CVE-2023-6691: Cambium ePMP Force 300-25 RCE Vulnerability

CVE-2023-6691 Overview

CVE-2023-6691 is a code injection vulnerability affecting Cambium ePMP Force 300-25 wireless network devices running firmware version 4.7.0.1. This vulnerability allows an attacker with local access to inject and execute arbitrary code on the affected device, potentially leading to remote code execution and obtaining root privileges on the system.

The Cambium ePMP (Enterprise Point-to-Multipoint) Force 300-25 is a high-performance wireless broadband solution commonly deployed in enterprise networks, ISP infrastructure, and critical communications systems. The exploitation of this vulnerability could allow attackers to fully compromise the device and potentially use it as a pivot point for further attacks within the network.

Critical Impact

Successful exploitation enables attackers to achieve remote code execution with root privileges, allowing complete device takeover and potential lateral movement within network infrastructure.

Affected Products

• Cambium Networks ePMP Force 300-25 Firmware version 4.7.0.1
• Cambium Networks ePMP Force 300-25 Hardware

Discovery Timeline

• 2023-12-18 - CVE-2023-6691 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-6691

Vulnerability Analysis

This vulnerability is classified as a Code Injection flaw (CWE-94), which occurs when an application constructs code segments using externally-influenced input without properly neutralizing special elements. In the case of the Cambium ePMP Force 300-25, the firmware fails to adequately validate or sanitize input before incorporating it into executable code paths.

The local attack vector requires the attacker to have some level of access to the target system. Once this initial access is obtained, the attacker can leverage the code injection vulnerability to execute arbitrary commands with elevated privileges. The successful exploitation results in complete compromise of the device's confidentiality, integrity, and availability.

For detailed technical information, refer to the CISA ICS Advisory ICSA-23-348-01.

Root Cause

The root cause of CVE-2023-6691 stems from improper input validation within the firmware's code execution pathways. The affected firmware version 4.7.0.1 contains insufficient sanitization of user-controllable input before it is incorporated into dynamically generated code or command sequences. This allows specially crafted input to break out of the intended context and execute attacker-controlled code with the privileges of the vulnerable process, ultimately leading to root-level access.

Attack Vector

The attack vector for this vulnerability is local, meaning an attacker requires some form of existing access to the target device or network segment. The exploitation process involves:

1. Initial Access: The attacker must first obtain local access to the Cambium ePMP Force 300-25 device, potentially through the web management interface, SSH, or other available services.

2. Payload Injection: Once access is established, the attacker crafts malicious input designed to escape the normal execution context and inject arbitrary code.

3. Code Execution: The injected code is executed by the vulnerable component, running with elevated privileges.

4. Privilege Escalation: The attacker achieves root-level access on the device, enabling full control over the system.

The vulnerability requires low privileges to exploit and does not require user interaction, making it relatively straightforward to leverage once initial access is obtained.

Detection Methods for CVE-2023-6691

Indicators of Compromise

• Unexpected processes running with root privileges on ePMP Force 300-25 devices
• Anomalous command execution patterns in device logs
• Unauthorized configuration changes to network settings or firmware parameters
• Suspicious authentication attempts or successful logins from unexpected sources
• Unusual network traffic originating from the affected device

Detection Strategies

• Monitor firmware version inventory across all Cambium ePMP devices and alert on version 4.7.0.1
• Implement network segmentation monitoring to detect lateral movement from compromised devices
• Deploy intrusion detection systems (IDS) with rules targeting abnormal command execution patterns
• Enable comprehensive logging on all ePMP devices and forward logs to a SIEM solution for analysis

Monitoring Recommendations

• Establish baseline behavior for Cambium ePMP devices to identify anomalous activity
• Configure alerts for privilege escalation attempts or unexpected root-level access
• Monitor network traffic patterns for command-and-control indicators originating from wireless infrastructure
• Implement file integrity monitoring on critical firmware and configuration files

How to Mitigate CVE-2023-6691

Immediate Actions Required

• Identify all Cambium ePMP Force 300-25 devices running firmware version 4.7.0.1 in your environment
• Review the CISA ICS Advisory ICSA-23-348-01 for vendor-specific guidance
• Restrict local access to affected devices to only essential personnel until patches are applied
• Implement network segmentation to isolate vulnerable devices from critical infrastructure

Patch Information

Organizations should consult the CISA ICS Advisory ICSA-23-348-01 for official remediation guidance from Cambium Networks. Upgrade to the latest firmware version that addresses this vulnerability as soon as patches become available. Always verify firmware authenticity before installation and follow vendor-recommended upgrade procedures.

Workarounds

• Implement strict network access controls to limit who can reach the device's management interfaces
• Disable unnecessary services and protocols on affected devices to reduce the attack surface
• Deploy network-level filtering to restrict access to known trusted IP addresses
• Enable strong authentication mechanisms and enforce complex password policies
• Monitor device activity closely for signs of exploitation until a patch can be applied

# Configuration example - Network Access Restriction
# Restrict management interface access to trusted networks only
# Consult Cambium documentation for device-specific commands

# Example firewall rule to restrict access to management port
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Example firewall rule to restrict SSH access
iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j DROP