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Cisco Security Response

Cisco IOS Software Denial of Service Vulnerabilities

Document ID: 645

http://tools.cisco.com/security/center/content/CiscoSecurityResponse/cisco-sr-20110505-ios

Revision 1.1

Last Updated on 2011 June 20 16:00  UTC (GMT)

For Public Release 2011 April 5 16:00  UTC (GMT)


Contents

Response
Additional Information
Status of this Notice: Final
Revision History
Cisco Security Procedures

Cisco Response

This is the Cisco PSIRT (Product Security Incident Response Team) response to two postings on BugTraq by NCNIPC (China) regarding reported vulnerabilities in Cisco IOS Software.

The original reports are available at the following links:

We greatly appreciate the opportunity to work with researchers on security vulnerabilities and welcome the opportunity to review and assist in product reports.

Additional Information

Cisco PSIRT obtained further information from NCNIPC (China) about how the testing of the reported vulnerabilities was performed.

Cisco PSIRT can confirm that no new vulnerabilities have been discovered. The Cisco 2911 Integrated Services Router (ISR) that was used to perform testing had no control plane protection configured, which Cisco recommends as a best practice. The Cisco 2911 ISR was tested by sending large amounts of untrusted traffic to an infrastructure address. The device has to process switch these packets and reply with an ICMP unreachable message (rate limited based on the ip icmp rate-limit unreachable configuration command), which increases CPU utilization.

Cisco has performed testing on the Cisco ISR range of products, and the devices can handle such attacks if proper control plane protection is configured. Cisco PSIRT recommends configuring control plane protection as a best practice. This protection mechanism is outlined in the document "Cisco Guide to Harden Cisco IOS Devices", which is available from the following location: http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a 0080120f48.shtml

Best practices indicate that network administrators should identify traffic that should never be allowed to target infrastructure devices and block that traffic at the border of networks and on individual devices using hardening configuration features like infrastructure access control lists (iACLs), receive access control lists (rACLs), Control Plane Policing (CoPP), and Modular Quality of Service (QoS) Command-Line Interface (MQC).

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.


Revision History

Revision 1.1

2011-June-20

Cisco has published a final conclusion after investigating the reported vulnerabilities.

Revision 1.0

2011-May-05

Initial 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/web/about/security/psirt/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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