CVE-2024-26001: Charx SEC-3000 Buffer Overflow Vulnerability

CVE-2024-26001 Overview

CVE-2024-26001 is an out-of-bounds write vulnerability affecting Phoenix Contact CHARX SEC electric vehicle charging controllers. An unauthenticated remote attacker can write memory out of bounds due to improper input validation in the MQTT stack. While memory randomization provides some mitigation against brute force exploitation attempts, the vulnerability remains a significant threat to industrial charging infrastructure.

Critical Impact

Unauthenticated remote attackers can exploit improper input validation in the MQTT stack to write memory out of bounds, potentially achieving remote code execution on affected EV charging controllers.

Affected Products

• Phoenix Contact CHARX SEC-3000 (firmware)
• Phoenix Contact CHARX SEC-3050 (firmware)
• Phoenix Contact CHARX SEC-3100 (firmware)
• Phoenix Contact CHARX SEC-3150 (firmware)

Discovery Timeline

• 2024-03-12 - CVE-2024-26001 published to NVD
• 2025-01-24 - Last updated in NVD database

Technical Details for CVE-2024-26001

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), affecting the MQTT messaging protocol implementation in Phoenix Contact CHARX SEC charging controllers. The flaw resides in the input validation routines of the MQTT stack, where malformed or specially crafted MQTT messages can cause the firmware to write data beyond the boundaries of allocated memory buffers.

The MQTT protocol is commonly used in IoT and industrial environments for lightweight machine-to-machine communication. In the context of EV charging infrastructure, MQTT facilitates communication between charging stations, backend systems, and management platforms. The vulnerability allows network-accessible attackers to send malicious MQTT packets that bypass input validation checks, triggering out-of-bounds memory writes.

Root Cause

The root cause is improper input validation in the MQTT stack implementation. When processing MQTT messages, the firmware fails to adequately validate the size and boundaries of input data before writing to memory buffers. This allows an attacker to craft MQTT packets with malicious payloads that exceed expected buffer sizes, causing memory corruption.

Attack Vector

The attack can be executed remotely over the network without authentication. An attacker with network access to the MQTT service on affected devices can send specially crafted MQTT messages to trigger the out-of-bounds write condition. While the advisory notes that brute force attacks are not always successful due to Address Space Layout Randomization (ASLR) or similar memory randomization techniques, persistent attackers may eventually achieve successful exploitation through repeated attempts.

The attack does not require any privileges or user interaction, making it particularly dangerous in environments where these charging controllers are exposed to untrusted networks.

Detection Methods for CVE-2024-26001

Indicators of Compromise

• Unexpected crashes or restarts of CHARX SEC charging controllers
• Anomalous MQTT traffic patterns targeting charging infrastructure
• Memory corruption indicators in device logs or crash dumps
• Unusual network connections from charging controllers to external addresses

Detection Strategies

• Monitor MQTT traffic (typically port 1883 or 8883) for malformed or unusually large packets directed at CHARX SEC devices
• Implement network intrusion detection rules for out-of-bounds write exploit signatures targeting MQTT services
• Deploy network segmentation monitoring to detect unauthorized access attempts to charging infrastructure
• Enable logging on CHARX SEC devices to capture crash events and anomalous behavior

Monitoring Recommendations

• Implement continuous network monitoring for all Phoenix Contact CHARX SEC device communications
• Establish baseline MQTT traffic patterns and alert on deviations
• Monitor device health metrics for signs of memory corruption or instability
• Review access logs for unauthorized connection attempts to MQTT services

How to Mitigate CVE-2024-26001

Immediate Actions Required

• Restrict network access to affected CHARX SEC devices using firewalls or network segmentation
• Disable MQTT services if not required for operations
• Ensure charging controllers are not directly exposed to the internet
• Apply firmware updates from Phoenix Contact as soon as they become available
• Monitor the VDE Security Advisory VDE-2024-011 for updates

Patch Information

Organizations should consult the VDE Security Advisory VDE-2024-011 for official patch information and firmware updates from Phoenix Contact. Apply all security updates to CHARX SEC-3000, CHARX SEC-3050, CHARX SEC-3100, and CHARX SEC-3150 devices as they become available.

Workarounds

• Implement strict network segmentation to isolate charging infrastructure from untrusted networks
• Configure firewall rules to restrict MQTT access to authorized management systems only
• Deploy a VPN or other secure tunnel for remote management of charging controllers
• Consider implementing MQTT authentication and TLS encryption where supported

# Example firewall rule to restrict MQTT access (adapt to your environment)
# Allow MQTT only from management network
iptables -A INPUT -p tcp --dport 1883 -s 10.0.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 1883 -j DROP

# Block all external access to charging controller network segment
iptables -A FORWARD -d 10.0.200.0/24 -i eth0 -j DROP