Cisco Security Advisory-
With new installations of Cisco Wireless LAN Controller Software, the installation scripts create default communities for Simple Network Management Protocol (SNMP) Version 2 (SNMPv2) and a default username for SNMP Version 3 (SNMPv3), both allowing for read and write access.
As documented in the Cisco Wireless LAN Controller Configuration Best Practices guide, the SNMP configuration should either be changed or disabled depending on the environmental requirements. If the default communities and username are not changed or disabled, the system is open for read and write access through SNMP.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-wlc
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The following workarounds are available:
- Administrators should delete the default SNMPv3 user.
- Administrators should delete the default public and private community strings.
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Cisco has not released software updates to address the issue described in this advisory.
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Cisco Wireless LAN Controller Best Practice: Change SNMPv3 Default User
Check the SNMPv3 default user. By default, the controller is configured with a username that should be disabled or changed.
The following example shows how to verify the SNMPv3 users configuration:
(Cisco Controller) >show snmpv3user
SNMP v3 User Name AccessMode Authentication Encryption
-------------------- ----------- -------------- ----------
default Read/Write HMAC-SHA CFB-AES
The following examples shows how to delete the default SNMPv3 user and create a new user:
(Cisco Controller) >config snmp v3user delete default
(Cisco Controller) >config snmp v3user create nondefault rw hmacsha des authkey
<encrypkey12characters>Cisco Wireless LAN Controller Best Practice: Delete SNMPv2 Default Communities
Check the SNMPv2 default communities. By default, the controller is configured with default community strings that should be removed.
The following example shows how to verify the SNMPv2 community settings:
> show snmpcommunity SNMP Community Name Client IP Address Client IP Mask Access Mode Status ---------------- ----------- -------------- ---------- public 0.0.0.0 0.0.0.0 Read Only Enable ********** 0.0.0.0 0.0.0.0 Read/Write Enable
The following example shows how to delete an active SNMP Community:
> config> snmp community delete private
> show snmpcommunity
SNMP Community Name Client IP Address Client IP Mask Access Mode Status ---------------- ----------- -------------- ---------- public 0.0.0.0 0.0.0.0 Read Only EnableThe following example shows how to configure an SNMP Community:
> config> snmp community create SNMP_Community
>show snmpcommunity
SNMP Community Name Client IP Address Client IP Mask Access Mode Status ---------------- ----------- -------------- ---------- SNMP_Community 0.0.0.0 0.0.0.0 Read Only EnableNote: Ensure that the SNMP settings match between the controller and the Wireless Control
System (WCS)/Network Control System(NCS)/Prime Infrastructure (PI). In addition, use encryption and hash keys that match the security policies.The Cisco Wireless LAN Controller Configuration Best Practices guide is available at the following URL: https://www.cisco.com/c/en/us/td/docs/wireless/technology/wlc/8-5/82463-wlc-config-best-practice.html#pgfId-379998
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the issue that is described in this advisory.
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Cisco would like to thank Jim Thomas, Senior Security Architect with Insight, for reporting this issue.
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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.
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Show LessVersion Description Section Status Date 1.1 Updated the "Recommendations" section, including the example output for the 'show snmpcommunity' command. Configuration examples that create, delete, and verify SNMP communities were added. The 'Summary' section was updated to include information about 'default usernames' and 'default communities.' Summary, Recommendations Final 2018-April-23 1.0 Initial public release. — Final 2018-April-18
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