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Message-ID: <200502241000.acnsdos@psirt.cisco.com>
From: psirt at cisco.com (Cisco Systems Product Security Incident Response Team)
Subject: Cisco Security Advisory: ACNS Denial of Service
and Default Admin Password Vulnerabilities
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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@...co.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@...co.com" or
"security-alert@...co.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@...co.com
* first-teams@...st.org (includes CERT/CC)
* bugtraq@...urityfocus.com
* vulnwatch@...nwatch.org
* cisco@...t.colorado.edu
* cisco-nsp@...k.nether.net
* full-disclosure@...ts.netsys.com
* comp.dcom.sys.cisco@...sgate.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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