Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.0421 Cisco IOS XR Software Intermediate System-to-Intermediate System DoS Vulnerability 5 February 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS XR Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2019-16027 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20200122-ios-xr-dos - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco IOS XR Software Intermediate System-to-Intermediate System Denial of Service Vulnerability Priority: High Advisory ID: cisco-sa-20200122-ios-xr-dos First Published: 2020 January 22 16:00 GMT Last Updated: 2020 February 4 18:33 GMT Version 1.1: Final Workarounds: No workarounds availableCisco Bug IDs: CSCvr62342 CVE-2019-16027 CWE-20 CVSS Score: 7.7 AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X Summary o A vulnerability in the implementation of the Intermediate System-to-Intermediate System (IS-IS) routing protocol functionality in Cisco IOS XR Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition in the IS-IS process. The vulnerability is due to improper handling of a Simple Network Management Protocol (SNMP) request for specific Object Identifiers (OIDs) by the IS-IS process. An attacker could exploit this vulnerability by sending a crafted SNMP request to the affected device. A successful exploit could allow the attacker to cause a DoS condition in the IS-IS process. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20200122-ios-xr-dos Affected Products o Vulnerable Products This vulnerability affects Cisco devices if they are running Cisco IOS XR Software releases earlier than 6.6.3, 7.0.2, 7.1.1, or 7.2.1 and they configured with both the IS-IS routing protocol and SNMP versions 1, 2c, or 3. Cisco has confirmed that this vulnerability affects both Cisco IOS XR 32-bit Software and Cisco IOS XR 64-bit Software. Determine Whether the Device Has a Vulnerable Configuration To determine if the device is configured for IS-IS routing, administrators can use the show running-config router isis EXEC command in the CLI. If the device is configured for IS-IS routing, this command will return output. The following example shows the partial output of the show running-config router isis command on a device that is configured for IS-IS routing. #show running-config router isis router isis {isp} is-type level-2-only ... To determine if the device is configured for SNMP, administrators can use the show running-config snmp EXEC command in the CLI. If the device is configured for SNMP, this command will return output. The following examples show the partial output of the show running-config snmp command on a device that is configured for SNMP. Only one version of SNMP needs to be configured for the device to be vulnerable. The vulnerability is triggered through an SNMP query, but the configuration can be for read or write. SNMPv1 #show running-config snmp snmp-server community {public ro} ... SNMPv2 #show running-config snmp snmp-server group {SNMP_GROUP1} v2c ... SNMPv3 #show running-config snmp snmp-server view {SNMP_VIEW1 1.3.6.1.2.1.1.5 included} snmp-server group {SNMP_GROUP1} v3 {auth read SNMP_VIEW1} ... Products Confirmed Not Vulnerable Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability. Cisco has confirmed that this vulnerability does not affect the following Cisco products: Cisco IOS and IOS XE Software Cisco IOS XR7-LNT Software Cisco NX-OS Software Workarounds o There are no workarounds that address this vulnerability. However, administrators may choose to perform one of the following mitigations: Disable SNMP: This vulnerability is exploited by doing an SNMP query of a special MIB OID range. If SNMP is disabled, this vulnerability cannot be exploited. For mitigation of this vulnerability if SNMP is enabled on the device, contact Cisco TAC for assistance with the OIDs. Configure an access control list: Administrators can also configure an access control list (ACL) on an SNMP community to filter incoming SNMP requests to ensure that SNMP queries are performed only by trusted SNMP clients. For information about configuring ACLs, see the Cisco Guide to Harden Cisco IOS XR Devices . Fixed Software o 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: https://www.cisco.com/c/en/us/products/end-user-license-agreement.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 regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page , 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. 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 TAC: https://www.cisco.com/c/en/us/support/web/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. Fixed Releases Cisco fixed this vulnerability in Cisco IOS XR Software Release 6.6.3. Cisco also plans to fix this vulnerability in Cisco IOS XR Software releases 7.0.2, 7.1.1, and 7.2.1. Customers are advised to install the appropriate SMU as shown in the following table. Customers who require SMUs for other platforms and releases are advised to contact their support organization. IOS XR Release Platform SMU Name 4.3.2 XR12000 c12k-4.3.2.CSCvr62342 5.2.5 NCS6K ncs6k-5.2.5.CSCvr62342 6.1.3 ASR9K-PX asr9k-px-6.1.3.CSCvr62342 6.1.3 NCS5K ncs5k-6.1.3.CSCvr62342 6.1.3 NCS5500 ncs5500-6.1.3.CSCvr62342 6.1.4 ASR9K-PX asr9k-px-6.1.4.CSCvr6234 6.1.4 CRS-PX hfr-px-6.1.4.CSCvr62342 6.1.4 NCS5500 ncs5500-6.1.4.CSCvr62342 6.1.4 NCS5K ncs5k-6.1.4.CSCvr62342 6.1.4 XRV9K xrv9k-6.1.4.CSCvr62342 6.2.25 NCS5K ncs5k-6.2.25.CSCvr62342 6.2.3 NCS5K ncs5k-6.2.3.CSCvr62342 6.2.3 ASR9K-PX asr9k-px-6.2.3.CSCvr62342 6.2.3 ASR9K-X64 asr9k-x64-6.2.3.CSCvr62342 6.2.3 CRS-PX hfr-px-6.2.3.CSCvr62342 6.2.3 NCS5500 ncs5500-6.2.3.CSCvr62342 6.2.3 XRV9K xrv9k-6.2.3.CSCvr62342 6.2.3 NCS6K ncs6k-6.2.3.CSCvr62342 6.3.15 NCS5500 ncs5500-6.3.15.CSCvr62342 6.3.2 ASR9K-PX asr9k-px-6.3.2.CSCvr62342 6.3.2 ASR9K-X64 asr9k-x64-6.3.2.CSCvr62342 6.3.3 ASR9K-X64 asr9k-x64-6.3.3.CSCvr62342 6.3.3 ASR9K-PX asr9k-px-6.3.3.CSCvr62342 6.3.3 NCS5K ncs5k-6.3.3.CSCvr62342 6.3.3 NCS540 ncs540-6.3.3.CSCvr62342 6.3.3 NCS5500 ncs5500-6.3.3.CSCvr62342 6.3.3 NCS6K 6.4.2 ASR9K-PX asr9k-px-6.4.2.CSCvr62342 6.4.2 ASR9K-X64 asr9k-x64-6.4.2.CSCvr62342 6.4.2 CRS-PX hfr-px-6.4.2.CSCvr62342 6.4.2 NCS5K ncs5k-6.4.2.CSCvr62342 6.4.2 NCS6K ncs6k-6.4.2.CSCvr62342 6.4.2 XRV9K xrv9k-6.4.2.CSCvr62342 6.5.2 ASR9K-PX asr9k-px-6.5.2.CSCvr62342 6.5.2 ASR9K-X64 asr9k-x64-6.5.2.CSCvr62342 6.5.2 NCS5K ncs5k-6.5.2.CSCvr62342 6.5.2 NCS5500 ncs5500-6.5.2.CSCvr62342 6.5.3 ASR9K-X64 asr9k-x64-6.5.3.CSCvr62342 6.5.3 NCS5500 ncs5500-6.5.3.CSCvr62342 6.5.3 NCS540 ncs540-6.5.3.CSCvr62342 6.5.3 NCS5K ncs5k-6.5.3.CSCvr62342 6.5.3 ASR9K-PX asr9k-px-6.5.3.CSCvr62342 6.5.3 NCS560 6.5.3 XRV9K xrv9k-6.5.3.CSCvr62342 6.6.1 NCS5500 ncs5500-6.6.1.CSCvr62342 6.6.2 ASR9K-PX asr9k-px-6.6.2.CSCvr62342 6.6.2 ASR9K-X64 asr9k-x64-6.6.2.CSCvr62342 6.6.25 NCS5500 ncs5500-6.6.25.CSCvr62342 6.6.25 NCS540 ncs540-6.6.25.CSCvr62342 6.6.25 NCS560 ncs560-6.6.25.CSCvr62342 To download the SMUs from the Software Center on Cisco.com , do the following: 1. Click Browse All . 2. Choose IOS and NX-OS Software > IOS XR > IOS XR Software > Optical Networking or Routers . 3. Choose a specific product and model from the right pane of the product selector. 4. Choose a release from the left pane of the product page. Exploitation and Public Announcements o 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 o This vulnerability was found during the resolution of a Cisco TAC support case. Cisco Security Vulnerability Policy o 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. Action Links for This Advisory o Snort Rule 52645 Snort Rule 52646 Snort Rule 52647 Snort Rule 52648 Snort Rule 52649 URL o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20200122-ios-xr-dos Revision History o +---------+---------------------+-------------+--------+------------------+ | Version | Description | Section | Status | Date | +---------+---------------------+-------------+--------+------------------+ | | Changed en dashes | Title, | | | | | to hyphens | Summary, | | | | 1.1 | throughout. No | and | Final | 2020-February-04 | | | content changes | Vulnerable | | | | | were made. | Products. | | | +---------+---------------------+-------------+--------+------------------+ | 1.0 | Initial public | - | Final | 2020-January-22 | | | release. | | | | +---------+---------------------+-------------+--------+------------------+ - --------------------------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 auscert@auscert.org.au 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. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXjpd12aOgq3Tt24GAQhXnw/7B/m3V6H7FcazwwUrj/k2+HOGzkfmu1BW j+HD9+Xp2HCJSXZCyMoKReN5GZ4SfwK/8DjyVqIkm9kJud34+SVT8gju1u5qmHTW aN/Ii7lmbAg9Hy3+p6lQ3AbAtKe529c1yvXVWZKLXhYRY6oXC9gs3IBb0ro+imyo zpn6GjvsYvo6mndY11cUblC3z6iAJgVIhgiMFV2y39JgOef5c40c0iYFzlLF6wmi qn7md9MxzDSats6CaV+ZEAsTPdVUgnkDP+Oi9UZH1AKnmNaLLXhzwcxDbiaN2TNC r26X3+jWVo+R5d2/u/e7yYLehb6lirnI6hsD74+jCWVzjsNK0Z7TM3qnFqcS+E1q mnnK41PNtHK5mHHsiOwCdB3U0iMKI6phK5GfgdYOkMSXjXTdChkoLHmvMSYqWg9y i5Yk4mB+ntlEd6giom9egCiLzAg+EQzmQBM6Luj4QIyWyUpDBCBZhezMCvA8lXx/ lYjuSdOB8PkwMH2dsa2dAll9ikZcaZuSoJJjZSTW2UfoTj8o+V9wUg/UZ7/6Ibev 0IyKjnjU7o3IN18RfaBEnIlveJ0Str55Dkwg0nPuR9/VCC+GWjhAX9dFo7j3UqZQ eYRXS3FyFws5rD/hRIRQvDrGI77S/4d8wRvIV8a6ybw2Ulg6WOVNyKY7fW0+Mb8A iH6TB718Fxs= =qdQ3 -----END PGP SIGNATURE-----