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
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 Communications Manager.
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 messages:
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
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.
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 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 White Paper: Cisco IOS and NX-OS Software Reference Guide.
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.