CVE-2023-20243 : Security Advisory and Response

This CVE-2023-20243 concerns a vulnerability in the RADIUS message processing feature of Cisco Identity Services Engine (ISE) that could potentially allow an unauthenticated, remote attacker to disrupt the processing of RADIUS packets on the affected system.

Understanding CVE-2023-20243

In this section, we will delve deeper into the nature of the CVE-2023-20243 vulnerability, its impact, technical details, affected systems, and mitigation strategies.

What is CVE-2023-20243?

Cisco Identity Services Engine (ISE) is affected by a vulnerability in its RADIUS message processing feature, leading to a scenario where an attacker can disrupt the authentication and authorization processes by exploiting improper handling of RADIUS accounting requests. The attack could result in network access device (NAD) failures and denial of service for legitimate users.

The Impact of CVE-2023-20243

The exploitation of this vulnerability could lead to the abrupt restart of the RADIUS process within Cisco ISE, causing authentication and authorization delays, and ultimately denying network access to legitimate users. However, clients who are already authenticated to the network would remain unaffected by this disruption.

Technical Details of CVE-2023-20243

The technical details of CVE-2023-20243 include the vulnerability description, affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

The vulnerability arises from the improper handling of certain RADIUS accounting requests within the Cisco ISE RADIUS message processing feature. Attackers can exploit this flaw by sending crafted authentication requests to network access devices using Cisco ISE for AAA functions, leading to service disruptions.

Affected Systems and Versions

Multiple versions of the Cisco Identity Services Engine Software, including 3.1.0, 3.2.0, and their respective patches, are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by sending malicious RADIUS accounting requests, either to NADs using Cisco ISE or directly to Cisco ISE if the RADIUS shared secret is known. Successful exploitation can result in service interruptions and denial of network access to legitimate users.

Mitigation and Prevention

To address CVE-2023-20243, immediate steps must be taken by organizations using Cisco ISE to prevent potential exploits and secure their systems against disruptions.

Immediate Steps to Take

Organizations should consider manually restarting affected Policy Service Nodes (PSNs) to restore the processing of RADIUS packets and mitigate the impact of the vulnerability.

Long-Term Security Practices

Implementing robust network security measures, regularly monitoring for abnormal RADIUS packet processing, and maintaining secure authentication practices can help prevent similar vulnerabilities from being exploited in the future.

Patching and Updates

Cisco may release patches or updates to address the vulnerability in the RADIUS message processing feature of Cisco Identity Services Engine. Organizations are advised to apply relevant patches promptly to safeguard their systems against potential attacks.