Cmd hijack vulnerability
Description
This application is vulnerable to Command Hijack attacks, a command/argument confusion vulnerability specific to Windows cmd.exe. Attackers can exploit this flaw by injecting path traversal sequences into commands, causing cmd.exe to execute arbitrary system executables instead of the intended program. For example, the command
cmd.exe /c "ping 127.0.0.1/../../../../../../../../../../windows/system32/calc.exe"will launch calc.exe instead of ping.exe. This vulnerability only affects Windows systems and occurs when user input is passed to cmd.exe without proper sanitization.
Remediation
Implement strict input validation and sanitization to prevent command injection attacks:<br/><br/><strong>1. Avoid using cmd.exe entirely:</strong> Use direct API calls or built-in language functions instead of shell commands whenever possible.<br/><br/><strong>2. Validate and sanitize all user input:</strong> Remove or reject path traversal sequences (../, .\) and other metacharacters before passing data to shell commands.<br/><br/><strong>3. Use proper escaping functions:</strong> For PHP applications, use <strong>escapeshellarg()</strong> to escape individual arguments rather than <strong>escapeshellcmd()</strong>, which is insufficient against this attack:<br/><pre>// Vulnerable code $ip = $_GET['ip']; exec("cmd.exe /c ping " . escapeshellcmd($ip)); // Secure code $ip = $_GET['ip']; exec("cmd.exe /c ping " . escapeshellarg($ip));</pre><br/><strong>4. Implement allowlisting:</strong> Restrict input to known-safe values using allowlists rather than denylists.<br/><br/><strong>5. Apply principle of least privilege:</strong> Run web server processes with minimal necessary permissions to limit the impact of successful exploitation.