CVE-2023-28343: Apsystems ECU Firmware RCE Vulnerability

CVE-2023-28343 Overview

CVE-2023-28343 is a critical OS command injection vulnerability affecting Altenergy Power Control Software C1.2.5. The flaw exists in the index.php/management/set_timezone endpoint where the timezone parameter fails to properly sanitize shell metacharacters before being processed by the set_timezone function in models/management_model.php. This allows unauthenticated remote attackers to execute arbitrary operating system commands on the underlying server.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary system commands on affected APSystems Energy Communication Unit devices, potentially leading to complete system compromise, data exfiltration, or lateral movement within critical energy infrastructure networks.

Affected Products

• APSystems Energy Communication Unit Firmware version C1.2.5
• APSystems Energy Communication Unit (hardware)
• Altenergy Power Control Software C1.2.5

Discovery Timeline

• 2023-03-14 - CVE-2023-28343 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-28343

Vulnerability Analysis

This command injection vulnerability (CWE-78) resides in the timezone management functionality of the Altenergy Power Control Software. When a user submits a timezone configuration change through the web interface, the application passes the timezone parameter directly to system shell functions without adequate input validation or sanitization.

The vulnerable code path flows from the index.php/management/set_timezone endpoint to the set_timezone function within models/management_model.php. Because the application does not filter shell metacharacters (such as semicolons, pipes, backticks, or ampersands), an attacker can append malicious commands to the timezone value that will be executed with the privileges of the web server process.

The vulnerability is particularly dangerous because it requires no authentication, can be exploited remotely over the network, and affects critical energy infrastructure equipment used for solar power system monitoring and management.

Root Cause

The root cause of this vulnerability is improper input validation in the set_timezone function within models/management_model.php. The application directly incorporates user-supplied input from the timezone parameter into shell commands without implementing proper sanitization, escaping, or validation. This violates fundamental secure coding principles for handling user input that interacts with system shells.

Attack Vector

The attack vector is network-based and requires no user interaction or authentication. An attacker can craft a malicious HTTP request to the index.php/management/set_timezone endpoint, embedding shell metacharacters and arbitrary commands within the timezone parameter. When the server processes this request, the injected commands are executed on the underlying operating system.

For example, an attacker might inject commands using shell metacharacters like semicolons (;), backticks, or command substitution syntax to chain malicious commands after the legitimate timezone value. The commands execute with the same privileges as the web application, typically the web server user.

Detailed technical information and proof-of-concept examples are available in the GitHub Disclosure and the Packet Storm Exploit Report.

Detection Methods for CVE-2023-28343

Indicators of Compromise

• HTTP requests to /index.php/management/set_timezone containing shell metacharacters (;, |, &, backticks, $()) in the timezone parameter
• Unusual process spawning from the web server process (Apache/Nginx worker processes)
• Unexpected outbound network connections from the Energy Communication Unit
• New or modified files in web-accessible directories or system locations
• Anomalous system commands in web server access logs or command history

Detection Strategies

• Deploy web application firewall (WAF) rules to detect and block command injection patterns in HTTP parameters
• Monitor web server logs for requests to /index.php/management/set_timezone with suspicious payload patterns
• Implement network intrusion detection signatures for known command injection exploit attempts targeting this endpoint
• Configure endpoint detection and response (EDR) solutions to alert on shell command execution from web server processes

Monitoring Recommendations

• Enable verbose logging on APSystems Energy Communication Units and forward logs to a SIEM platform
• Monitor for anomalous system call patterns or process trees originating from web server contexts
• Establish baseline network behavior for Energy Communication Units and alert on deviations
• Implement file integrity monitoring on critical system files and web application directories

How to Mitigate CVE-2023-28343

Immediate Actions Required

• Restrict network access to affected APSystems Energy Communication Units using firewall rules, limiting access to trusted IP addresses only
• Place vulnerable devices behind a VPN or network segmentation to prevent direct internet exposure
• Monitor affected devices for signs of compromise and investigate any suspicious activity
• Audit access logs for evidence of exploitation attempts against the /index.php/management/set_timezone endpoint

Patch Information

At the time of this writing, no vendor-supplied patch information is available in the CVE data. Organizations should contact APSystems directly through their official website to inquire about firmware updates that address this vulnerability. Monitor vendor security advisories for patch releases.

Workarounds

• Implement network-level access controls to restrict access to the web management interface to authorized administrators only
• Deploy a reverse proxy or web application firewall in front of the device to filter malicious input and block command injection attempts
• If the timezone functionality is not required, consider disabling access to the /management/set_timezone endpoint at the network or application level
• Isolate affected devices on a dedicated management VLAN with strict access controls

# Example iptables rule to restrict access to the management interface
# Allow access only from trusted management subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

# Example nginx location block to block access to vulnerable endpoint
# location ~ /index.php/management/set_timezone {
#     deny all;
#     return 403;
# }