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AUSCERT External Security Bulletin Redistribution
ESB-2018.0918
Cisco IOS XE Software Switch Integrated Security Features
IPv6 Denial of Service Vulnerability
29 March 2018
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2018-0164
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-sisf
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Cisco Security Advisory
Cisco IOS XE Software Switch Integrated Security Features IPv6 Denial of
Service Vulnerability
Medium
Advisory ID: cisco-sa-20180328-sisf
First Published: 2018 March 28 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs:
CSCvd75185
CVE-2018-0164
CWE-399
CVSSÂ Score:
6.8 AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the Switch Integrated Security Features of Cisco IOS XE
Software could allow an unauthenticated, remote attacker to cause an
interface queue wedge.
The vulnerability is due to incorrect handling of crafted IPv6 packets. An
attacker could exploit this vulnerability by sending crafted IPv6 packets
through the device. An exploit could allow the attacker to cause an
interface queue wedge.
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-sisf
Affected Products
o Vulnerable Products
This vulnerability affects the Cisco cBR-8 Converged Broadband Router,
Cisco ASR 1000 Series Aggregation Services Routers, and Cisco Cloud
Services Router 1000V Series when configured with IPv6.
In the field and internal testing, this vulnerability was only observed or
reproduced on the Cisco cBR-8 Converged Broadband Router. The Cisco ASR
1000 Series Aggregation Services Routers and Cisco Cloud Services Router
1000V Series contain the same code logic, so affected trains have had the
code fix applied; however, on these two products, the vulnerability has not
been observed in the field or successfully reproduced internally.
For information about which Cisco IOS XE Software releases are vulnerable,
consult the Cisco bug ID(s) at the top of this advisory.
Assessing the IPv6 Configuration
Administrators can identify interfaces that have assigned IPv6 addresses by
using the show ipv6 interface brief command in the CLI. The following
example shows the output of the command on a device with IPv6 enabled:
router#show ipv6 interface brief
.
.
.
GigabitEthernet0/0/0 [Up/Up]
fe80::212:daff:fe62:c150
2001:DB8::1
If IPv6 is not supported by the software release that is running on a
device, using the show ipv6 interface brief command produces an error
message. If IPv6 is not enabled on the device, using the show ipv6
interface brief command does not show any interfaces with IPv6 addresses.
In either scenario, the device is not affected by this vulnerability.
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.
Indicators of Compromise
o If an interface is queue wedged an admin could observe the input queue via
the show interface | include Input queue CLI command. The following example
shows the second interface on the router as wedged:
Router#show interface | include Input queue
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Input queue: 376/375/0/0 (size/max/drops/flushes); Total output drops: 0
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Router#
Once the identified interface is known, capture the output of the show
buffers input-interface [interface] packet and show buffers input-interface
[interface] dump CLI commands and contact your local support organization.
Workarounds
o There are no workarounds that address this vulnerability. However, it is
possible to increase the input queue to a higher value until the source of
the issue is identified or the device is upgraded.
Fixed Software
o For detailed information about fixed software releases, consult the Cisco
bug ID(s) at the top of this advisory.
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.
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.
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
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-sisf
Revision History
o
+----------+----------------------------+----------+---------+----------------+
| Version | Description | Section | Status | Date |
+----------+----------------------------+----------+---------+----------------+
| 1.0 | Initial public release. | -- | Final | 2018-March-28 |
+----------+----------------------------+----------+---------+----------------+
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