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AUSCERT External Security Bulletin Redistribution
ESB-2018.0913.2
Cisco IOS and IOS XE Software Quality of Service Remote Code
Execution Vulnerability
16 April 2018
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS
Cisco IOS XE
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Increased Privileges -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2018-0151
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-qos
Revision History: April 16 2018: Update to revision 1.2
March 29 2018: Initial Release
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco Security Advisory
Cisco IOS and IOS XE Software Quality of Service Remote Code Execution
Vulnerability
Critical
Advisory ID: cisco-sa-20180328-qos
First Published: 2018 March 28 16:00 GMT
Last Updated: 2018 April 13 15:36 GMT
Version 1.2: Final
Workarounds: Yes
Cisco Bug IDs:
CSCvf73881
CVE-2018-0151
CWE-119
CVSSÂ Score:
9.8 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the quality of service (QoS) subsystem of Cisco IOS
Software and Cisco IOS XE Software could allow an unauthenticated, remote
attacker to cause a denial of service (DoS) condition or execute arbitrary
code with elevated privileges.
The vulnerability is due to incorrect bounds checking of certain values in
packets that are destined for UDP port 18999 of an affected device. An
attacker could exploit this vulnerability by sending malicious packets to
an affected device. When the packets are processed, an exploitable buffer
overflow condition may occur. A successful exploit could allow the attacker
to execute arbitrary code on the affected device with elevated privileges.
The attacker could also leverage this vulnerability to cause the device to
reload, causing a temporary DoS condition while the device is reloading.
The malicious packets must be destined to and processed by an affected
device. Traffic transiting a device will not trigger the vulnerability.
Cisco has released software updates that address this vulnerability. There
are workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-20180328-qos
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 devices that are running a vulnerable
release of Cisco IOS Software or Cisco IOS XE Software.
For information about which Cisco IOS and IOS XE Software releases are
vulnerable, see the Fixed Software section of this advisory.
Assessing a Device
To determine whether a device that is running Cisco IOS Software or
Cisco IOS XE Software may be affected by this vulnerability, administrators
can log in to the device and use the show udp command in the CLI.
The device may be affected by this vulnerability if the command returns
output similar to the following example:
Router> show udp
Proto Remote Port Local Port In Out Stat TTY OutputIF
17 0.0.0.0 0 --any-- 18999 0 0 11 0
The Adaptive QoS for Dynamic Multipoint VPN (DMVPN) feature of Cisco IOS
Software and Cisco IOS XE Software uses UDP port 18999 and may be open due
to the provisioning of this feature on unaffected platforms. If UDP port
18999 is bound to a listening port on a device, use the Cisco IOS Software
Checker to determine whether the device is running a vulnerable software
release.
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.
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 XR
Software or Cisco NX-OS Software.
Workarounds
o Customers who do not use the Adaptive QoS for DMVPN feature can deny all
traffic destined to UDP port 18999 on an affected device by using a Control
Plane Policing (CoPP) policy similar to the following:
! -- ACL for CoPP Undesireable UDP class-map
! -- Ignore fragments to prevent them from being misclassified by the policy
access-list 199 deny ip any any fragments
! -- Classify traffic destined to UDP Port 18999 so that we can drop it prior to being processed
access-list 199 permit udp any any eq 18999
! -- CoPP Undesireable UDP class-map
class-map match-all undesireable-udp
match access-group 199
! -- Undesireable UDP Policy Map
policy-map drop-udp
class undesireable-udp
drop
! -- Apply Undesireable UDP policy Map
control-plane
service-policy input drop-udp
On platforms that do not support the drop keyword within the Policy Map,
customers may consider utilizing a policy similar to the following as an
alternative:
! -- ACL for CoPP Undesirable UDP class-map
! -- Ignore fragments to prevent them from being misclassified by the policy
access-list 199 deny ip any any fragments
! -- Classify traffic destined to UDP Port 18999 so that we can drop it prior to being processed
access-list 199 permit udp any any eq 18999
! -- CoPP Undesireable UDP class-map
class-map match-all undesireable-udp
match access-group 199
! -- Undesireable UDP Policy Map - Drop on Police Rate
policy-map drop-udp
class undesireable-udp
police rate 8000
conform-action drop
exceed-action drop
violate-action drop
! -- Apply Undesireable UDP policy Map
control-plane
service-policy input drop-udp
If the Adaptive QoS for DMVPN feature is later configured, the device must
be upgraded to an unaffected release of Cisco IOS Software or Cisco IOS XE
Software and the CoPP policy must be removed.
Customers integrating this workaround into their environment are encouraged
to test the adaptation in their lab prior to deployment and to reference
the CoPP Best Practice Document at the following link: https://
www.cisco.com/c/en/us/about/security-center/copp-best-practices.html
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.
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
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 internal security testing.
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 46111
Cisco IOS and IOS XE Software Quality of Service Remote Code Execution
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-qos
Revision History
o
+---------+----------------------------+-------------+--------+---------------+
| Version | Description | Section | Status | Date |
+---------+----------------------------+-------------+--------+---------------+
| | Fixed typos in the | | | |
| | workarounds section; added | | | |
| 1.2 | comments to explain what | Workarounds | Final | 2018-April-13 |
| | the access-control lists | | | |
| | are doing. | | | |
+---------+----------------------------+-------------+--------+---------------+
| | Updated Workarounds | | | |
| | section with an updated | | | |
| | CoPP policy that includes | | | |
| | an additional Access-List | | | |
| | Entry addressing | | | |
| | fragmented packets that | | | |
| 1.1 | may have caused issues | Workarounds | Final | 2018-April-12 |
| | when integrated into | | | |
| | existing CoPP policies; | | | |
| | Alternative Policy Map for | | | |
| | platforms that do not | | | |
| | support the deny keyword | | | |
| | added. | | | |
+---------+----------------------------+-------------+--------+---------------+
| 1.0 | Initial public release. | -- | Final | 2018-March-28 |
+---------+----------------------------+-------------+--------+---------------+
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