CVE-2023-20097: Cisco Wireless LAN Controller RCE Flaw

CVE-2023-20097 Overview

A command injection vulnerability exists in Cisco Access Points (AP) software that allows an authenticated, local attacker to inject arbitrary commands and execute them with root privileges. This vulnerability stems from improper input validation of commands issued from a wireless controller to an AP. An attacker with Administrator access to the CLI of the controller can exploit this vulnerability by issuing a command with crafted arguments, potentially gaining full root access on the access point.

Critical Impact

Successful exploitation grants attackers full root access on affected Cisco Access Points, enabling complete device compromise and potential lateral movement within the wireless network infrastructure.

Affected Products

• Cisco Wireless LAN Controller Software
• Cisco Aironet Access Point Software (1540, 1560, 1800, 2800, 3800, 4800 series)
• Cisco Catalyst 9100 Series Access Points (9105, 9115, 9117, 9120, 9124, 9130)
• Cisco Catalyst IW6300 Heavy Duty Series Access Points
• Cisco IOS XE

Discovery Timeline

• March 23, 2023 - CVE-2023-20097 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-20097

Vulnerability Analysis

This vulnerability (CWE-77: Command Injection) resides in the command processing mechanism between Cisco Wireless LAN Controllers and managed Access Points. When commands are issued from the controller CLI to an AP, the software fails to properly sanitize user-supplied input before passing it to the underlying operating system shell. This allows an attacker with administrator-level CLI access to craft malicious arguments that break out of the intended command context and execute arbitrary commands with root privileges on the target access point.

The attack requires local access and high privileges (administrator credentials), which limits the exposure somewhat. However, the impact is significant as successful exploitation results in complete compromise of the confidentiality, integrity, and availability of the affected access point. An attacker who has already gained administrator access to a wireless controller could leverage this vulnerability to pivot deeper into the network infrastructure.

Root Cause

The root cause of CVE-2023-20097 is improper input validation in the command processing pipeline between Cisco wireless controllers and access points. The software fails to adequately sanitize special characters and command metacharacters in arguments passed through the CLI interface. This design flaw allows shell command injection when user-supplied input is incorporated into system commands without proper escaping or validation.

Attack Vector

The attack vector requires an attacker to first obtain administrator-level access to the CLI of a Cisco wireless controller. From this privileged position, the attacker can issue commands that are relayed to connected access points. By crafting command arguments containing shell metacharacters or command separators, the attacker can inject additional commands that execute with root privileges on the target AP.

The vulnerability exploits the trust relationship between the controller and its managed access points. Commands issued from the controller are processed with elevated privileges on the AP, and the lack of input validation allows this trust to be abused for command injection. This represents a classic privilege boundary violation where administrative access to one component (the controller) enables unauthorized root access to another (the access point).

Detection Methods for CVE-2023-20097

Indicators of Compromise

• Unusual CLI commands being issued from wireless controllers to access points, particularly those containing shell metacharacters (;, |, &, $(), backticks)
• Unexpected processes running with root privileges on access points
• Anomalous network traffic originating from access points that may indicate post-exploitation activity
• Authentication logs showing administrator-level access to wireless controller CLI from unexpected sources

Detection Strategies

• Enable comprehensive logging on Cisco wireless controllers to capture all CLI commands issued by administrators
• Monitor access point system logs for unexpected command execution or process spawning
• Implement network behavioral analysis to detect unusual traffic patterns from access points
• Review controller audit logs for commands containing suspicious special characters or unusual argument patterns

Monitoring Recommendations

• Configure syslog forwarding from all wireless controllers and access points to a centralized SIEM solution
• Set up alerts for administrator-level authentication events on wireless controller CLI interfaces
• Monitor for unauthorized configuration changes or firmware modifications on access points
• Implement baseline monitoring for normal AP behavior to detect anomalies indicating compromise

How to Mitigate CVE-2023-20097

Immediate Actions Required

• Review and update affected Cisco Wireless LAN Controller and Access Point software to the latest patched versions
• Audit administrator accounts on wireless controllers and enforce strong authentication with multi-factor authentication where possible
• Restrict CLI access to wireless controllers to only authorized personnel from trusted network segments
• Monitor for any signs of exploitation in controller and AP logs

Patch Information

Cisco has released security updates addressing this vulnerability. Organizations should consult the Cisco Security Advisory for detailed patching guidance specific to their deployed software versions. The advisory provides information on fixed software releases for Cisco IOS XE, Wireless LAN Controller Software, and Aironet Access Point Software.

Workarounds

• Implement strict access controls limiting CLI access to wireless controllers to a minimal set of trusted administrators
• Use network segmentation to isolate wireless management infrastructure from general user networks
• Consider implementing jump servers or privileged access management (PAM) solutions for controller CLI access
• Monitor and log all administrative sessions on wireless controllers for forensic purposes

# Recommended: Verify current software version on Cisco WLC
show version

# Review administrator access logs
show logging | include admin

# Check for any unauthorized configuration changes
show run-config commands