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AUSCERT External Security Bulletin Redistribution
Cisco IOS and IOS XE and Cisco Unified Communications Manager Software
Session Initiation Protocol Memory Leak Vulnerability
24 March 2016
AusCERT Security Bulletin Summary
Product: Cisco Unified Communications Manager
Cisco IOS XE
Publisher: Cisco Systems
Operating System: Cisco
VMware ESX Server
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2016-1350
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Cisco Security Advisory
Cisco IOS and IOS XE and Cisco Unified Communications Manager Software Session
Initiation Protocol Memory Leak Vulnerability
Advisory ID: cisco-sa-20160323-sip
Published: 2016 March 23 18:30 GMT
Version 1.0: Final
Base - 7.8
No workarounds available
Cisco Bug IDs:
A vulnerability in the Session Initiation Protocol (SIP) gateway
implementation in Cisco IOS, IOS XE, and Cisco Unified Communications Manager
Software could allow an unauthenticated, remote attacker to cause a memory
leak and eventual reload of an affected device.
The vulnerability is due to improper processing of malformed SIP messages. An
attacker could exploit this vulnerability by sending malformed SIP messages to
be processed by an affected device. An exploit could allow the attacker to
cause a memory leak and eventual reload of the affected device.
Cisco has released software updates that address this vulnerability. There are
no workarounds that address this vulnerability other than disabling SIP on the
This advisory is available at the following link:
This advisory is part of the March 23, 2016, release of the Cisco IOS and IOS
XE Software Security Advisory Bundled Publication, which includes six Cisco
Security Advisories that describe six vulnerabilities. All the vulnerabilities
have a Security Impact Rating of "High." For a complete list of advisories and
links to them, see Cisco Event Response: Semiannual Cisco IOS and IOS XE
Software Security Advisory Bundled Publication.
SIP is a popular signaling protocol that is used to manage voice and video
calls across IP networks such as the Internet. SIP handles all aspects of call
setup and termination. Voice and video are the most popular types of sessions
that SIP handles, but the protocol has the flexibility to accommodate other
applications that require call setup and termination. SIP call signaling can
use UDP port 5060, TCP port 5060, or Transport Layer Security (TLS) on TCP
port 5061 as the underlying transport protocol.
This vulnerability affects Cisco devices that are running a vulnerable release
of Cisco IOS, IOS XE, or Cisco Unified Communications Manager Software that is
configured to process SIP messages.
For information about which Cisco IOS and IOS XE Software releases are
vulnerable, see the "Fixed Software" section of this advisory. Recent releases
of Cisco IOS and IOS XE Software do not process SIP messages by default.
The following Cisco Unified Communications Manager software releases are
vulnerable. For information about the earliest Cisco Unified Communications
Software release that fixes the vulnerability described in this advisory, see
the "Fixed Software" section.
Cisco Unified Communications Manager 8.x
Cisco Unified Communications Manager 9.x
Cisco Unified Communications Manager 10.x
Cisco Unified Communications Manager 11.x
Note: Cisco Unified Communications Manager release 8.x reached the
End-of-Software-Maintenance milestone on July 26, 2015. Customers using Cisco
Unified Communications Manager 8.x releases should contact their Cisco support
team for assistance in upgrading to a supported release of Cisco Unified
Determining Whether SIP Is Running
Creating a dial peer by issuing the dial-peer configuration command will start
the SIP processes, causing the Cisco IOS device to process SIP messages. In
addition, several features in Cisco Unified Communications Manager Express,
such as ePhones, will also automatically start the SIP process when they are
configured, causing the device to start processing SIP messages. An example of
an affected Cisco IOS or IOS XE Software configuration follows:
dial-peer voice <Voice dial-peer tag> pots
In addition to inspecting the Cisco IOS device configuration for a dial-peer
command that causes the device to process SIP messages, administrators can
also use the show processes | include SIP command to determine whether Cisco
IOS Software is running the processes that handle SIP messages. In the
following example, the presence of the processes CCSIP_UDP_SOCKET or
CCSIP_TCP_SOCKET indicates that the Cisco IOS device will process SIP
Router#show processes | include SIP
149 Mwe 40F48254 4 1 400023108/24000 0 CCSIP_UDP_SOCKET
150 Mwe 40F48034 4 1 400023388/24000 0 CCSIP_TCP_SOCKET
Note: Because there are several ways that a device running Cisco IOS Software
can start processing SIP messages, administrators are advised not to rely on
the presence of specific configuration commands. Instead, it is recommended
that administrators use the show processes | include SIP command to determine
whether the device is processing SIP messages.
This vulnerability is triggered when a device that is running Cisco IOS, IOS
XE, or Cisco Unified Communications Manager Software processes malformed SIP
messages. Only traffic destined to the device can trigger the vulnerability;
transit SIP traffic is not an exploit vector. This vulnerability can be
exploited with SIP over IPv4 or IPv6.
Note: In cases where SIP is running over TCP transport, a TCP three-way
handshake is necessary to exploit this vulnerability.
Determining the Cisco IOS or IOS XE Software Release
To determine which Cisco IOS Software release is running on a Cisco product,
administrators can log in to the device, use the show version command in the
command-line interface, 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 image name appears 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 identifies a Cisco product that is running Cisco IOS
Software Release 15.5(2)T1 with an installed image name of
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 White Paper: Cisco IOS and NX-OS Software Reference
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this
Cisco has confirmed that this vulnerability does not affect Cisco IOS XR
Software or Cisco NX-OS Software.
Indicators of Compromise
To determine whether the vulnerability has been exploited on a device that is
running a vulnerable release of Cisco IOS or Cisco IOS XE Software, issue the
show memory debug leaks summary command from the command-line interface.
Note: There are no methods to determine whether the vulnerability has been
exploited on Cisco Unified Communications Manager Software.
The following example shows the output of a vulnerable Cisco IOS or IOS XE
device where there are observed memory leaks in CCSIP_UDP_SOCKET:
Router#show memory debug leaks summary
Adding blocks for GD...
Alloc PC Size Blocks Bytes What
Alloc PC Size Blocks Bytes What
0x30302064 0000001024 0000000001 0000001024 *Init*
0x31931D28 0000001376 0000000001 0000001376 Connection
0x330F1E38 0000001184 0000000001 0000001184 *In-use Packet Header*
0x34F298D4 0000000040 0000000220 0000008800 CCSIP_UDP_SOCKET
0x34F298D4 0000000080 0000000106 0000008480 CCSIP_UDP_SOCKET
0x34F298D4 0000000084 0000000055 0000004620 CCSIP_UDP_SOCKET
0x34F298D4 0000000088 0000000079 0000006952 CCSIP_UDP_SOCKET
0x34F298D4 0000000092 0000000073 0000006716 CCSIP_UDP_SOCKET
Note: The show memory debug leaks summary command may be CPU intensive and
should be used with caution.
There are no workarounds that address this vulnerability other than disabling
SIP on the vulnerable device.
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:
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 consult the Cisco
Security Advisories and Responses archive at http://www.cisco.com/go/psirt and
review subsequent advisories to determine exposure and a complete upgrade
In all cases, customers should ensure that the devices to upgrade 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 Technical Assistance Center (TAC):
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 menu 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
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
or IOS XE Software releasefor example, 15.1(4)M2 or 3.01.4Sin the following
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
Cisco Unified Communications Manager Software
Cisco UCM Software Major Release First Fixed Release
8.x Affected; migrate to 9.1(2)su4 or later
Exploitation and Public Announcements
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.
This vulnerability was found during the resolution of a support case.
Version Description Section Status Date
1.0 Initial public release. Final 2016-March-23
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.
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