Zploit 0-Day Shell

:: Editing File: register.php

<?php
include('db_config.php');
include('login_header.php');
?>

<div id="page-content">
    <div class="login-form">
        <div class="container">
            <div class="row">
                <div class="col s12">
                    <div class="section-title">
                        
                        <center><a href="index.php"><img src="logo/logo.png" width="350px;"></a></center><br><br>
                        
                        <span class="theme-secondary-color">Register</span> Account
                        
                        <?php 
                            if (isset($_GET['error'])) {
                                echo '<p style="color:red;">' . htmlspecialchars($_GET['error']) . '</p>';
                            }
                        ?>
                    </div>
                </div>
            </div>
            <div class="row">
                <form class="col s12" action="register_action.php" method="POST">
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4">
                            <input type="text" class="validate" id="username" name="username" required>
                            <label for="username">Enter Username</label>
                        </div>
                    </div>
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4">
                            <input type="email" class="validate" autocomplete="off" id="email" name="email" required>
                            <label for="email">Enter Email ID</label>
                        </div>
                    </div>
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4">
                            <input type="tel" class="validate" id="mobile_no" name="mobile_no" required>
                            <label for="mobile_no">Enter Mobile No</label>
                        </div>
                    </div>
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4">
                            <input type="text" class="validate" id="occupation" name="occupation">
                            <label for="occupation">Occupation (Optional)</label>
                        </div>
                    </div>
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4">
                            <textarea id="message" name="message" class="materialize-textarea"></textarea>
                            <label for="message">Message (Optional)</label>
                        </div>
                    </div>
                    
                    <div class="row">
                        <div class="input-field col s12 m6 l4 offset-m3 offset-l4 center">
                            <button class="btn waves-effect waves-light" type="submit" name="action">
                                Register 
                                
                            </button>
                        </div>
                    </div>
                </form>
            </div>
            
            <div class="row center">
                <p>Already have an account? <a href="index.php">Login Here</a></p>
            </div>
            
        </div>
    </div>
</div>

<?php include('login_footer.php'); ?>