Summary

• A vulnerability in the Central Web Authentication (CWA) feature of Cisco IOS XE Software for Wireless Controllers could allow an unauthenticated, adjacent attacker to bypass the pre-authentication access control list (ACL), which could allow access to network resources before user authentication.

  This vulnerability is due to a logic error when activating the pre-authentication ACL that is received from the authentication, authorization, and accounting (AAA) server. An attacker could exploit this vulnerability by connecting to a wireless network that is configured for CWA and sending traffic through an affected device that should be denied by the configured ACL before user authentication. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device before the user authentication is completed, allowing the attacker to access trusted networks that the device might be protecting.

  Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-c9800-cwa-acl-nPSbHSnA

  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

  At the time of publication, this vulnerability affected the following Cisco products if they were running a vulnerable release of Cisco IOS XE Software and had CWA enabled:

  • Catalyst 9800-CL Wireless Controllers for Cloud
  • Catalyst 9800 Embedded Wireless Controllers for Catalyst 9300, 9400, and 9500 Series Switches
  • Catalyst 9800 Series Wireless Controllers
  • Embedded Wireless Controllers on Catalyst Access Points

  For information about which Cisco software releases are vulnerable, see the Fixed Software 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:

  • IOS Software
  • IOS XR Software
  • Meraki products
  • NX-OS Software
  • Wireless LAN Controller (WLC) AireOS Software

Details

• Exploitation of this vulnerability could allow an attacker to bypass protections that are provided by an ACL that is applied on an affected device. The overall impact of exploitation is organization specific because it depends on the importance of the assets that the ACL was supposed to protect. Customers should evaluate how exploitation of this vulnerability would impact their network and proceed according to their own vulnerability-handling and remediation processes.

Workarounds

• There is a workaround that addresses this vulnerability: Add an IPv4 ACL or IPv6 ACL, as necessary.

  Add an IPv6 ACL

  If the redirection ACL that is configured on the wireless controller is an IPv4 ACL, then a new IPv6 ACL that denies all traffic must be created and applied during the CWA authentication phase. To do so, complete the following steps:

  First, on the wireless controller, do the following:

  1. Connect to the web management interface.
  2. Choose Configuration > Security > ACL.
  3. Add a new IPv6 extended ACL that denies all traffic.

  Then, in Identity Services Engine (ISE), do the following:

  1. Connect to the web management interface.
  2. Choose Policy > Policy Elements > Results > Authorization > Authorization Profiles.
  3. Choose the authorization profile that is used for CWA.
  4. Check Airespace IPv6 ACL Name under Common Tasks with the ACL name that was configured in the previous step.

  Add an IPv4 ACL

  If the redirection ACL that is configured on the wireless controller is an IPv6 ACL, then a new IPv4 ACL that denies all traffic must be created and applied during the CWA authentication phase. To do so, complete the following steps:

  First, on the wireless controller, do the following:

  1. Connect to the web management interface.
  2. Choose Configuration > Security > ACL.
  3. Add a new IPv4 extended ACL that denies all traffic.

  Then, in ISE, do the following:

  1. Connect to the web management interface.
  2. Choose Policy > Policy Elements > Results > Authorization > Authorization Profiles.
  3. Choose the authorization profile that is used for CWA.
  4. Check Airespace ACL Name under Common Tasks with the ACL name that was configured in the previous step.

  While this workaround 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

• 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.

  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:

  1. Choose which advisories the tool will search—only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
  2. Enter a release number—for example, 15.9(3)M2 or 17.3.3.
  3. Click Check.

   

  Only this advisory All Critical and High advisories All advisories

   

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

• This vulnerability was found during the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-c9800-cwa-acl-nPSbHSnA

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2024-SEP-25

  Show Less

---