CVE-2020-37123: Pinger 1.0 Remote Code Execution Flaw

CVE-2020-37123 Overview

CVE-2020-37123 is a critical remote code execution vulnerability affecting Pinger 1.0, a network monitoring application. The vulnerability allows remote attackers to inject arbitrary shell commands through the ping and socket parameters in the ping.php file. Due to insufficient input sanitization, attackers can append shell metacharacters to these parameters, enabling the creation of arbitrary PHP files and execution of system commands on the underlying server.

Critical Impact

Unauthenticated remote attackers can achieve full system compromise by exploiting unsanitized input parameters to execute arbitrary commands and write malicious files to the web server.

Affected Products

• Pinger 1.0

Discovery Timeline

• 2026-02-05 - CVE-2020-37123 published to NVD
• 2026-02-05 - Last updated in NVD database

Technical Details for CVE-2020-37123

Vulnerability Analysis

This vulnerability is classified as CWE-78 (OS Command Injection), one of the most severe vulnerability classes that frequently leads to complete system compromise. The flaw exists in the ping.php component of Pinger 1.0, where user-supplied input from the ping and socket parameters is passed directly to system shell commands without proper sanitization or validation.

The network-accessible attack vector means this vulnerability can be exploited remotely without any authentication requirements or user interaction. An attacker with network access to a vulnerable Pinger installation can craft malicious HTTP requests containing shell metacharacters (such as ;, |, &&, or backticks) to break out of the intended command context and execute arbitrary commands with the privileges of the web server process.

Root Cause

The root cause of CVE-2020-37123 is the complete absence of input sanitization on the ping and socket parameters within the ping.php script. The application directly concatenates user-controlled input into shell command strings without escaping special characters or validating the input format. This allows attackers to inject shell metacharacters that terminate the intended command and execute attacker-controlled commands.

Proper remediation would require implementing strict input validation (allowlisting valid IP addresses and hostnames), using parameterized command execution functions that prevent command injection, or employing PHP's escapeshellarg() and escapeshellcmd() functions to neutralize shell metacharacters.

Attack Vector

The attack is executed via network-based HTTP requests to the vulnerable ping.php endpoint. An attacker crafts a malicious request containing shell metacharacters appended to the ping or socket parameters. For example, an attacker could supply input like 127.0.0.1; cat /etc/passwd to the ping parameter. The semicolon terminates the legitimate ping command, and the subsequent command is then executed by the shell.

More sophisticated attacks involve writing PHP webshells to the server by injecting commands like echo '<?php system($_GET["cmd"]); ?>' > shell.php, providing persistent backdoor access to the compromised system. The vulnerability requires no authentication and can be exploited by any attacker with network access to the application.

The vulnerability mechanism exploits insufficient input sanitization in the ping.php script. When user input containing shell metacharacters is passed to system commands, the shell interprets these characters as command separators or redirectors rather than literal input. This allows attackers to chain arbitrary commands after the intended ping operation. For detailed technical analysis and proof-of-concept details, refer to Exploit-DB #48323 and the VulnCheck Advisory for Pinger.

Detection Methods for CVE-2020-37123

Indicators of Compromise

• Unusual HTTP requests to ping.php containing shell metacharacters (;, |, &&, ||, backticks, $())
• Newly created PHP files in the web root directory with suspicious content or generic names like shell.php
• Web server process spawning unexpected child processes such as /bin/sh, /bin/bash, or system utilities
• Outbound network connections from the web server to unfamiliar external IP addresses

Detection Strategies

• Monitor web server access logs for requests to ping.php with parameters containing shell metacharacters or encoded special characters
• Implement web application firewall (WAF) rules to detect and block command injection patterns in HTTP parameters
• Deploy file integrity monitoring on web directories to alert on unauthorized file creation or modification
• Analyze process execution chains to identify web server processes spawning shells or system utilities

Monitoring Recommendations

• Enable verbose logging for the web server and review logs for anomalous requests to ping.php
• Configure host-based intrusion detection systems (HIDS) to monitor for suspicious process execution from web server contexts
• Implement network traffic analysis to detect command-and-control communications or data exfiltration attempts
• Set up alerts for new file creation in web-accessible directories

How to Mitigate CVE-2020-37123

Immediate Actions Required

• Remove or disable the Pinger application immediately if it is not essential to operations
• Restrict network access to the application using firewall rules to limit exposure to trusted IP addresses only
• If the application must remain active, implement a web application firewall (WAF) with command injection detection rules
• Conduct a forensic review of affected systems to identify any signs of compromise or unauthorized file creation

Patch Information

No official vendor patch has been identified in the available CVE data. The Pinger project repository is available on GitHub. Organizations using Pinger 1.0 should check the repository for any security updates or consider migrating to alternative network monitoring solutions with better security practices.

For additional technical details and vulnerability analysis, refer to the VulnCheck Advisory for Pinger.

Workarounds

• Disable or remove the ping.php script from the web server if the ping functionality is not required
• Implement manual input validation by modifying the source code to only accept valid IP addresses or hostnames using strict regex patterns
• Add escapeshellarg() and escapeshellcmd() PHP functions to all user-supplied input before passing to shell commands
• Deploy the application behind a reverse proxy with request filtering capabilities to block malicious input patterns

# Example: Restrict access to ping.php using Apache .htaccess
# Add to .htaccess in the Pinger web directory
<Files "ping.php">
    Order Deny,Allow
    Deny from all
    # Allow only from specific trusted IP
    Allow from 192.168.1.0/24
</Files>