on-demand
streaming to accelerate delivery of web applications, object files,
live events, and video. Bandwidth-intensive content objects, such as
Java applets, Flash animations, Shockwave programs, and other file
formats can be managed and scheduled for distribution to Content
Engines during off-peak hours.

Cisco ACNS software may be vulnerable to four DoS attacks and may
contain a default password for the administrative account. Devices
running ACNS software may be vulnerable to the DoS attacks while
configured as a transparent proxy server, forward proxy server, or
reverse proxy server. The issues are detailed below:

  * CSCef27476 - A specifically crafted Transmission Control Protocol
    (TCP) connection may cause the ACNS cache process to restart
    resulting in a loss of cached information and degraded service of
    web browser content requests. Repeated exploitation could result
    in a sustained DoS attack against the caching functionality of
    the device.

  * CSCef30460 - Certain malformed IP packets may cause the CPU
    utilization on the affected device to go to 100% resulting in a
    degradation of all services. A reboot of the device is required
    to recover from the high CPU. Repeated exploitation could result
    in a sustained DoS attack.

  * CSCeg49648 - Certain malformed packets may cause the RealServer
    RealSubscriber to consume 100% of the affected device s CPU
    resulting in a degradation of all services. A reboot of the
    device is required to recover from the high CPU. Repeated
    exploitation could result in a sustained DoS attack.

  * CSCeg23731 - Certain crafted IP packets may cause the ACNS to
    continuously forward copies of the crafted packet until all
    network bandwidth is consumed and network utilization reaches
    100%. This could result in a denial of service to the affected
    device and other devices on the same local network segment with
    the affected device. A reboot of the device is required to
    recover from this condition. Repeated exploitation could result
    in a sustained DoS attack to all devices on the local network
    segment.

  * CSCef30743 - The administrative password is set to a default
    password that is the same in all installations if the ACNS setup
    dialog has not been previously run or the administrative password
    has not been manually changed. All enabled services will use the
    default credential.

Impact
======

  * CSCef27476 - Exploitation of this vulnerability may cause a loss
    of cached information and degraded service of web browser content
    requests. Repeated exploitation could result in a sustained DoS
    attack against the caching functionality of the device.

  * CSCef30460 - Exploitation of this vulnerability may cause a
    degradation of all services provided by the affected device.
    Repeated exploitation could result in a sustained DoS attack.

  * CSCeg49648 - Exploitation of this vulnerability may cause a
    degradation of all services provided by the affected device.
    Repeated exploitation could result in a sustained DoS attack.

  * CSCeg23731 - Exploitation of this vulnerability may cause a
    denial of service to the affected device and other devices on the
    same local network segment Repeated exploitation could result in
    a sustained DoS attack.

  * CSCef30743 - An attacker who is able to log into an ACNS device
    using the default administrative password has full control of the
    device, which includes the ability to change device
    configurations.

Software Versions and Fixes
===========================

When considering software upgrades, please also consult 
http://www.cisco.com/en/US/products/products_security_advisories_listing.html 
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") for assistance.

+--------------------------------------+
|           | Vulnerable |    Fixed    |
|DDTS Bug ID|    ACNS    |  Versions   |
|           |  Versions  |             |
|-----------+------------+-------------|
|           |5.0 prior to|5.0.17.6 and |
|           |release     |later        |
|           |5.0.17.6    |             |
|CSCef27476 |------------+-------------|
|           |5.1 prior to|5.1.11.6 and |
|           |release     |later        |
|           |5.1.11.6    |             |
|-----------+------------+-------------|
|           |All 4.X     |Upgrade to   |
|           |releases    |5.1.11.6 and |
|           |            |later        |
|           |------------+-------------|
|           |All 5.0     |Upgrade to   |
|CSCef30460 |releases    |5.1.11.6 and |
|           |            |later        |
|           |------------+-------------|
|           |5.1 prior to|5.1.11.6 and |
|           |release     |later        |
|           |5.1.11.6    |             |
|-----------+------------+-------------|
|           |All 5.1     |Upgrade to   |
|CSCeg49648 |releases    |5.2.1.7 or   |
|           |            |later        |
|-----------+------------+-------------|
|           |            |Upgrade to   |
|           |            |5.1.13.7 and |
|           |All 5.0     |later or     |
|           |releases    |upgrade to   |
|           |            |5.2.3.9 and  |
|           |            |later        |
|CSCeg23731 |------------+-------------|
|           |5.1 prior to|5.1.13.7 and |
|           |release     |later        |
|           |5.1.13.7    |             |
|           |------------+-------------|
|           |5.2 prior to|5.2.3.9 and  |
|           |release     |later        |
|           |5.2.3.9     |             |
|-----------+------------+-------------|
|           |            |Upgrade not  |
|           |            |required.    |
|           |All 4.X,    |Implement the|
|           |5.0, 5.1,   |workaround   |
|CSCef30743 |and 5.2     |detailed in  |
|           |releases    |the          |
|           |            |Workarounds  |
|           |            |section if   |
|           |            |necessary    |
+--------------------------------------+

Upgrade procedures can be found in the following documents:

* Cisco ACNS Software Deployment and Configuration Guide, Release
  5.0 Chapter 10: Upgrading and Downgrading the Software

  http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce/acns50/deploy50/50upgrd.htm

  Note: This procedure includes steps for migrating from 4.X software
  to ACNS 5.X software

* Cisco ACNS Software Deployment and Configuration Guide, Release
  5.1 Chapter 15: Upgrading and Downgrading the Software
    
  http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce/acns51/deploy51/51upgrd.htm

  Note: This procedure includes steps for migrating from 4.X software
  to ACNS 5.X software

* Cisco ACNS Software Configuration Guide for Centrally Managed
  Deployments, Release 5.2 Chapter 17: Upgrading and Downgrading 
  the Software

  http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce/acns52/dcg52/5645upgd.htm

  Note: This procedure includes steps for migrating from 4.X software
  to ACNS 5.X software


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

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 assistance with the
upgrade, which should be free of charge.

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

If you need assistance with the implementation of the workarounds, or
have questions on the workarounds, please contact the Cisco TAC.

Please 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.

Please do not contact either "psirt () cisco com" or
"security-alert () cisco com" for software upgrades.

See 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.

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.

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

The effectiveness of any workaround 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 is the most
appropriate for use in the intended network before it is deployed.

  * For Denial of Service vulnerability CSCeg49648. RealServer
    RealSubscriber if it is running. By default the RealServer
    RealSubscriber is disabled. Disabling RealServer RealSubscriber
    will prevent the ACNS device from acting as a RealServer
    streaming media caching subscriber. To verify if the RealServer
    RealSubscriber is running, use the command "show rtsp server
    real-subscriber". The following output shows an enabled
    RealServer RealSubscriber:

 
       cacheengine#show rtsp server
 
       Real Subscriber version: ce7325-9.0.2.855
       Real Subscriber enabled
       Real Subscriber running
       Real Subscriber end user license agreement accepted
       Real Subscriber evaluation enabled. Estimated 17 days 21 hours
       left for evaluation.
       Real Subscriber license key not installed
       Real Subscriber bandwidth enforced is 522240 kbps
 
 

    To disable the RealServer RealSubscriber, use the command "no rtsp
    server real-subscriber enable" while in global configuration mode
    as shown below:


       cacheengine#configure terminal
       cacheengine(config)#no rtsp server real-subscriber enable
       cacheengine(config)#exit

    The following output shows a disabled RealServer RealSubscriber:

       cacheengine# show rtsp server real-subscriber 
 
       Real Subscriber version: ce7325-9.0.2.855
       Real Subscriber not enabled
       Real Subscriber not running
       Real Subscriber end user license agreement accepted
       Real Subscriber evaluation enabled. Estimated 17 days 21 hours
       left for evaluation.
       Real Subscriber license key not installed
       Real Subscriber bandwidth enforced is 522240 kbps

    More information about the RealServer RealSubscriber 
    implementation can be found in the Enabling RealSubscriber 
    section of the Cisco ACNS Software Deployment and Configuration
    Guide, Release 5.1.

    http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce
    /acns51/deploy51/51stream.htm#wp1039106


  * For the potential default password issue CSCef30743, if the  
    "setup dialog" has been previously run or the administrative
    password previously changed the workaround is not required. If
    the "setup dialog" has not been run or the administrative
    password has not been changed, the workaround is to manually
    change the "admin" account password. To change the default
    password, users should run the "username" command once they have
    logged in as the "admin" user. The following interaction shows an
    example of a change password dialog on a Content Engine that is
    performed via the console port:

      Username: admin
      Password:
      System Initialization Finished.
      Cacheengine#configure terminal
      cacheengine(config)#username admin password <password> 

    More information about the username command can be found at:

      * Cisco ACNS 5.2 Software Commands - username
      http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce
      /acns52/cref52/5754ref.htm#wp1058250

 
      * Cisco ACNS 5.1 Software Commands - username
      http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce
      /acns51/cref51/4068ref.htm#1058250
 

      * Cisco ACNS 5.0 Software Commands - username
      http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce
      /acns50/cref50/14623ref.htm#2395638
 

      * Cisco ACNS 4.2 Software Commands - username
      http://www.cisco.com/univercd/cc/td/doc/product/webscale/uce
      /acns42/cmdref42/14388ref.htm#1035531


  * For the Denial of Service vulnerabilities CSCef27476, CSCef30460,
    and CSCeg23731, access-control lists (ACLs) can be used to reduce
    exposure to these vulnerabilities. Configure ACLs on the ACNS
    device and on screening routers, switches and firewalls that
    filter internal and external traffic to the ACNS device so that
    IP traffic is only allowed from legitimate, trusted IP addresses.

      * Refer to 
        http://www.cisco.com/univercd/cc/td/doc/product/webscale/
        uce/acns52/ldg52/acls.htm 
        for information on creating and managing IP access control
        lists for standalone content engines.
        
      * Refer to 
        http://www.cisco.com/univercd/cc/td/doc/product/webscale/
        uce/acns52/dcg52/5645acl.htm 
        for information on creating and managing IP access 
        control lists for centrally managed content engines.
        
      * Refer to 
        http://www.cisco.com/warp/public/707/tacl.html 
        for examples on how to apply ACLs on Cisco routers.
        
      * For more information on anti-spoofing, refer to 
        http://www.cisco.com/en/US/tech/tk648/tk361/
        technologies_tech_note09186a0080120f48.shtml#sec_ip 
        and 
        http://www.ietf.org/rfc/rfc2827.txt 

      * The Unicast Reverse Path Forwarding (Unicast RPF) feature
        helps to mitigate problems that are caused by spoofed IP
        source addresses. It is available on Cisco routers and
        firewalls. For further details, please refer to 
        http://www.cisco.com/univercd/cc/td/doc/product/software/
        ios122/122cgcr/fsecur_c/fothersf/scfrpf.htm.


Exploitation and Public Announcements
=====================================

The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerability described in this advisory.

Status of This Notice: FINAL
============================

THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY
KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF
MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE ADVISORY OR
MATERIALS LINKED FROM THE ADVISORY IS AT YOUR OWN RISK. CISCO
RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY TIME.

A stand-alone copy or paraphrase of the text of this security
advisory 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-20050224-acnsdos.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 (includes CERT/CC)
  * bugtraq () securityfocus com
  * vulnwatch () vulnwatch org
  * cisco () spot colorado edu
  * cisco-nsp () puck nether net
  * full-disclosure () lists netsys com
  * 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      |2005-February-24  |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.

All contents are Copyright © 1992-2005 Cisco Systems, Inc. All rights
reserved.

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