CVE-2024-8684: Revolution Pi OS Command Injection Flaw

CVE-2024-8684 Overview

CVE-2024-8684 is an OS command injection vulnerability in KUNBUS GmbH Revolution Pi version 2022-07-28-revpi-buster. The flaw resides in the php/dal.php endpoint, which fails to sanitize input passed through the arrSaveConfig parameter. An authenticated attacker can inject arbitrary operating system commands that execute on the industrial controller. Revolution Pi devices are open-source industrial PCs based on Raspberry Pi hardware, commonly deployed in operational technology (OT) and industrial automation environments. This vulnerability is tracked under CWE-78, Improper Neutralization of Special Elements used in an OS Command.

Critical Impact
Authenticated attackers can execute arbitrary OS commands on Revolution Pi controllers, compromising industrial process integrity and availability.

Affected Products

KUNBUS Revolution Pi
Revolution Pi image version 2022-07-28-revpi-buster
Deployments exposing the Revolution Pi web management interface

Discovery Timeline

2025-02-10 - CVE-2024-8684 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-8684

Vulnerability Analysis

The vulnerability exists in the Revolution Pi web management interface, specifically in the php/dal.php handler. The arrSaveConfig parameter accepts user-controlled input that is passed to an OS command execution function without adequate sanitization or escaping. An authenticated attacker with low privileges submits crafted values in the arrSaveConfig parameter, appending shell metacharacters such as semicolons, pipes, or backticks. The web server process, typically running with elevated permissions on the Revolution Pi image, executes the injected commands.

Exploitation results in high impact on integrity and availability, with lower confidentiality impact. Because Revolution Pi devices operate as programmable logic controllers in industrial environments, command execution can disrupt physical processes, modify configuration files, install persistence, or pivot into segmented OT networks.

Root Cause

The root cause is missing input neutralization before invoking a shell interpreter. The application concatenates the arrSaveConfig parameter into a system command string rather than using parameterized execution or an allowlist. This is a classic CWE-78 pattern in PHP applications that call shell_exec, system, exec, or backtick operators with unfiltered request data.

Attack Vector

The attack requires network access to the Revolution Pi management interface and valid low-privilege credentials. Attackers submit an HTTP POST request to php/dal.php containing shell metacharacters in arrSaveConfig. Refer to the INCIBE Security Notice for the coordinated advisory covering this and related Revolution Pi vulnerabilities.

Detection Methods for CVE-2024-8684

Indicators of Compromise

HTTP POST requests to /php/dal.php containing shell metacharacters such as ;, |, &, `, or $() in the arrSaveConfig parameter
Unexpected child processes spawned by the web server user on the Revolution Pi device
New or modified cron jobs, systemd units, or SSH authorized_keys entries following authenticated web sessions
Outbound connections from Revolution Pi devices to unfamiliar hosts

Detection Strategies

Deploy web application logging on the Revolution Pi to capture all requests to php/dal.php with full parameter values for post-hoc analysis
Correlate authenticated web sessions with process execution telemetry from the underlying Linux host to identify command spawning
Alert on any invocation of shells such as /bin/sh or /bin/bash originating from the PHP interpreter process

Monitoring Recommendations

Forward Revolution Pi syslog and web server access logs to a central log platform for anomaly detection
Monitor for authentication attempts against the Revolution Pi web interface from unexpected source IP addresses
Baseline normal command execution on the device and alert on deviations

How to Mitigate CVE-2024-8684

Immediate Actions Required

Restrict network access to the Revolution Pi web management interface using firewall rules, allowing only trusted administrative hosts
Rotate credentials for all Revolution Pi user accounts and enforce strong, unique passwords
Audit user accounts on affected devices and remove unused or default accounts
Isolate Revolution Pi devices in a dedicated OT network segment separated from corporate IT networks

Patch Information

KUNBUS has coordinated disclosure through INCIBE-CERT. Consult the INCIBE Security Notice for vendor remediation guidance and updated Revolution Pi images. Upgrade devices from the vulnerable 2022-07-28-revpi-buster image to the latest KUNBUS-supplied release.

Workarounds

Disable the Revolution Pi web management interface if it is not required for operations
Place the management interface behind a VPN or bastion host requiring multi-factor authentication
Implement a reverse proxy that filters requests to php/dal.php and blocks payloads containing shell metacharacters
Apply defense-in-depth by running the web server under a least-privilege account where feasible

bash

# Example iptables rule restricting web interface access to an admin subnet
iptables -A INPUT -p tcp --dport 80 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP