24 March 2016
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2016.0784 Cisco IOS and IOS XE Software Smart Install Denial of Service Vulnerability 24 March 2016 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS Cisco IOS XE Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2016-1349 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160323-smi - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco Security Advisory Cisco IOS and IOS XE Software Smart Install Denial of Service Vulnerability High Advisory ID: cisco-sa-20160323-smi Published: 2016 March 23 16:00 GMT Version 1.0: Final CVSS Score: Base - 7.8 Workarounds: No workarounds available Cisco Bug IDs: CSCuv45410 CVE-2016-1349 CWE-399 Summary The Smart Install client feature in Cisco IOS and IOS XE Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to incorrect handling of image list parameters. An attacker could exploit this vulnerability by sending crafted Smart Install packets to TCP port 4786. A successful exploit could cause a Cisco Catalyst switch to reload, resulting in a DoS condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability other than disabling Smart Install functionality on the vulnerable device. This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160323-smi This advisory is part of the March 23, 2016, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes six Cisco Security Advisories that describe six vulnerabilities. All the vulnerabilities have a Security Impact Rating of "High." For a complete list of advisories and links to them, see Cisco Event Response: Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication. Affected Products The Smart Install client feature in Cisco IOS and IOS XE Software is a plug-and-play configuration and image-management feature that provides zero-touch deployment for new switches. The feature allows a customer to ship a Cisco switch to any location, install it in the network, and power it on without additional configuration requirements. Vulnerable Products This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS or IOS XE Software with the Smart Install client feature enabled. For information about which Cisco IOS and IOS XE Software releases are vulnerable, see the "Fixed Software" section of this advisory. To determine whether a Cisco IOS or IOS XE device is configured with the Smart Install client feature enabled, use the show vstack config privileged EXEC command on the Smart Install client. The following is the output of the show vstack config command in a Cisco Catalyst Switch configured as a Smart Install client. The output for Role: Client from the show vstack config command confirms that the feature is enabled on the device. Indicators of Compromise Exploitation of this vulnerability will cause an affected device to reload and generate a crashinfo file. Contact the Cisco Technical Assistance Center (TAC) to review the file and determine whether the device has been compromised by exploitation of this vulnerability. Workarounds There are no workarounds available that address this vulnerability other than disabling the Smart Install feature. The Smart Install Feature is enabled by default on client switches. No configuration is needed in the client switches. In certain releases of Cisco IOS and IOS XE Software, the Smart Install client feature can be disabled with the global configuration command no vstack. In certain releases of Cisco IOS and IOS XE Software where the command is available, the vulnerability can be addressed by disabling the Smart Install client feature. The following example shows the output of the show vstack config command in a Cisco Catalyst Switch with the Smart Install client feature disabled: switch#show vstack config Role: Client (SmartInstall disabled) Vstack Director IP address: 10.1.1.100 Note: The no vstack global configuration command to disable the Smart Install client feature was introduced with the fix for Cisco bug CSCtj75729 (Ability to shut Smart Install default service on TCP port 4786). If a Cisco IOS or IOS XE Software release supports the Smart Install client feature but the no vstack command does not exist, the release does not contain the fix for Cisco bug CSCtj75729. Fixed Software Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license: http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades. When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses 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 upgrade 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. Customers Without Service Contracts 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): http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html 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. Cisco IOS and IOS XE Software To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides a tool, the Cisco IOS Software Checker, that identifies any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory ("First Fixed"). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified ("Combined First Fixed"). Customers can use this tool to perform the following tasks: Initiate a search by choosing one or more releases from a drop-down menu or uploading a file from a local system for the tool to parse Enter the output of the show version command for the tool to parse Create a custom search by including all previously published Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication To determine whether a release is affected by any published Cisco Security Advisory, use the Cisco IOS Software Checker on Cisco.com or enter a Cisco IOS or IOS XE Software releasefor example, 15.1(4)M2 or 3.01.4Sin the following field: Check For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the Cisco IOS XE Software release. Exploitation and Public Announcements 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. Source This vulnerability was found and reported to Cisco by Tenable Network Security. URL http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160323-smi Revision History Version Description Section Status Date 1.0 Initial public release. Final 2016-March-23 Legal Disclaimer 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 standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to email@example.com and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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