What precautions should be taken when using exec() function in PHP to send faxes?

When using the exec() function in PHP to send faxes, it is important to sanitize user input to prevent command injection attacks. This can be done by validating and escaping any user-provided input before passing it to the exec() function. Additionally, it is recommended to limit the commands that can be executed and use absolute paths for any external commands being called. 

$user_input = $_POST['fax_number']; // Example user input

// Sanitize user input
$fax_number = escapeshellarg($user_input);

// Limit the commands that can be executed
$command = "/path/to/fax/sending/script " . $fax_number;

// Use absolute paths for external commands
exec($command);

Keywords

exec function security risks command injection escapeshellarg shell_exec

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