A vulnerability in the boot logic of Cisco Access Points Software could allow an authenticated, local attacker to execute unsigned code at boot time. The vulnerability is due to an improper check that is performed by the area of code that manages system startup processes. An attacker could exploit this vulnerability by modifying a specific file that is stored on the system, which would allow the attacker to bypass existing protections. A successful exploit could allow the attacker to execute unsigned code at boot time and bypass the software image verification check part of the secure boot process of an affected device. Note: To exploit this vulnerability, the attacker would need to have access to the development shell (devshell) on the device. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ap-privesc-wEVfp8Ud
A vulnerability in the boot logic of Cisco Access Points Software could allow an authenticated, local attacker to execute unsigned code at boot time.
The vulnerability is due to an improper check that is performed by the area of code that manages system startup processes. An attacker could exploit this vulnerability by modifying a specific file that is stored on the system, which would allow the attacker to bypass existing protections. A successful exploit could allow the attacker to execute unsigned code at boot time and bypass the software image verification check part of the secure boot process of an affected device.
Note: To exploit this vulnerability, the attacker would need to have access to the development shell (devshell) on the device.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ap-privesc-wEVfp8Ud
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco Access Point Software:
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
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 any Cisco Access Point series that is not listed in the Vulnerable Products section of this advisory.
APs that are running the Cisco AP-COS operating system contain a debugging and troubleshooting mechanism known as devshell. This feature was designed to allow secure, controlled access to the underlying Linux operating system and debugging information.
The devshell feature can provide information that is not accessible through existing show or debug commands. Cisco development engineers can request low-level information through this feature without having to update the software that is running on a device. This can provide several advantages, such as allowing data to be collected without a reboot, which can lead to the loss of important values that indicate error state issues and a delay in problem resolution.
Access to the devshell feature must be explicitly authorized by the customer; Cisco personnel cannot access this feature without customer consent.
There are no workarounds that address this vulnerability.
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:
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 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 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.
The process to upgrade the APs requires administrators to upgrade the wireless controller that the APs are registered to.
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s). To ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
Cisco Access Points Managed by Wireless LAN Controller or Mobility Express
| Cisco Wireless LAN Controller Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in This Collection of Advisories |
|---|---|---|
| 8.5 and earlier | 8.5.171.0 | 8.5.171.0 |
| 8.6 - 8.9 | Migrate to a fixed release. | 8.10.151.0 |
| 8.10 | 8.10.150.0 | 8.10.151.0 |
Cisco Access Points Managed by Catalyst 9800 Wireless Controller or Embedded Wireless Controller on Catalyst Access Points (EWC)
| Cisco Catalyst 9800 Wireless Controller Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in This Collection of Advisories |
|---|---|---|
| 16.12 and earlier | 16.12.5 | 16.12.5 |
| 17.1 | Migrate to a fixed release. | 17.3.3 |
| 17.2 | Migrate to a fixed release. | 17.3.3 |
| 17.3 | 17.3.3 | 17.3.3 |
| 17.4 | Migrate to a fixed release. | 17.5.1 (Mar 2021) |
| 17.5 and later | Not vulnerable. | Not vulnerable. |
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 internal security testing.
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 |
|---|---|---|---|---|
| 1.0 | Initial public release. | - | Final | 2021-MAR-24 |
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