Cisco Security Advisory
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AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
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Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. An attacker could exploit this vulnerability by sending a single DHCP packet to or through an affected device, causing the device to reload.
Cisco has released software updates that address this vulnerability. A workaround that mitigates this vulnerability is available. This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120926-dhcp
Note: The September 26, 2012, Cisco IOS Software Security Advisory bundled publication includes nine Cisco Security Advisories. Eight of the advisories address vulnerabilities in Cisco IOS Software, and one advisory addresses a vulnerability in Cisco Unified Communications Manager. 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 September 2012 bundled publication.
Individual publication links are in "Cisco Event Response: Semi-Annual Cisco IOS Software Security Advisory Bundled Publication" at the following link:
http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep12.html
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Vulnerable Products
Cisco devices that are running Cisco IOS Software versions that include the Device Sensor feature are affected by this vulnerability. Devices that have at least one interface with an IP address are affected.
To determine whether the Cisco IOS Software release includes the Device Sensor feature, issue the show subsys command.
The following example shows the Device Sensor feature is included:
To determine whether an interface is assigned an IP address, issue the show ip interface brief command.Switch#show subsys | include dsensor_lite dsensor_lite Protocol 1.000.001
The following example indicates the FastEthernet1/0 interface is assigned IP address 10.10.10.1:
router#show ip interface brief Interface IP-Address OK? Method Status Protocol FastEthernet1/0 10.10.10.1 YES manual up up FastEthernet1/1 unassigned YES NVRAM up up
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 truncatedAdditional 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.
Products Confirmed Not Vulnerable
Cisco IOS XE and Cisco IOS XR Software are not affected by this vulnerability.
No other Cisco products are currently known to be affected by this vulnerability.
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The Device Sensor feature of Cisco IOS Software is used to gather raw endpoint data from network devices that are using protocols such as Cisco Discovery Protocol, Link Layer Discovery Protocol (LLDP), and DHCP. The endpoint data is available to registered clients in the context of an access session.
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a DoS condition. An attacker could exploit this vulnerability by sending a single DHCP packet to or through an affected device, causing the device to reload.
The Device Sensor feature, enabled by default, is vulnerable on devices that have at least one interface with an IP address. The vulnerability is triggered when the Device Sensor feature attempts to process a DHCP packet. In affected releases, valid DHCP packets could trigger this vulnerability.
For more information about the Device Sensor feature, please refer to the Device Sensor Guide.
This vulnerability was previously documented in Cisco bug ID CSCty96049 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2012-4621.
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In affected releases, the Device Sensor feature is enabled by default. It is possible to mitigate the vulnerability in this advisory by applying the global configuration command device-sensor filter-spec dhcp exclude all. This command will filter the Device Sensor feature collection of DHCP packets, and the Device Sensor feature will no longer process or store DHCP information.
In the following example, the global configuration command is issued:
Switch# configure terminal Switch(config)# device-sensor filter-spec dhcp exclude all
To confirm that the Device Sensor feature is no longer collecting DHCP data, issue the show device-sensor cache all command. No DHCP entries should be present in the table.
In the following example, the following table contains only Cisco Discover Protocol data:
Switch# show device-sensor cache all Device: 000f.f7a7.234f on port GigabitEthernet2/1 -------------------------------------------------- Proto Type:Name Len Value cdp 22:mgmt-address-type 8 00 16 00 08 00 00 00 00 cdp 19:cos-type 5 00 13 00 05 00 cdp 18:trust-type 5 00 12 00 05 00 cdp 11:duplex-type 5 00 0B 00 05 01 cdp 10:native-vlan-type 6 00 0A 00 06 00 01 cdp 9:vtp-mgmt-domain-type 9 00 09 00 09 63 69 73 63 6F
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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 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 September 2012 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 https://sec.cloudapps.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 September 2012 Cisco IOS Software Security Advisory 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 September 2012 Cisco IOS Software Security Advisory 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 September 2012 Cisco IOS Software Security Advisory 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 September 2012 Cisco IOS Software Security Advisory 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 September 2012 Cisco IOS Software Security Advisory Bundled Publication 15.0EX Not vulnerable
Not vulnerable
15.0EY Not vulnerable
Not vulnerable
15.0M Not vulnerable
15.0(1)M9
15.0MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.0MRA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.0S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0(1)S6
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SE 15.0(1)SE3
15.0(2)SE
15.0(2)SE1; Available on 10-DEC-12
15.0(2)SE15.0SG Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.0(2)SG5
15.0(2)SG6 ; Available on 11-OCT-12
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SY Not vulnerable
15.0(1)SY2
15.0XA Not vulnerable
Vulnerable; First fixed in Release 15.1M
15.0XO Cisco IOS XE devices: Please see Cisco IOS-XE Software Availability
Cisco IOS XE devices: Please see Cisco IOS-XE Software AvailabilityAffected 15.1-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication 15.1EY Not vulnerable
15.1(2)EY4
15.1GC Not vulnerable
Vulnerable; First fixed in Release 15.1M
15.1M Not vulnerable
15.1(4)M5
15.1MR Not vulnerable
15.1(3)MR; Available on 01-OCT-12
15.1S Not vulnerable
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(3)S
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.1SG 15.1(1)SG1
15.1(2)SG; Available on 12-NOV-12
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(1)SG1
15.1(2)SG 12-NOV-12
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.1SNG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SNH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SNI Not vulnerable
Vulnerable; migrate to any release in 15.2SNG
15.1SV 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.
15.1T Not vulnerable
Vulnerable; First fixed in Release 15.1M
15.1XB Not vulnerable
Vulnerable; First fixed in Release 15.1M
Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication 15.2GC Not vulnerable
Releases prior to 15.2(3)GC are vulnerable; Releases 15.2(3)GC and later are not vulnerable. First fixed in Release 15.2T
15.2JA Not vulnerable
Not Vulnerable
15.2M Not vulnerable
Not vulnerable15.2S 15.2(2)S1
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.2(1)S2
15.2(2)S1
15.2(4)S
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.2SNG Not vulnerable
Not vulnerable
15.2T Not vulnerable
15.2(1)T3
15.2(2)T2
15.2(3)T2; Available on 12-OCT-12
Cisco IOS XE SoftwareCisco IOS XE Software is not affected by this vulnerability.
Cisco IOS XR Software
Cisco IOS XR Software is not affected by this vulnerability.
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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 the troubleshooting of customer service requests.
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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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Show LessRevision 1.0 2012-September-26 Initial public release.
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