Cisco IOS and IOS XE Software Smart Install Denial of Service Vulnerability

This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS or IOS XE Software and have the Smart Install client feature enabled.

Only Smart Install client switches are affected by the vulnerability that is described in this advisory. Cisco devices that are configured as a Smart Install director are not affected by this vulnerability.

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

Notes Regarding Specific Releases

Smart Install client functionality is enabled by default on Cisco IOS Software switches on software releases that have not been updated to address Cisco bug ID CSCvd36820.

Switches that are running releases earlier than Cisco IOS Software Release 12.2(52)SE are not capable of running Smart Install, but they can be Smart Install clients if they support the archive download-sw privileged EXEC command.

Determining Whether the Smart Install Client Feature Is Enabled

To determine whether a device is configured with the Smart Install client feature enabled, use the show vstack config privileged EXEC command on the Smart Install client. An output of Role: Client and Oper Mode: Enabled or Role: Client (SmartInstall enabled) from the show vstack config command confirms that the feature is enabled on the device.

The following examples show the output of the show vstack config command on Cisco Catalyst Switches that are configured as Smart Install clients:

switch1# show vstack config
 Role: Client (SmartInstall enabled)
 .
 .
 .

switch2# show vstack config
 Capability: Client
 Oper Mode: Enabled
 Role: Client
 .
 .
 .

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.

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.

from Cisco Security Advisory https://ift.tt/2pKE2Vu