Advisory ID: cisco-sa-20130327-ipsla
Last Updated 2013 April 12 14:44 UTC (GMT)
For Public Release 2013 March 27 16:00 UTC (GMT)
Vulnerability Scoring Details
Software Versions and Fixes
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: Final
Cisco Security Procedures
The Cisco IOS Software implementation of the IP Service Level Agreement (IP SLA) feature contains a vulnerability in the validation of IP SLA packets that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
Cisco has released free software updates that address this vulnerability. Mitigations for this vulnerability are available.
This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130327-ipsla
Note: The March 27, 2013, Cisco IOS Software Security Advisory bundled publication includes seven Cisco Security Advisories. All advisories address vulnerabilities in Cisco IOS Software. Each Cisco IOS Software Security Advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all Cisco IOS Software vulnerabilities in the March 2013 bundled publication.
Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Security Advisory Bundled Publication" at the following link:
This vulnerability affects a device that is running an affected version of Cisco IOS Software and has a vulnerable IP SLA general responder configuration.
Cisco devices that are running Cisco IOS Software are vulnerable when they are configured for the IP SLA general responder feature.
There are two methods to determine whether a device is configured for the IP SLA general responder:
- Determine whether the IP SLA general responder command is included in the device configuration.
- Determine whether the IP SLA general responder is active on a running device.
Determine Whether IP SLA General Responder Command Is Included in the Device Configuration
To determine whether the IP SLA general responder has been enabled in the Cisco IOS Software configuration. The ip sla responder global configuration command must be present The show running-config | include ip sla responder command can be used to determine whether IP SLA is present in the configuration, as illustrated in the following example:
Router> show running-config | include ip sla responder$ ip sla responder Router>
Determine Whether IP SLA General Responder Is Active on a Running Device
The administrator can establish whether the IP SLA general responder is enabled on a Cisco IOS device by using the show ip sla responder | include ^General command. If the vulnerable IP SLA general responder is active, the output will include a line with Enabled.
The following example shows a device on which the vulnerable IP SLA responder is active:
Router# show ip sla responder | include ^General General IP SLA Responder is: Enabled Router#
Determine the Cisco IOS Software Release
To determine the Cisco IOS Software release that is running on a Cisco product, administrators can log in to the device and issue the show version command to display the system banner. The system banner confirms that the device is running Cisco IOS Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the show version command or may provide different output.
The following example identifies a Cisco product that is running Cisco IOS Software Release 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:
Router> show version
Cisco IOS Software, C3900 Software (C3900-UNIVERSALK9-M), Version 15.0(1)M1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Wed 02-Dec-09 17:17 by prod_rel_team
!--- output truncated
Additional information about Cisco IOS Software release naming conventions is available in "White Paper: Cisco IOS and NX-OS Software Reference Guide" at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.
The following products have been confirmed not vulnerable:
- Cisco IOS XR Software
- Cisco NX-OS Software
- Cisco ASA Software
The IP SLA Responder is a component embedded in a Cisco routing device that allows the system to anticipate and respond to IP SLA request packets. There are two types of IP SLA responders:
- IP SLA general responder uses the IP SLA Control Protocol to set up IP SLA operations and receives packets on UDP port 1167 or on UDP port 1967.
- IP SLA permanent responder receives either UDP or TCP packets on a user-configurable port.
A vulnerability in the implementation of the IP Service Level Agreement general responder feature of Cisco IOS Software could allow an unauthenticated, remote attacker to cause a reload of the vulnerable device. The vulnerability is due to improper validation of IP SLA packets only when they are received on UDP port 1167. An attacker could exploit this vulnerability by sending malformed IP SLA packets addressed to the affected device. An exploit could allow the attacker to cause an extended DoS condition.
This vulnerability can be exploited via IP version 4 (IPv4) or IP version 6 (IPv6).
Neither the IP SLA general responder on UDP port 1967 nor the permanent UDP responder are affected by this vulnerability.
Cisco has scored the vulnerability in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this security advisory is in accordance with CVSS version 2.0.
CVSS is a standards-based scoring method that conveys vulnerability severity and helps organizations determine the urgency and priority of a response.
Cisco has provided a base and temporal score. Customers can also compute environmental scores that help determine the impact of the vulnerability in their own networks.
Cisco has provided additional information regarding CVSS at the following link:
Cisco has also provided a CVSS calculator to compute the environmental impact for individual networks at the following link:
CSCuc72594 Cisco IOS IP SLA General Responder Vulnerability
Calculate the environmental score of CSCuc72594
CVSS Base Score - 7.8
CVSS Temporal Score - 6.4
Successful exploitation of the vulnerability may cause a vulnerable device to reload.
Continued exploitation will result in a sustained DoS attack.
When considering software upgrades, customers are advised to consult the Cisco Security Advisories, Responses, and Notices archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Cisco IOS Software
Each row of the following Cisco IOS Software table corresponds to a Cisco IOS Software train. If a particular train is vulnerable, the earliest releases that contain the fix are listed in the First Fixed Release column. The First Fixed Release for All Advisories in the March 2013 Bundled Publication column lists the earliest possible releases that correct all the published vulnerabilities in the Cisco IOS Software Security Advisory bundled publication. Cisco recommends upgrading to the latest available release where possible.
The Cisco IOS Software Checker allows customers to search for Cisco Security Advisories that address specific Cisco IOS Software releases. This tool is available on the Cisco Security (SIO) portal at http://tools.cisco.com/security/center/selectIOSVersion.x
|Major Release||Availability of Repaired Releases|
|Affected 12.0-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 12.0 based releases|
|Affected 12.2-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 12.2 based releases|
|Affected 12.3-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 12.3 based releases|
|Affected 12.4-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 12.4 based releases|
|Affected 15.0-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 15.0 based releases|
|Affected 15.1-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 15.1 based releases|
|Affected 15.2-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
||Vulnerable; migrate to any release in 15.4T
||Vulnerable; migrate to any release in 15.4T
|15.2S||Vulnerable. Only releases 15.2(4)S through 15.2(4)S1 are vulnerable.
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.2(4)S2 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
||Vulnerable; contact your support organization per the instructions in
Obtaining Fixed Software section of this advisory.
||Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.|
||15.2(1)T4; Available on 03-MAY-13
|Affected 15.3-Based Releases||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Bundled Publication|
|There are no affected 15.3 based releases|
Cisco IOS XE Software is affected by the vulnerability that is disclosed in this document.
|Cisco IOS XE Software Release||First Fixed Release||First Fixed Release for All Advisories in the March 2013 Cisco IOS Software Security Advisory Bundled Publication|
|2.1.x||Not vulnerable||Not vulnerable|
|2.2.x||Not vulnerable||Not vulnerable|
|2.3.x||Not vulnerable||Not vulnerable|
|2.4.x||Not vulnerable||Not vulnerable|
|2.5.x||Not vulnerable||Not vulnerable|
|2.6.x||Not vulnerable||Not vulnerable|
|3.1.xS||Not vulnerable||Vulnerable; migrate to 3.4.5S or later.|
|3.1.xSG||Not vulnerable||Not vulnerable|
|3.2.xS||Not vulnerable||Vulnerable; migrate to 3.4.5S or later.|
|3.2xSE||Not vulnerable||Not vulnerable|
|3.2.xSG||Not vulnerable||Not vulnerable|
|3.2.XO||Not vulnerable||Not vulnerable|
|3.2.xSQ||Not vulnerable||Not vulnerable|
|3.3.xS||Not vulnerable||Vulnerable; migrate to 3.4.5S or later.|
|3.3xSG||Not vulnerable||Not vulnerable|
|3.4.xS||Not vulnerable||Vulnerable; migrate to 3.4.5S or later.|
|3.4.xSG||Not vulnerable||Not vulnerable|
|3.5.xS||Not vulnerable||Vulnerable; migrate to 3.7.2S or later.|
|3.6.xS||Not vulnerable||Vulnerable; migrate to 3.7.2S or later.|
|3.8.xS||Not vulnerable||Not vulnerable|
|3.9.xS||Not vulnerable||Not vulnerable|
Cisco IOS XR Software
Cisco IOS XR Software is not affected.
There are no workarounds for this vulnerability but there are mitigations that can be deployed on a general IP SLA responder to reduce the exposure to this vulnerability such as infrastructure access lists.
Conventional mitigation techniques such as IP SLA key chains or control plane protection are not an effective mitigation for this vulnerability.
For devices configured as general responders, mitigation techniques that can be deployed on Cisco devices within the network are available in the companion document "Identifying and Mitigating Exploitation of the Cisco IOS Software IP Service Level Agreement Vulnerability," which is available at http://tools.cisco.com/security/center/viewAMBAlert.x?alertId=27842.
Cisco has released free software updates that address the vulnerability described in this advisory. Prior to deploying software, customers are advised to consult their maintenance providers or check the software for feature set compatibility and known issues that are specific to their environments.
Customers may only install and expect support for feature sets they have purchased. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html.
Customers with Cisco products that are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers, should contact that organization for assistance with the appropriate course of action.
The effectiveness of any workaround or fix depends on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Because of the variety of affected products and releases, customers should consult their service providers or support organizations to ensure that any applied workaround or fix is the most appropriate in the intended network before it is deployed.
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC):
- +1 800 553 2447 (toll free from within North America)
- +1 408 526 7209 (toll call from anywhere in the world)
- e-mail: email@example.com
Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Customers without service contracts should request free upgrades through the TAC.
Refer to Cisco Worldwide Contacts at http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, instructions, and e-mail addresses for support in various languages.
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
This vulnerability was found during internal Cisco testing.gg
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.
This advisory is posted on Cisco Security at the following link:
Additionally, a text version of this advisory is clear signed with the Cisco PSIRT PGP key and circulated among the following e-mail addresses:
Future updates of this advisory, if any, will reside on Cisco.com but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.
|Revision 1.3||2013-April-12||Advisory republished to update metadata. The advisory content was not changed.|
|Revision 1.2||2013-March-28||Updated "Software Versions and Fixes" section, corrected software table.|
|Revision 1.1||2013-March-28||Updated "Details" section.|
|Revision 1.0||2013-March-27||Initial public release.|