CVE-2024-20414: Cisco IOS XE Web UI CSRF Vulnerability

CVE-2024-20414 Overview

A cross-site request forgery (CSRF) vulnerability exists in the web UI feature of Cisco IOS Software and Cisco IOS XE Software that could allow an unauthenticated, remote attacker to conduct CSRF attacks on affected systems. This vulnerability stems from the web UI incorrectly accepting configuration changes through the HTTP GET method, enabling attackers to manipulate device configurations by tricking authenticated administrators into clicking malicious links.

Critical Impact

Successful exploitation allows attackers to change the configuration of affected Cisco networking devices without authorization, potentially compromising network infrastructure security and enabling further attacks.

Affected Products

• Cisco IOS XE Software (versions 3.2.x through 17.13.x)
• Cisco IOS Software (versions 15.2(6)E through 15.2(8)E)
• Cisco networking devices with web UI enabled

Discovery Timeline

• September 25, 2024 - CVE-2024-20414 published to NVD
• October 2, 2024 - Last updated in NVD database

Technical Details for CVE-2024-20414

Vulnerability Analysis

This CSRF vulnerability enables unauthenticated remote attackers to execute unauthorized configuration changes on Cisco IOS and IOS XE devices by exploiting improper HTTP method validation in the web management interface. The web UI fails to distinguish between legitimate POST requests that should carry state-changing operations and GET requests that should only retrieve data. This architectural flaw means that configuration changes can be embedded in URL parameters and executed when an authenticated administrator visits a crafted link.

The attack requires social engineering to convince an administrator with an active authenticated session to click a malicious link. Once clicked, the browser automatically sends the request with the administrator's session credentials, allowing the attacker's configuration changes to be applied with full administrative privileges.

Root Cause

The root cause of this vulnerability lies in improper authorization handling (CWE-285) and missing CSRF protections (CWE-352) within the Cisco IOS/IOS XE web UI. The application incorrectly accepts configuration changes via HTTP GET requests instead of enforcing the use of POST requests with proper CSRF tokens. This violates secure design principles that state GET requests should be idempotent and not cause state changes on the server.

The absence of anti-CSRF tokens or same-origin validation allows any website to forge requests that appear to come from authenticated administrators, as the browser automatically includes session cookies with cross-origin requests to the device's web interface.

Attack Vector

The attack is network-based and requires user interaction from an authenticated administrator. An attacker would craft a malicious URL containing device configuration commands embedded as GET parameters. This URL could be delivered through phishing emails, malicious websites, or embedded in legitimate-looking content.

When an administrator with an active session to the Cisco device's web UI clicks the link, their browser sends the request along with their authentication cookies. The web UI processes this as a legitimate configuration change request, applying the attacker's specified modifications to the device.

Potential attack scenarios include:

• Modifying access control lists (ACLs) to allow unauthorized traffic
• Creating rogue administrative accounts
• Disabling security features or logging
• Changing routing configurations to redirect traffic
• Modifying SNMP community strings or credentials

Detection Methods for CVE-2024-20414

Indicators of Compromise

• Unexpected configuration changes in device running configurations without corresponding authorized change records
• Web UI access logs showing GET requests that contain configuration parameters
• Configuration changes originating from unusual source IP addresses or during non-standard hours
• Evidence of administrators being directed to unfamiliar links prior to unauthorized changes

Detection Strategies

• Monitor web UI access logs for HTTP GET requests containing configuration command parameters
• Implement configuration change monitoring and alerting through Cisco Smart Call Home or syslog
• Compare running and startup configurations regularly to detect unauthorized modifications
• Review authentication logs for sessions followed by suspicious configuration changes

Monitoring Recommendations

• Enable comprehensive logging for all web UI access and configuration changes
• Deploy network security monitoring to detect suspicious links targeting internal Cisco device management interfaces
• Implement Security Information and Event Management (SIEM) rules to correlate web UI access with configuration changes
• Use Cisco Configuration Archive features to maintain configuration history for forensic analysis

How to Mitigate CVE-2024-20414

Immediate Actions Required

• Apply Cisco-provided security patches as specified in the Cisco Security Advisory
• Disable the web UI if not required for device management operations
• Restrict web UI access to trusted management networks only using ACLs
• Educate administrators about CSRF attacks and the importance of not clicking unknown links while authenticated to network devices

Patch Information

Cisco has released software updates that address this vulnerability. Organizations should consult the Cisco Security Advisory for specific fixed software versions and upgrade paths based on their current IOS or IOS XE version. Given the extensive list of affected versions spanning from 3.2.0se through 17.13.1a, organizations should verify their specific version against the advisory's comprehensive affected versions list.

Workarounds

• Disable the HTTP server feature if web UI management is not required using no ip http server and no ip http secure-server commands
• Implement strict ACLs to limit web UI access to specific management workstations and networks
• Use out-of-band management networks that are isolated from general user traffic
• Configure session timeouts to minimize the window of opportunity for CSRF attacks

# Disable web UI to eliminate the attack surface
configure terminal
no ip http server
no ip http secure-server
end
write memory

# Or restrict access if web UI is required
configure terminal
ip http access-class 10
access-list 10 permit 192.168.1.0 0.0.0.255
access-list 10 deny any
end
write memory