A vulnerability in the PROFINET handler for Link Layer Discovery Protocol (LLDP) messages of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a crash on an affected device, resulting in a denial of service (DoS) condition.
The vulnerability is due to insufficient validation of LLDP messages in the PROFINET LLDP message handler. An attacker could exploit this vulnerability by sending a malicious LLDP message to an affected device. A successful exploit could allow the attacker to cause the affected device to reload.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
A companion advisory for affected devices that support PROFINET is available at the following link:
This advisory is part of the September 24, 2020, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 25 Cisco Security Advisories that describe 34 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: September 2020 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.
This vulnerability affects Cisco Industrial Ethernet devices if they are running a vulnerable release of Cisco IOS or IOS XE Software and have the PROFINET feature enabled. The PROFINET feature is enabled by default on platforms that support it.
The following Cisco products support PROFINET:
- Catalyst IE3200 Rugged Switches
- Catalyst IE3300 Rugged Switches
- Catalyst IE3400 Heavy Switches
- Catalyst IE3400 Rugged Switches
- Embedded Services 2020 Series Switches
- Embedded Services 3300 Series Switches
- Industrial Ethernet 2000 Series Switches
- Industrial Ethernet 2000U Series Switches
- Industrial Ethernet 3000 Series Switches
- Industrial Ethernet 4000 Series Switches
- Industrial Ethernet 4010 Series Switches
- Industrial Ethernet 5000 Series Switches
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine the Device Configuration
Option 1: show profinet status
To determine whether PROFINET is enabled on a device, use the show profinet status command and check the State that is reported in the output. If the command returns a state of Enabled, the PROFINET feature is enabled and the device is vulnerable. If the command returns a state of Disabled or if the command does not exist, the PROFINET feature is not enabled and the device is not affected by this vulnerability.
The following example shows the output of the show profinet status command on a device that has the PROFINET feature enabled:
Switch#show profinet status
State : Enabled
Option 2: show running-config all
Alternatively, use the show running-config all | include profinet command and look for an output line that contains only the word profinet. If the line is present, the PROFINET feature is enabled and the device is vulnerable. If profinet is not present alone on an output line, the PROFINET feature is not enabled and the device is not affected by this vulnerability.
The following example shows the output of the show running-config all | include profinet command on a device that has the PROFINET feature enabled:
Switch#show running-config all | include profinet
profinet vlan 1
no profinet id
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 Cisco IOS XR Software or Cisco NX-OS Software.
There are no workarounds that address this vulnerability.
However, customers who do not use the PROFINET feature can disable it by using the no profinet command in global configuration mode, as shown in the following example:
Enter configuration commands, one per line. End with CNTL/Z.
Switch#show profinet status
State : Disabled
Vlan : 1
Connected : No
ReductRatio : 128
Note: Disabling LLDP only is not a viable option because LLDP is required for proper PROFINET operation. Running PROFINET without LLDP is not supported, and PROFINET will force LLDP to start each time the device is reloaded, even if not configured specifically.
Cisco has released free software updates that address the vulnerability described in this advisory. 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:
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 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.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides the Cisco Software Checker to identify any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified (“Combined First Fixed”).
Customers can use the Cisco Software Checker to search advisories in the following ways:
- Choose the software and one or more releases
- Upload a .txt file that includes a list of specific releases
- Enter the output of the show version command
After initiating a search, customers can customize the search to include all Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication.
Customers can also use the following form to determine whether a release is affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE Software release—for example, 15.1(4)M2 or 3.13.8S:
By default, the Cisco Software Checker includes results only for vulnerabilities that have a Critical or High Security Impact Rating (SIR). To include results for Medium SIR vulnerabilities, customers can use the Cisco Software Checker on Cisco.com and check the Medium check box in the drop-down list under Impact Rating when customizing a search.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the Cisco IOS XE Software release.
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.
This vulnerability was found during the resolution of a Cisco TAC support case.
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.
Version Description Section Status Date 1.2 Removed Industrial Ethernet 1000 Series Switches from Vulnerable Products. Vulnerable Products Final 2020-DEC-09 1.1 Removed 2520 Connected Grid Switches and Industrial Ethernet 3010 Series Switches from affected products list as they don't support PROFINET. Vulnerable Products Final 2020-NOV-12 1.0 Initial public release. — Final 2020-SEP-24
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