Cisco IOS, IOS XE, and IOS XR Software Link Layer Discovery Protocol Buffer Overflow Vulnerabilities

These vulnerabilities affect Cisco devices that are running a vulnerable release of Cisco IOS Software, Cisco IOS XE Software, or Cisco IOS XR Software and are configured to use LLDP. The default state of the LLDP feature is platform- and release-dependent.

For information about which Cisco IOS, IOS XE, and IOS XR Software releases are vulnerable, see the Fixed Software section of this advisory.

Assessing the LLDP Configuration

To determine whether a device is configured to use LLDP, administrators can log in to the device and use the show lldp command in the CLI. If the device is configured to use LLDP, the output of the command will be similar to the following:

Router> show lldp

Global LLDP Information:
   Status: ACTIVE
   LLDP advertisements are sent every 30 seconds
   LLDP hold time advertised is 120 seconds
   LLDP interface reinitialisation delay is 2 seconds

If use of LLDP is configured for only specific interfaces of a device, administrators can instead use the show lldp interface command in the CLI to determine which interfaces are configured to use LLDP.

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
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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
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For information about the naming and numbering conventions for Cisco IOS XE Software releases, see the Cisco IOS and NX-OS Software Reference Guide.

Determining the Cisco IOS XR Software Release

To determine which Cisco IOS XR 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 XR Software, the system banner displays Cisco IOS XR Software or similar text. In addition, the System image file is field displays the location and name of the system image file that is running on the device, followed by the name of the hardware product.

The following example shows the output of the show version command for a device that is running Cisco IOS XR Software Release 5.3.4:

RP/0/RSP0/CPU0:ASR9001# show version
Wed Jan 24 01:32:32.751 EST

Cisco IOS XR Software, Version 5.3.4[Default]
Copyright (c) 2017 by Cisco Systems, Inc.

ROM: System Bootstrap, Version 2.04(20140227:092320) [ASR9K ROMMON],  

ASR9001 uptime is 6 hours, 17 minutes
System image file is "bootflash:disk0/asr9k-os-mbi-5.3.4.sp4-1.0.0/0x100000/mbiasr9k-rp.vm"

cisco ASR9K Series (P4040) processor with 8388608K bytes of memory.
P4040 processor at 1500MHz, Revision 2.0
ASR-9001 Chassis
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No other Cisco products are currently known to be affected by these vulnerabilities.

Cisco has confirmed that these vulnerabilities do not affect Cisco NX-OS Software.

from Cisco Security Advisory https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-lldp