Cisco IOS XE Software for Catalyst 9800 Series Wireless Controller for Cloud Unauthenticated Access to Certificate Enrollment Service Vulnerability

TL;DR 📌

A medium-severity vulnerability has been identified in the Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers for Cloud. This flaw allows unauthenticated remote attackers to access the public-key infrastructure (PKI) server, potentially enabling unauthorized device enrollment. Workarounds are available, and Cisco has recommended software updates to fully mitigate the risk.

What happened 🕵️‍♂️

A vulnerability in the Day One setup process of Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers for Cloud could allow an unauthenticated, remote attacker to access the PKI server running on affected devices. This issue arises due to incomplete cleanup after the Day One setup process. An attacker could exploit this vulnerability by sending Simple Certificate Enrollment Protocol (SCEP) requests, potentially allowing them to request a certificate and join an attacker-controlled device to the virtual wireless controller.

Affected products 🖥️

The vulnerability affects Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers for Cloud, regardless of device configuration. Cisco has confirmed that this vulnerability does not affect Cisco IOS XE Software for Catalyst 9800 Series Wireless Hardware-based Controllers.

Fixed software 🔧

Upgrade to the first fixed release in your train (or later):

Workarounds 🧯

Administrators can mitigate the vulnerability by shutting down the PKI server that matches the hostname of the wireless LAN controller (WLC). The following commands can be used:

vewlc# conf t
vewlc(config)# crypto pki server vewlc_WLC_CA
vewlc(cs-server)# shutdown
vewlc(cs-server)# exit
vewlc# write memory

While this workaround has been tested successfully, customers should evaluate its applicability and potential impact on their specific environments before implementation.

Risk in context 🎯

The highest CVSS score for this vulnerability is 5.3, categorizing it as Medium severity. The risk is primarily due to the potential for unauthorized access and device enrollment, which could lead to further exploitation within the network. While there is no immediate public exploitation reported, the vulnerability’s nature poses a significant risk if left unaddressed.

Fast facts ⚡

• Vulnerability: Unauthenticated access to PKI server
• CVSS Score: 5.3 (Medium)
• Exploitation Potential: Requires no authentication
• Workarounds Available: Yes
• Public Exploitation: None reported

For leadership 🧭

This vulnerability presents a Medium risk to your organization, with a CVSS score of 5.3. It allows unauthenticated remote access to the PKI server, which could lead to unauthorized device enrollment and potential lateral movement within your network.

Remediation ask: Please ensure that the workaround is implemented immediately and plan to apply any available software updates as soon as they are released.

Operational impact: Implementing the workaround requires a brief maintenance window, with no expected configuration drift.

Now / Next / Later:

• Now: Implement the provided workaround to mitigate immediate risk.
• Next: Monitor for updates from Cisco regarding fixed software releases.
• Later: Schedule a review of network security policies to address potential vulnerabilities and ensure compliance.