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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.0100 Cisco IOS and IOS XE Software Secure Shell Connection on VRF Vulnerability 11 January 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS Cisco IOS XE Publisher: Cisco Systems Operating System: Cisco Impact/Access: Reduced Security -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2018-0484 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190109-ios-ssh-vrf - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco IOS and IOS XE Software Secure Shell Connection on VRF Vulnerability Priority: Medium Advisory ID: cisco-sa-20190109-ios-ssh-vrf First Published: 2019 January 9 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvk37852 CVSS Score: Base 5.3 CVSS: 3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:X/RL:X/RC:X CVE-2018-0484 CWE-284 Summary o A vulnerability in the access control logic of the Secure Shell (SSH) server of Cisco IOS and IOS XE Software may allow connections sourced from a virtual routing and forwarding (VRF) instance despite the absence of the vrf-also keyword in the access-class configuration. The vulnerability is due to a missing check in the SSH server. An attacker could use this vulnerability to open an SSH connection to an affected Cisco IOS or IOS XE device with a source address belonging to a VRF instance. Once connected, the attacker would still need to provide valid credentials to access the device. 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-20190109-ios-ssh-vrf Affected Products o Vulnerable Products This vulnerability affects Cisco IOS and Cisco IOS XE Software. For information about which software releases are vulnerable, see the Fixed Software section of this advisory. Products Confirmed Not Vulnerable Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability. Determining the Cisco IOS Software Release To determine which Cisco IOS Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS Software, the system banner displays text similar to Cisco Internetwork Operating System Software or Cisco IOS Software. The banner also displays the installed image name in parentheses, followed by the Cisco IOS Software release number and release name. Some Cisco devices do not support the show version command or may provide different output. The following example shows the output of the command for a device that is running Cisco IOS Software Release 15.5(2)T1 and has an installed image name of C2951-UNIVERSALK9-M: Router> show version Cisco IOS Software, C2951 Software (C2951-UNIVERSALK9-M), Version 15.5(2)T1, RELEASE SOFTWARE (fc1) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2015 by Cisco Systems, Inc. Compiled Mon 22-Jun-15 09:32 by prod_rel_team . . . For information about the naming and numbering conventions for Cisco IOS Software releases, see the Cisco IOS and NX-OS Software Reference Guide. Determining the Cisco IOS XE Software Release To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS Software, Cisco IOS XE Software, or similar text. The following example shows the output of the command for a device that is running Cisco IOS XE Software Release 16.2.1 and has an installed image name of CAT3K_CAA-UNIVERSALK9-M: ios-xe-device# show version Cisco IOS Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version Denali 16.2.1, RELEASE SOFTWARE (fc1) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2016 by Cisco Systems, Inc. Compiled Sun 27-Mar-16 21:47 by mcpre . . . For information about the naming and numbering conventions for Cisco IOS XE Software releases, see the Cisco IOS and NX-OS Software Reference Guide. Workarounds o There are no workarounds that address this vulnerability. Fixed Software o For detailed information about affected and fixed software releases, consult the Cisco IOS Software Checker. 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. 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 list 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 Software or Cisco IOS XE Software release--for example, 15.1(4)M2 or 3.13.8S--in the following field: [ ] [Check] By default, the Cisco IOS Software Checker includes results only for vulnerabilities that have a Critical or High Security Impact Rating (SIR). To include results for Medium SIR vulnerabilities, use the Cisco IOS Software Checker on Cisco.com and check the Medium check box in the Impact Rating drop-down list. 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. URL o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190109-ios-ssh-vrf Revision History +----------+---------------------------+----------+--------+------------------+ | Version | Description | Section | Status | Date | +----------+---------------------------+----------+--------+------------------+ | 1.0 | Initial public release. | -- | Final | 2019-January-09 | +----------+---------------------------+----------+--------+------------------+ Legal Disclaimer o 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 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. 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