Summary
A vulnerability in the process that classifies traffic that is going to the Unified Threat Defense (UTD) component of Cisco IOS XE Software in controller mode could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
This vulnerability exists because UTD improperly handles certain packets as those packets egress an SD-WAN IPsec tunnel. An attacker could exploit this vulnerability by sending crafted traffic through an SD-WAN IPsec tunnel that is configured on an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Note: SD-WAN tunnels that are configured with Generic Routing Encapsulation (GRE) are not affected by this vulnerability.
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:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-utd-dos-hDATqxs
This advisory is part of the September 2024 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2024 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication
Affected Products
Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco IOS XE Software in controller mode, have UTD installed and enabled, and have SD-WAN tunnels configured to use IPsec:
- 1000 Series Integrated Services Routers (ISRs)
- Catalyst 8000v Edge Software
- Catalyst 8200 Series Edge Platforms
- Catalyst 8300 Series Edge Platforms
- Catalyst 8500L Edge Platforms
- Catalyst IR8300 Rugged Series Routers
Note: UTD is not installed on these devices by default. If the UTD file is not installed, the device is not vulnerable.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine Whether Cisco IOS XE Software is in Controller Mode
To determine whether the device is in controller mode or autonomous mode, use the show platform software device-mode command. If the output includes Device Operating-mode: Controller-Managed, the device is in controller mode, as shown in the following example:
Determine Whether UTD is Enabled
To determine whether UTD is enabled on a device, use the show utd engine standard status command. If the output shows a Yes under Running, UTD is enabled, as shown in the following example. If there is no output, the device is not affected. For more information, see the Install and Uninstall UTD Engine in SD-WAN with CLI guide.
Determine Whether an SD-WAN Tunnel is Configured to Use IPsec
To determine whether an SD-WAN tunnel is configured to use IPsec, use the show sdwan bfd sessions | include ipsec command. If there is output, the device has an SD-WAN tunnel configured with IPsec. If there is no output, the device is not affected. The following example shows the output on a device that has an SD-WAN tunnel configured with IPsec:
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:
- Catalyst SD-WAN Controller Software, formerly SD-WAN vSmart Controller Software
- Catalyst SD-WAN Manager Software, formerly SD-WAN vManage Software
- Catalyst SD-WAN Validator Software, formerly SD-WAN vBond Orchestrator Software
- Catalyst SD-WAN vEdge Cloud Routers
- Catalyst SD-WAN vEdge Series Routers
- IOS Software
- IOS XR Software
- Meraki products
- NX-OS Software
Workarounds
There are no workarounds that address this vulnerability. However, in environments where the UTD feature is not needed, customers can remove or disable the UTD feature to close the attack vector. For more information, see the Install and Uninstall UTD Engine in SD-WAN with CLI guide.
While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.
Fixed Software
Cisco has released free software updates that address the vulnerability described in this advisory. Customers with service contracts that entitle them to regular software updates should obtain security fixes through their usual update channels.
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.
The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool.
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. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”).
To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to determine whether a release is affected by any Cisco Security Advisory. To use the form, follow these steps:
- Choose which advisories the tool will search-only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
- Enter a release number-for example, 15.9(3)M2 or 17.3.3.
- Click Check.
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