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Cisco Security Advisory

ACNS Denial of Service and Default Admin Password Vulnerabilities

Severity
Advisory ID:
cisco-sa-20050224-acnsdos
First Published:
2005 February 24 16:00 GMT
Version 1.0:
Final

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:

    This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20050224-acnsdos.

Affected Products

  • Vulnerable Products

    DDTS Bug ID

    Vulnerable ACNS Versions

    CSCef27476

    5.0 prior to release 5.0.17.6

    5.1 prior to release 5.1.11.6

    CSCef30460

    All 4.X releases

    All 5.0 releases

    5.1 prior to release 5.1.11.6

    CSCeg49648

    All 5.1 releases

    CSCeg23731

    All 5.0 releases

    5.1 prior to release 5.1.13.7

    5.2 prior to release 5.2.3.9

    CSCef30743

    All 4.X releases

    All 5.0 releases

    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.

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.
    • 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
      More information about the username command can be found at:
    • 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.

Fixed Software

  • 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.

    DDTS Bug ID

    Vulnerable ACNS Versions

    Fixed Versions

    CSCef27476

    5.0 prior to release 5.0.17.6

    5.0.17.6 and later

    5.1 prior to release 5.1.11.6

    5.1.11.6 and later

    CSCef30460

    All 4.X releases

    Upgrade to 5.1.11.6 and later

    All 5.0 releases

    Upgrade to 5.1.11.6 and later

    5.1 prior to release 5.1.11.6

    5.1.11.6 and later

    CSCeg49648

    All 5.1 releases

    Upgrade to 5.2.1.7 or later

    CSCeg23731

    All 5.0 releases

    Upgrade to 5.1.13.7 and later or upgrade to 5.2.3.9 and later

    5.1 prior to release 5.1.13.7

    5.1.13.7 and later

    5.2 prior to release 5.2.3.9

    5.2.3.9 and later

    CSCef30743

    All 4.X, 5.0, 5.1, and 5.2 releases

    Upgrade not required. Implement the workaround detailed in 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

      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

      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

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

Exploitation and Public Announcements

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

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Revision History

  • Revision 1.0

    2005-February-24

    Initial public release.
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Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications