CVE-2024-48849: FLXEON Auth Bypass Vulnerability

CVE-2024-48849 Overview

CVE-2024-48849 is a Missing Origin Validation in WebSockets vulnerability affecting ABB FLXEON devices. The vulnerability stems from insufficient session management that fails to prevent unauthorized HTTPS requests. This security flaw allows attackers to potentially hijack WebSocket connections and perform unauthorized actions on affected systems.

Critical Impact

Attackers can exploit insufficient origin validation in WebSocket connections to bypass session management controls, potentially leading to unauthorized data modification and system disruption on FLXEON devices through version 9.3.4.

Affected Products

• ABB FLXEON through version 9.3.4

Discovery Timeline

• 2025-01-29 - CVE CVE-2024-48849 published to NVD
• 2025-01-29 - Last updated in NVD database

Technical Details for CVE-2024-48849

Vulnerability Analysis

This vulnerability is classified under CWE-1385 (Missing Origin Validation in WebSockets), which occurs when a WebSocket endpoint does not properly verify the origin of incoming requests. Without proper origin validation, an attacker can craft malicious web pages that establish WebSocket connections to vulnerable FLXEON devices, effectively bypassing the same-origin policy protections that browsers typically enforce for standard HTTP requests.

The insufficient session management compounds this issue by failing to adequately authenticate and authorize HTTPS requests. This combination allows attackers to potentially perform cross-site WebSocket hijacking attacks, where a victim's browser is tricked into making authenticated WebSocket connections to the target FLXEON device on the attacker's behalf.

Root Cause

The root cause of this vulnerability lies in the improper implementation of origin validation mechanisms within the FLXEON WebSocket handler. When WebSocket connections are established, the server should validate the Origin header to ensure requests originate from trusted domains. The FLXEON devices through version 9.3.4 fail to properly implement this validation, combined with weak session management that does not adequately prevent unauthorized requests from being processed.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no user interaction or authentication. An attacker can exploit this vulnerability by:

1. Hosting a malicious webpage that contains JavaScript code designed to establish WebSocket connections to the target FLXEON device
2. Luring a victim who has network access to the FLXEON device to visit the malicious page
3. The victim's browser establishes a WebSocket connection to the FLXEON device, which does not validate the origin of the request
4. The attacker can then leverage this connection to send unauthorized commands or exfiltrate data through the victim's authenticated session

The vulnerability can be exploited remotely over the network with low attack complexity, potentially resulting in high impact to both integrity and availability of the affected system.

Detection Methods for CVE-2024-48849

Indicators of Compromise

• WebSocket connections originating from unexpected or untrusted external domains
• Unusual patterns of WebSocket traffic to FLXEON devices from internal workstations
• Multiple failed or anomalous session establishment attempts followed by successful connections
• HTTPS requests to FLXEON management interfaces from unexpected sources

Detection Strategies

• Monitor WebSocket connection logs for connections with suspicious or missing Origin headers
• Implement network-level monitoring for unusual traffic patterns to FLXEON devices
• Deploy web application firewalls capable of inspecting WebSocket traffic for anomalies
• Review authentication logs for session hijacking indicators or unauthorized access attempts

Monitoring Recommendations

• Enable detailed logging on FLXEON devices to capture WebSocket connection metadata
• Configure SIEM alerts for WebSocket connections from external or unexpected origins
• Monitor network traffic to FLXEON devices for unusual connection patterns or data exfiltration attempts
• Regularly audit access logs for signs of cross-site WebSocket hijacking activity

How to Mitigate CVE-2024-48849

Immediate Actions Required

• Review and restrict network access to FLXEON devices to trusted networks and IP addresses only
• Implement network segmentation to isolate FLXEON devices from general user workstations
• Deploy a reverse proxy or web application firewall with proper origin validation in front of FLXEON devices
• Monitor for abnormal WebSocket connection activity and investigate any suspicious patterns

Patch Information

ABB has released a security advisory addressing this vulnerability. Organizations should consult the ABB Technical Document for specific patch information and update instructions. Upgrade FLXEON devices to a version newer than 9.3.4 when available from ABB.

Workarounds

• Restrict network access to FLXEON WebSocket interfaces using firewall rules to allow only trusted IP addresses
• Implement a reverse proxy that enforces strict Origin header validation before forwarding requests to FLXEON devices
• Consider disabling WebSocket functionality if not operationally required until patches are applied
• Deploy network monitoring to detect and alert on cross-site WebSocket hijacking attempts

# Example firewall rule to restrict access to FLXEON devices
# Adjust IP addresses and ports according to your environment
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP