29 March 2018
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.0902 Cisco IOS XE Software for Cisco Catalyst Switches IPv4 Denial of Service Vulnerability 29 March 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco Catalyst 3850 Cisco Catalyst 3650 Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2018-0177 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-ipv4 - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco Security Advisory Cisco IOS XE Software for Cisco Catalyst Switches IPv4 Denial of Service Vulnerability High Advisory ID: cisco-sa-20180328-ipv4 FirstÂ Published: 2018Â MarchÂ 28Â 16:00Â GMT VersionÂ 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvd80714 CVE-2018-0177 CWE-19 CVSSÂ Score: 8.6 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X Summary o A vulnerability in the IP Version 4 (IPv4) processing code of Cisco IOS XE Software running on Cisco Catalyst 3850 and Cisco Catalyst 3650 Series Switches could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to incorrect processing of certain IPv4 packets. An attacker could exploit this vulnerability by sending specific IPv4 packets to an IPv4 address on an affected device. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. If the switch does not reboot when under attack, it would require manual intervention to reload the device. 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-20180328-ipv4 This advisory is part of the March 28, 2018, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 20 Cisco Security Advisories that describe 22 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication. Affected Products o Vulnerable Products This vulnerability affects Cisco Catalyst 3850 and Cisco Catalyst 3650 Series Switches that are running Cisco IOS XE Software Release 16.1.1 or later, until the first fixed release, and are configured with an IPv4 address. For more information about which Cisco IOS XE Software releases are vulnerable, see the Fixed Software section of this advisory. 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. Products Confirmed Not Vulnerable No other Cisco products are currently known to be affected by this vulnerability. Cisco has confirmed that this vulnerability does not affect Cisco IOS Software, Cisco IOS XR Software, or Cisco NX-OS Software. Details o This vulnerability is triggered by certain IPv4 packets that are sent to an affected device. The same IPv4 packets that are sent through the device do not trigger this vulnerability. Indicators of Compromise o If an exploit has occurred, the device CPU usage will be high, as shown by the show process cpu sorted CLI command. Depending on the CPU usage, this information may be available only from a console connection, as remote VTY sessions may not be possible. Specifically, the IOSXE-RP Punt Se process will be the one that is consuming the CPU, as shown in the following example: Cat3850# show process cpu sorted | ex 0.00 CPU utilization for five seconds: 96%/66%; one minute: 61%; five minutes: 20% PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process 117 21796 90021 242 40.19% 21.51% 6.27% 0 IOSXE-RP Punt Se 203 153 6311 24 0.07% 0.04% 0.02% 0 IP ARP Retry Age 73 3448 1141 3021 0.07% 0.24% 0.55% 0 IOSD ipc task 200 174 6311 27 0.07% 0.05% 0.04% 0 IPAM Manager Cat3850# Workarounds o There are no workarounds that address this vulnerability. If the device has high CPU usage for the IOSXE-RP Punt Se process, try to identify the source of the IP traffic and prevent that address from sending the packets to the affected device, by either filtering the source address or removing the source device from the network. To recover the device, shut down the interface that the IPv4 packets are being received on, eliminate the source of the attack via an infrastructure access control list or other methods, and re-enable the interface. 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 This vulnerability is fixed in Cisco IOS XE Software Releases Denali 16.3.4, Everest 16.5.1a, Everest 16.5.2, Everest 16.6.1, and later. 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] 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 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. Subscribe to Cisco Security Notifications o Subscribe Related to This Advisory o Cisco Event Response: March 2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication Cisco Security Blog: Cisco IOS and IOS XE Software Bundled Publication March 2018 URL o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-ipv4 Revision History o +----------+----------------------------+----------+---------+----------------+ | Version | Description | Section | Status | Date | +----------+----------------------------+----------+---------+----------------+ | 1.0 | Initial public release. | -- | Final | 2018-March-28 | +----------+----------------------------+----------+---------+----------------+ - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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