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AUSCERT External Security Bulletin Redistribution
ESB-2018.3501.2
Cisco Small Business Switches Privileged Access Vulnerability
17 January 2019
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Small Business Switches
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Unauthorised Access -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2018-15439
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-sbsw-privacc
Revision History: January 17 2019: Updated the products confirmed not vulnerable section
November 8 2018: Initial Release
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco Small Business Switches Privileged Access Vulnerability
Priority: Critical
Advisory ID: cisco-sa-20181107-sbsw-privacc
First Published: 2018 November 7 16:00 GMT
Last Updated: 2019 January 16 22:24 GMT
Version 1.2: Interim
Workarounds: Yes
Cisco Bug IDs: CSCvk20713 CSCvm11846
Summary
o A vulnerability in the Cisco Small Business Switches software could allow
an unauthenticated, remote attacker to bypass the user authentication
mechanism of an affected device.
The vulnerability exists because under specific circumstances, the affected
software enables a privileged user account without notifying administrators
of the system. An attacker could exploit this vulnerability by using this
account to log in to an affected device and execute commands with full
admin rights.
Cisco has not released software updates that address this vulnerability.
This advisory will be updated with fixed software information once fixed
software becomes available. There is a workaround to address this
vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-20181107-sbsw-privacc
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco Small Business product
families running any software release if no user accounts with access
privilege set to level 15 are configured on the device:
? Cisco Small Business 200 Series Smart Switches
? Cisco Small Business 300 Series Managed Switches
? Cisco Small Business 500 Series Stackable Managed Switches
? Cisco 250 Series Smart Switches
? Cisco 350 Series Managed Switches
? Cisco 350X Series Stackable Managed Switches
? Cisco 550X Series Stackable Managed Switches
Determining the Cisco Small Business Switches Software Release
To determine which Cisco Small Business Switches Software release is
running on a device, use the show version command from the CLI prompt. The
following example shows the output of the command for a device that is
running software version 1.4.9.4:
Switch# show version
SW version 1.4.9.04 (date 20-Jul-2018 time 17:14:12)
Determining If Privilege Level 15 User Accounts Are Present on the Device
Configuration
To determine if any privilege level 15 user accounts are present in the
device configuration, use the command show running-config | include
privilege 15 from a CLI prompt. An empty output would indicate that no user
accounts with level 15 access privilege are configured on the device; the
device is vulnerable if also running an affected software release.
The following example shows the output of the command show running-config |
include privilege 15 when a user account with access privilege set to level
15 is not present on the running configuration.
Switch# show running-config | include privilege 15
Switch#
The following example shows the output of the command show running-config |
include privilege 15 when a user account with access privilege set to level
15 is present on the running configuration. This device is not vulnerable:
Switch# show running-config | include privilege 15
username <user-ID> password encrypted <encrypted-password> privilege 15
Note: Some hardware/software combinations may not support the piping ("|")
of commands. In that case, use the command show running-config with no
pipes and scan the output for the relevant configuration lines.
Additional information is available in the Details section of this
advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
? Cisco 200E Series Smart Switches
? Cisco 220 Series Smart Switches
Cisco has also confirmed that this vulnerability does not affect devices
running Cisco IOS Software, Cisco IOS XE Software, or Cisco NX-OS Software.
Details
o Cisco Small Business Switches are typically deployed within small office/
home office (SOHO) network environments. The default configuration on the
devices listed as vulnerable includes a default, privileged user account
that is used for the initial login and cannot be removed from the system.
An administrator may disable this account by configuring other user
accounts with access privilege set to level 15. However, if all
user-configured privilege level 15 accounts are removed from the device
configuration, an affected software release re-enables the default
privileged user account without notifying administrators of the system.
Under these circumstances, an attacker can use this account to log in to an
affected device and execute commands with full admin rights.
Note: The default user account is defined in a software-internal data
structure and is not visible in either the running configuration or the
startup configuration of an affected device.
Workarounds
o The workaround consists of adding at least one user account with access
privilege set to level 15 in the device configuration. The following
example shows how to configure an account by using admin as user ID,
setting the access privilege to level 15, and defining the password by
replacing <strong_password> with a complex password chosen by the user. By
adding this user account, the default privileged account will be disabled.
Switch# configure terminal
Switch(config)# username admin privilege 15 password <strong_password>
The command show running-config | include privilege 15 will now produce the
following output:
Switch# show running-config | include privilege 15
username admin password encrypted <encrypted-password> privilege 15
Fixed Software
o Cisco has not released software updates that address this vulnerability.
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:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.html
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 regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts page, to determine exposure and a
complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
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 TAC:
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html
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.
Fixed Releases
Cisco has not released software updates that address the vulnerability
described in this advisory.
Exploitation and Public Announcements
o 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.
Source
o Cisco would like to thank Thor Simon of Two Sigma Investments LP for
reporting this vulnerability.
Cisco Security Vulnerability Policy
o 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.
Subscribe to Cisco Security Notifications
o Subscribe
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-20181107-sbsw-privacc
Revision History
o
+---------+-------------------------+------------+---------+------------------+
| Version | Description | Section | Status | Date |
+---------+-------------------------+------------+---------+------------------+
| | Updated the Products | Vulnerable | | |
| 1.2 | Confirmed Not | Products | Interim | 2019-January-16 |
| | Vulnerable section | | | |
+---------+-------------------------+------------+---------+------------------+
| | Added note about pipes | | | |
| | to "Determining If | | | |
| 1.1 | Privilege Level 15 User | Vulnerable | Interim | 2018-November-12 |
| | Accounts Are Present on | Products | | |
| | the Device | | | |
| | Configuration" | | | |
+---------+-------------------------+------------+---------+------------------+
| 1.0 | Initial public release. | -- | Interim | 2018-November-07 |
+---------+-------------------------+------------+---------+------------------+
- --------------------------------------------------------------------------------
Cisco Small Business Switches Privileged Access Vulnerability
Priority: Critical
Advisory ID: cisco-sa-20181107-sbsw-privacc
First Published: 2018 November 7 16:00 GMT
Version 1.0: Interim
Workarounds: Yes
Cisco Bug IDs: CSCvk20713 CSCvm11846
CVE-2018-15439
CVSS Score:
Base 9.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Summary
* A vulnerability in the Cisco Small Business Switches software could allow
an unauthenticated, remote attacker to bypass the user authentication
mechanism of an affected device.
The vulnerability exists because under specific circumstances, the affected
software enables a privileged user account without notifying administrators
of the system. An attacker could exploit this vulnerability by using this
account to log in to an affected device and execute commands with full
admin rights.
Cisco has not released software updates that address this vulnerability.
This advisory will be updated with fixed software information once fixed
software becomes available. There is a workaround to address this
vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181107-sbsw-privacc
Affected Products
* Vulnerable Products
This vulnerability affects the following Cisco Small Business product
families running any software release if no user accounts with access
privilege set to level 15 are configured on the device:
+ Cisco Small Business 200 Series Smart Switches
+ Cisco Small Business 300 Series Managed Switches
+ Cisco Small Business 500 Series Stackable Managed Switches
+ Cisco 250 Series Smart Switches
+ Cisco 350 Series Managed Switches
+ Cisco 350X Series Stackable Managed Switches
+ Cisco 550X Series Stackable Managed Switches
Determining the Cisco Small Business Switches Software Release
To determine which Cisco Small Business Switches Software release is
running on a device, use the show version command from the CLI prompt. The
following example shows the output of the command for a device that is
running software version 1.4.9.4:
Switch# show version
SW version 1.4.9.04 (date 20-Jul-2018 time 17:14:12)
Determining if Privilege Level 15 User Accounts Are Present on the Device
Configuration
To determine if any privilege level 15 user accounts are present in the
device configuration, use the command show running-config | include
privilege 15 from a CLI prompt. An empty output would indicate that no user
accounts with level 15 access privilege are configured on the device; the
device is vulnerable if also running an affected software release.
The following example shows the output of the command show running-config |
include privilege 15 when a user account with access privilege set to level
15 is not present on the running configuration.
Switch# show running-config | include privilege 15
Switch#
The following example shows the output of the command show running-config |
include privilege 15 when a user account with access privilege set to level
15 is present on the running configuration. This device is not vulnerable:
Switch# show running-config | include privilege 15
username <user-ID> password encrypted <encrypted-password> privilege 15
Additional information is available in the Details section of this
advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
+ Cisco 220 Series Smart Switches
Cisco has also confirmed that this vulnerability does not affect devices
running Cisco IOS Software, Cisco IOS XE Software, or Cisco NX-OS Software.
Details
* Cisco Small Business Switches are typically deployed within small office/
home office (SOHO) network environments. The default configuration on the
devices listed as vulnerable includes a default, privileged user account
that is used for the initial login and cannot be removed from the system.
An administrator may disable this account by configuring other user
accounts with access privilege set to level 15. However, if all
user-configured privilege level 15 accounts are removed from the device
configuration, an affected software release re-enables the default
privileged user account without notifying administrators of the system.
Under these circumstances, an attacker can use this account to log in to an
affected device and execute commands with full admin rights.
Note: The default user account is defined in a software-internal data
structure and is not visible in either the running configuration or the
startup configuration of an affected device.
Workarounds
* The workaround consists of adding at least one user account with access
privilege set to level 15 in the device configuration. The following
example shows how to configure an account by using admin as user ID,
setting the access privilege to level 15, and defining the password by
replacing <strong_password> with a complex password chosen by the user. By
adding this user account, the default privileged account will be disabled.
Switch# configure terminal
Switch(config)# username admin privilege 15 password <strong_password>
The command show running-config | include privilege 15 will now produce the
following output:
Switch# show running-config | include privilege 15
username admin password encrypted <encrypted-password> privilege 15
Fixed Software
* Cisco has not released software updates that address this vulnerability.
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:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.html
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 regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts page, to determine exposure and a
complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
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 TAC:
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html
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.
Fixed Releases
Cisco has not released software updates that address the vulnerability
described in this advisory.
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.
Source
* Cisco would like to thank Thor Simon of Two Sigma Investments LP for
reporting this vulnerability.
URL
* https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-20181107-sbsw-privacc
Revision History
*
+----------------------------------------------------------------------------+
| Version | Description | Section | Status | Date |
|---------+--------------------------+---------+---------+-------------------|
| 1.0 | Initial public release. | - | Interim | 2018-November-07 |
+----------------------------------------------------------------------------+
- --------------------------END INCLUDED TEXT--------------------
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