CVE-2019-25671: VA MAX 8.3.4 RCE Vulnerability

CVE-2019-25671 Overview

CVE-2019-25671 is a remote code execution vulnerability affecting VA MAX 8.3.4 that allows authenticated attackers to execute arbitrary commands on the underlying system. The vulnerability exists due to improper input validation in the changeip.php endpoint, where shell metacharacters can be injected into the mtu_eth0 parameter. This command injection flaw enables attackers to execute commands with the privileges of the apache user, potentially leading to full system compromise.

Critical Impact

Authenticated attackers can achieve remote code execution by injecting shell metacharacters, allowing arbitrary command execution as the apache user and potential full system compromise.

Affected Products

• VA MAX 8.3.4

Discovery Timeline

• 2026-04-05 - CVE CVE-2019-25671 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2019-25671

Vulnerability Analysis

This vulnerability is a command injection flaw that occurs when the application fails to properly sanitize user-supplied input before passing it to shell commands. The changeip.php endpoint accepts POST requests containing a mtu_eth0 parameter, which is intended to configure network interface MTU settings. However, the application does not adequately filter shell metacharacters from this input, allowing attackers to break out of the intended command context and inject arbitrary shell commands.

When an authenticated user submits a crafted POST request with malicious payload in the mtu_eth0 field, the injected commands are executed by the web server process running under the apache user context. This exploitation path requires valid authentication credentials, but once obtained, provides direct command execution capabilities on the target system.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization in the changeip.php script. The mtu_eth0 parameter is processed without proper escaping or filtering of shell metacharacters such as semicolons (;), pipes (|), backticks (`), and command substitution syntax ($()). This allows attackers to chain additional commands to the legitimate MTU configuration command, resulting in arbitrary command execution.

Attack Vector

The attack is network-based and requires the attacker to have valid authentication credentials for the VA MAX web interface. The attacker sends a specially crafted POST request to the changeip.php endpoint with shell metacharacters embedded in the mtu_eth0 parameter. When the server processes this request, the injected commands are executed with the privileges of the apache user.

For detailed technical information and proof-of-concept details, refer to Exploit-DB #46348 and the VulnCheck Advisory.

Detection Methods for CVE-2019-25671

Indicators of Compromise

• Unusual POST requests to /changeip.php containing shell metacharacters (;, |, `, $()) in the mtu_eth0 parameter
• Unexpected process spawning by the apache user, particularly shell interpreters or network utilities
• Web server logs showing malformed or suspicious MTU values in request parameters
• Anomalous network connections originating from the apache user context

Detection Strategies

• Monitor HTTP POST requests to changeip.php for shell metacharacter patterns in form parameters
• Implement web application firewall (WAF) rules to detect command injection attempts in MTU-related parameters
• Review apache access and error logs for suspicious requests targeting network configuration endpoints
• Deploy endpoint detection and response (EDR) solutions to identify command execution anomalies

Monitoring Recommendations

• Enable detailed logging for the VA MAX web application, particularly for network configuration endpoints
• Configure alerts for process execution chains originating from web server processes
• Monitor for reverse shell indicators such as unexpected outbound connections from the web server
• Implement file integrity monitoring on critical system directories

How to Mitigate CVE-2019-25671

Immediate Actions Required

• Restrict access to the VA MAX web interface to trusted networks only using firewall rules
• Review and audit user accounts with access to the VA MAX administration interface
• Implement strong authentication mechanisms and enforce principle of least privilege
• Consider taking the vulnerable endpoint offline until a patch is available

Patch Information

Consult the vendor for available security patches or updated firmware versions that address this vulnerability. Review the VulnCheck Advisory for the latest remediation guidance.

Workarounds

• Implement network-level access controls to limit who can reach the VA MAX web interface
• Deploy a web application firewall (WAF) with rules to block command injection patterns in POST parameters
• Disable or restrict access to the changeip.php endpoint if network configuration via web interface is not required
• Monitor and log all access to administrative endpoints for forensic purposes

# Example iptables rule to restrict access to VA MAX web interface
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP