CVE-2022-20695: Cisco WLAN Controller Auth Bypass Flaw

CVE-2022-20695 Overview

A critical authentication bypass vulnerability exists in Cisco Wireless LAN Controller (WLC) Software that could allow an unauthenticated, remote attacker to bypass authentication controls and log in to the device through the management interface. This vulnerability stems from improper implementation of the password validation algorithm, enabling attackers to authenticate using specially crafted credentials.

Critical Impact

An unauthenticated remote attacker can bypass authentication and gain administrative access to affected Cisco Wireless LAN Controllers, potentially compromising the entire wireless network infrastructure.

Affected Products

• Cisco Wireless LAN Controller Software versions 8.10.151.0 and 8.10.162.0
• Cisco 3504, 5520, and 8540 Wireless Controllers
• Cisco Virtual Wireless Controller
• Cisco Aironet 1540, 1560, 1815, 1830, 1850, 2800, 3800, and 4800 Series Access Points (when managed by affected WLC software)

Discovery Timeline

• April 15, 2022 - CVE-2022-20695 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-20695

Vulnerability Analysis

This authentication bypass vulnerability (CWE-303: Incorrect Implementation of Authentication Algorithm, CWE-287: Improper Authentication) affects the management interface of Cisco Wireless LAN Controllers. The flaw resides in how the WLC Software validates passwords during the authentication process. Due to a logic error in the password validation algorithm, an attacker can craft specific credentials that the system incorrectly accepts as valid.

When successfully exploited, the attacker can obtain administrative privileges on the affected device, giving them full control over the wireless network infrastructure. This includes the ability to modify configurations, intercept traffic, add rogue access points, and potentially pivot to other network segments.

It is important to note that this vulnerability requires a non-default device configuration to be exploitable. Organizations should review the Cisco Security Advisory to determine if their specific configuration is vulnerable.

Root Cause

The root cause of CVE-2022-20695 is an incorrect implementation of the password validation algorithm within the Cisco WLC Software authentication functionality. The flawed logic fails to properly verify credentials under certain conditions, allowing crafted input to satisfy authentication requirements without providing valid credentials. This represents a fundamental failure in the authentication subsystem's design.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no prior authentication or user interaction. An attacker with network access to the WLC management interface can exploit this vulnerability by submitting specially crafted credentials through the authentication mechanism.

The attack flow proceeds as follows:

1. The attacker identifies an exposed Cisco WLC management interface
2. The attacker crafts malicious credentials designed to exploit the flawed password validation logic
3. These crafted credentials are submitted to the authentication endpoint
4. The vulnerable validation algorithm incorrectly accepts the crafted credentials
5. The attacker gains administrative access to the WLC

The specific technical details of the crafted credentials are documented in the Cisco Security Advisory.

Detection Methods for CVE-2022-20695

Indicators of Compromise

• Unexpected administrative logins to WLC management interfaces from unfamiliar IP addresses
• Authentication logs showing successful logins without corresponding valid credential entries
• Configuration changes made by administrative accounts during unusual hours or from unexpected sources
• Newly created administrative accounts or modifications to existing account permissions

Detection Strategies

• Monitor WLC authentication logs for anomalous login patterns and failed/successful authentication sequences
• Implement network monitoring to detect connections to WLC management interfaces from unauthorized networks
• Deploy intrusion detection systems with signatures for known WLC exploitation attempts
• Conduct regular audits of administrative access and configuration changes on wireless controllers

Monitoring Recommendations

• Enable comprehensive logging on all Cisco WLC devices and forward logs to a centralized SIEM
• Configure alerts for any administrative access from non-whitelisted IP addresses or network segments
• Implement real-time monitoring of WLC configuration changes with automated notifications
• Establish baseline authentication patterns and alert on deviations from normal behavior

How to Mitigate CVE-2022-20695

Immediate Actions Required

• Review the Cisco Security Advisory to determine if your configuration is vulnerable
• Restrict network access to WLC management interfaces using access control lists (ACLs)
• Implement network segmentation to isolate WLC management from untrusted networks
• Enable multi-factor authentication where supported for management access
• Monitor for and investigate any suspicious authentication activity

Patch Information

Cisco has released software updates that address this vulnerability. Affected organizations should consult the Cisco Security Advisory for specific fixed software versions and upgrade instructions. Given the critical nature of this vulnerability and its potential impact on network infrastructure security, patching should be prioritized as an urgent remediation activity.

Workarounds

• Implement strict ACLs to limit management interface access to trusted administrative networks only
• Disable remote management access if not operationally required and use local console access instead
• Deploy a jump server or bastion host for administrative access, adding an additional authentication layer
• Consider implementing VPN requirements for any remote management access to WLC devices

# Example ACL configuration to restrict WLC management access
# Apply to management interface to limit access to trusted admin subnet
config acl create Management-ACL
config acl rule add Management-ACL 1 permit 10.10.10.0 255.255.255.0 any
config acl rule add Management-ACL 2 deny 0.0.0.0 0.0.0.0 any
config acl apply Management-ACL