AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
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A vulnerability in the T1/E1 driver queue implementation of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an interface wedge condition, which could lead to loss of connectivity, loss of routing protocol adjacency, and could result in a denial of service (DoS) scenario.
The vulnerability is due to incorrect implementation of the T1/E1 driver queue. An attacker could exploit this vulnerability by sending bursty traffic through the affected interface driver. Repeated exploitation could cause a DoS condition.
Workarounds to mitigate this vulnerability are available.
Cisco has released software updates that address this vulnerability. This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-wedge
Note: The September 25, 2013, Cisco IOS Software Security Advisory bundled publication includes eight 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 September 2013 bundled publication.
Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Security Advisory Bundled Publication" at the following link:
http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep13.html
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Vulnerable Products
Cisco devices running affected Cisco IOS Software versions configured with T1/E1 interface module signaling are vulnerable.
A device is vulnerable if all the following criteria are met:
- An interface controller configured for T1/E1 channel group is using the affected High-Level Data Link Control 32 (HDLC32) driver.
- T1/E1 controller clock source is configured for line or internal
Note: The affected HDLC32 driver is only used on VWIC2 interface cards for Cisco 1900, 2900 and 3900 Series Integrated Services Routers (ISR).
To determine whether a Cisco IOS device is configured with T1/E1 signaling on a controller using HDLC32 driver, issue the show controllers command.
The following example shows a Cisco IOS device that is affected by this vulnerability. The device is vulnerable because the interface Serial0/0/0, configured for T1 signaling is using an HDLC32 driver as indicated by the “Hardware is HDLC32” output:
Router#show controllers Serial0/0/0:0
Interface Serial0/0/0:0
Hardware is HDLC32
< output truncated >
To determine a clock source type configured on a T1/E1 interface on a Cisco IOS device, issue the show controllers T1/E1 command.
The following example shows an E1 interface on a Cisco IOS device configured with line clock source:
Router#show controllers e1
E1 0 is up.
Applique type is Channelized E1 - balanced
!--- output truncated
Framing is CRC4, Line Code is HDB3, Clock Source is Line Primary.
!--- output truncatedTo 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.
Products Confirmed Not Vulnerable
Cisco IOS XR software is not affected by the vulnerability disclosed in this advisory.
No other Cisco products are currently known to be affected by this vulnerability.
Cisco IOS XE software is not affected by the vulnerability disclosed in this advisory.
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A vulnerability in the T1/E1 driver queue implementation of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an interface wedge condition, which could lead to loss of connectivity, loss of routing protocol adjacency, and could result in a denial of service (DoS) scenario.
The vulnerability is due to incorrect implementation of the T1/E1 driver queue. An attacker could exploit this vulnerability by sending bursty traffic through the affected interface driver. Repeated exploitation could cause a DoS condition.
A device is vulnerable if it is configured with T1/E1 signaling on an interface that is using an HDLC32 driver.
An attacker with some knowledge of the affected infrastructure could exploit this vulnerability by sending a bursty profile of network packets through vulnerable devices. Successful exploitation of the vulnerability could allow an attacker to wedge the transmit queue of an egress interface.
Workarounds to mitigate this vulnerability are available.
Valid network traffic could trigger this vulnerability on devices that are considered vulnerable. An attacker could send an bursty profile of network packets egressing an interface with set conditions to exploit this vulnerability. Recovery from this interface queue wedge requires a reload of the device.
An interface queue wedge is a class of vulnerability where certain packets are received and queued by a Cisco IOS router or switch but, due to a processing error, are never removed from the queue.
For more information about queue wedges and a few detection mechanisms that may be used to identify a blocked interface on Cisco IOS Software (including a white paper describing how this condition can be detected using SNMP) see http://blogs.cisco.com/security/comments/cisco_ios_queue_wedges_explained/.
This vulnerability has been documented in Cisco bug ID CSCub67465 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2013-5477.
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If a hardware upgrade is an option, a possible workaround would be to use VWIC3-T1/E1 or HWIC-T1/E1 interface cards instead of the VWIC2 interface card.
Alternatively, if the T1/E1 controller is configured for clock source line, and only a single channel-group is configured under controller, a possible workaround is to configure clock source line independent.The following identification mechanism exist for this vulnerability.
Embedded Event Manager (EEM)
A Cisco IOS Embedded Event Manager (EEM) policy that is based on Tool Command Language (Tcl) can be used on vulnerable Cisco IOS devices to identify and detect an interface queue wedge that is caused by this vulnerability. The policy allows administrators to monitor the interfaces for Cisco IOS devices and detect when the interface input queues are full. When Cisco IOS EEM detects potential exploitation of this vulnerability, the policy can trigger a response by sending an alert to the network administrator, who could then decide to implement an upgrade, implement suitable mitigations or reload the device to clear the input queue.
The Tcl script is available for download at the "Cisco Beyond: Embedded Event Manager (EEM) Scripting Community" at the following link: https://supportforums.cisco.com/docs/DOC-19337
The Cisco Security blog "Cisco IOS Queue Wedges Explained" can be viewed at the following link: http://blogs.cisco.com/security/cisco_ios_queue_wedges_explained/
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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 September 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 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 2013 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 2013 Cisco IOS Software Security Advisory Bundled Publication 12.2EX Not vulnerable
Vulnerable; First fixed in Release 15.0SE
12.2EY Not vulnerable
Vulnerable; First fixed in Release 15.2S
12.2EZ Not vulnerable
Releases prior to 12.2(60)EZ2 are vulnerable; Releases 12.2(60)EZ2 and later are not vulnerable. First fixed in Release 15.0SE
12.2IRB Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2IRC Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2IRD Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2IRE Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2IRF Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2IRG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2IRH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2IRI Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2IXG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2IXH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2MC Not vulnerable
Vulnerable; First fixed in Release 15.1M
12.2MRA Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2MRB Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SB Not vulnerable
12.2(33)SB15
12.2SCA Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCB Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCC Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCD Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCE Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCF Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCG Not vulnerable
Vulnerable; First fixed in Release 12.2SCH
12.2SCH Not vulnerable
12.2(33)SCH1
12.2SE Not vulnerable
12.2(55)SE8
12.2SEG Not vulnerable
Vulnerable; First fixed in Release 15.0SE
12.2SG Not vulnerable
12.2(53)SG10; available December 2013 *
12.2SGA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SM Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SQ Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SRA Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2SRB Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2SRC Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2SRD Not vulnerable
Vulnerable; First fixed in Release 12.2SRE
12.2SRE Not vulnerable
12.2(33)SRE9
12.2STE Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SV Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SVD Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SVE Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SW Not vulnerable
Vulnerable; First fixed in Release 15.1M
12.2SXF Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SXH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2SXI Not vulnerable
12.2(33)SXI12
12.2SXJ Not vulnerable
12.2(33)SXJ6
12.2SY Not vulnerable
Vulnerable; First fixed in Release 15.0SY
12.2WO Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2XNA Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XNB Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XNC Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XND Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XNE Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XNF Please see Cisco IOS XE Software Availability
Please see Cisco IOS XE Software Availability
12.2XO Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
12.2ZYA Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
Affected 12.3-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 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 2013 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 2013 Cisco IOS Software Security Advisory Bundled Publication 15.0EA Not vulnerable
15.0(2)EA1
15.0EB Not vulnerable
Vulnerable; migrate to any release in 15.2E
15.0EC Not vulnerable
Vulnerable; migrate to any release in 15.2E
15.0ED Not vulnerable
Note: Releases prior to 15.0(2)ED1 are vulnerable; Releases 15.0(2)ED1 and later are not vulnerable.
15.0EH Not vulnerable
Not vulnerable
15.0EJ Not vulnerable
Not vulnerable
15.0EX Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0EY Not vulnerable
15.0(2)EY2
15.0EZ Not vulnerable
Only Release 15.0(2)EZ is vulnerable15.0M Vulnerable; First fixed in Release 15.1M
Vulnerable; First fixed in Release 15.1M
15.0MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.0S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
Vulnerable; First fixed in Release 15.1S
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SE Not vulnerable
15.0(2)SE4
15.0SG 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.
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SQA Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SQB Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.0SY Not vulnerable
15.0(1)SY5
15.0XA Vulnerable; First fixed in Release 15.1M
Vulnerable; First fixed in Release 15.1M
15.0XO Not vulnerable
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.
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 2013 Cisco IOS Software Security Advisory Bundled Publication 15.1EY Not vulnerable
Vulnerable; First fixed in Release 15.2S
15.1GC Vulnerable; First fixed in Release 15.1M
Vulnerable; First fixed in Release 15.1M
15.1M 15.1(4)M7
15.1(4)M7
15.1MR Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1MRA Not vulnerable
15.1(3)MRA2
15.1S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(3)S6
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.1SG Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.1(2)SG1
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; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.1SVD Not vulnerable
Not vulnerable
15.1SVE Not vulnerable
Not vulnerable
15.1SVF Not vulnerable
Not vulnerable
15.1SY Not vulnerable
15.1(1)SY2; Available on 28-OCT-13
15.1(2)SY15.1T Vulnerable; First fixed in Release 15.1M
Vulnerable; First fixed in Release 15.1M
15.1XO Not vulnerable
Not vulnerable
Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication 15.2E Not vulnerable
Not vulnerable
15.2GC 15.2(4)GC
Vulnerable; migrate to any release in 15.4T
15.2JA 15.2(4)JA1
15.2(4)JA1
15.2JAX 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.
15.2JB 15.2(2)JB2
15.2(2)JB2
15.2JN Not vulnerable
Not vulnerable
15.2M 15.2(4)M3
15.2(4)M4
15.2S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.2(4)S4
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.2SA Not vulnerable
15.2(2)SA
15.2SNG Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.2SNH Not vulnerable
Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
15.2SNI Not vulnerable
Vulnerable; First fixed in Release 15.3S
15.2T 15.2(2)T4
15.2(3)T4
15.2(3)T4
Affected 15.3-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication 15.3M Not vulnerable
Not vulnerable
15.3S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
15.3(2)S2
15.3(3)S
Cisco IOS XE devices: Please see Cisco IOS XE Software Availability15.3T 15.3(1)T2
15.3(2)T
15.3(1)T2
15.3(2)T1
* Cisco Catalyst 4500 Series Switches with Cisco Catalyst 4500 Supervisor Engines 6-E or 6L-E can migrate to Cisco IOS Software Release 15.1SG.
Cisco IOS XR Software
Cisco IOS XR Software is not affected by any of the vulnerabilities that are disclosed in the September 2013 Cisco IOS Software Security Advisory Bundled Publication.
Cisco IOS XE Software
Cisco IOS XE Software is not affected by the vulnerability disclosed in this advisory.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, and Cisco IOS XE 3SG Release Notes.
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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 discovered during resolution of a support case.
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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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Revision 1.0 2013-September-25 Initial public release
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