Security Flaw in php form - php

Question

Apparently my php email form is full of security vulnerabilities, what can I do to fix them?
And what i mean by security flaws, that is hackers/bots being able to inject additional headers(eg bcc) into my form and send spam in my name
Any suggestions?
<?php
/*
* Template Name: Contact Form Page
*/
if(isset($_POST['submitted'])) {
//Check to make sure that the name field is not empty
if(trim($_POST['contactName']) === '') {
$nameError = __("You forgot to enter your name.", "site5framework");
$hasError = true;
} else {
$name = trim($_POST['contactName']);
}
//Check to make sure sure that a valid email address is submitted
if(trim($_POST['email']) === '') {
$emailError = __("You forgot to enter your email address.", "site5framework");
$hasError = true;
} else if (!eregi("^[A-Z0-9._%-]+#[A-Z0-9._%-]+\.[A-Z]{2,4}$", trim($_POST['email']))) {
$emailError = __("You entered an invalid email address.", "site5framework");
$hasError = true;
} else {
$email = trim($_POST['email']);
}
//Check to make sure comments were entered
if(trim($_POST['comments']) === '') {
$commentError = __("You forgot to enter your comments.", "site5framework");
$hasError = true;
} else {
if(function_exists('stripslashes')) {
$comments = stripslashes(trim($_POST['comments']));
} else {
$comments = trim($_POST['comments']);
}
}
//If there is no error, send the email
if(!isset($hasError)) {
$msg .= "------------User Info------------ \r\n"; //Title
$msg .= "User IP: ".$_SERVER["REMOTE_ADDR"]."\r\n"; //Sender's IP
$msg .= "Browser Info: ".$_SERVER["HTTP_USER_AGENT"]."\r\n"; //User agent
$msg .= "Referrer: ".$_SERVER["HTTP_REFERER"]; //Referrer
$emailTo = ''.of_get_option('sc_contact_email').'';
$subject = 'Contact Form Submission From '.$name;
$body = "Name: $name \n\nEmail: $email \n\nMessage: $comments \n\n $msg";
$headers = 'From: '.$name.' <'.$email.'>' . "\r\n" . 'Reply-To: ' . $email;
if(mail($emailTo, $subject, $body, $headers)) $emailSent = true;
}
}
get_header();
?>
<div id="content" class="container clearfix">
<!-- page header -->
<div class="container clearfix ">
<?php if(of_get_option('sc_contact_map') != '') { ?>
<!-- contact map -->
<div id="contact-map">
<?php echo of_get_option('sc_contact_map') ?>
</div>
<!-- end contact map -->
<?php } else if(of_get_option('sc_showpageheader') == '1' && get_post_meta($post->ID, 'snbpd_ph_disabled', true) != 'on' ) : ?>
<?php if(get_post_meta($post->ID, 'snbpd_phitemlink', true)!= '') : ?>
<?php
$thumbId = get_image_id_by_link ( get_post_meta($post->ID, 'snbpd_phitemlink', true) );
$thumb = wp_get_attachment_image_src($thumbId, 'page-header', false);
?>
<img class="intro-img" alt=" " src="<?php echo $thumb[0] ?>" alt="<?php the_title(); ?>" />
<?php elseif (of_get_option('sc_pageheaderurl') !='' ): ?>
<?php
$thumbId = get_image_id_by_link ( of_get_option('sc_pageheaderurl') );
$thumb = wp_get_attachment_image_src($thumbId, 'page-header', false);
?>
<img class="intro-img" alt=" " src="<?php echo $thumb[0] ?>" alt="<?php the_title(); ?>" />
<?php else: ?>
<img class="intro-img" alt=" " src="<?php echo get_template_directory_uri(); ?>/library/images/inner-page-bg.jpg" />
<?php endif ?>
<?php endif ?>
</div>
<!-- content -->
<div class="container">
<h1><?php the_title(); ?> <?php if ( !get_post_meta($post->ID, 'snbpd_pagedesc', true)== '') { ?>/<?php }?> <span><?php echo get_post_meta($post->ID, 'snbpd_pagedesc', true); ?></span></h1>
<article id="post-<?php the_ID(); ?>" <?php post_class('clearfix'); ?> role="article">
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div class="page-body clearfix">
<?php the_content(); ?>
</div>
<div class="one-third">
<div class="caddress"><strong><?php _e('Address:', 'site5framework') ?></strong> <?php echo of_get_option('sc_contact_address') ?></div>
<div class="cphone"><strong><?php _e('Phone:', 'site5framework') ?></strong> <?php echo of_get_option('sc_contact_phone') ?></div>
<div class="cphone"><strong><?php _e('Fax:', 'site5framework') ?></strong> <?php echo of_get_option('sc_contact_fax') ?></div>
<div class="cemail"><strong><?php _e('E-mail:', 'site5framework') ?></strong> <?php echo of_get_option('sc_contact_email') ?></div>
</div>
<div class="two-third last">
<div id="messages">
<p class="simple-error error" <?php if($hasError != '') echo 'style="display:block;"'; ?>><?php _e('There was an error submitting the form.', 'site5framework'); ?></p>
<p class="simple-success thanks"><?php _e('<strong>Thanks!</strong> Your email was successfully sent. We should be in touch soon.', 'site5framework'); ?></p>
</div>
<form id="contactForm" method="POST">
<div class="one-third">
<label for="nameinput"><?php _e("Your name", "site5framework"); ?></label>
<input type="text" id="nameinput" name="contactName" value="<?php if(isset($_POST['contactName'])) echo $_POST['contactName'];?>" class="requiredField"/>
<span class="error" <?php if($nameError != '') echo 'style="display:block;"'; ?>><?php _e("You forgot to enter your name.", "site5framework");?></span>
</div>
<div class="one-third last">
<label for="emailinput"><?php _e("Your email", "site5framework"); ?></label>
<input type="text" id="emailinput" name="email" value="<?php if(isset($_POST['email'])) echo $_POST['email'];?>" class="requiredField email"/>
<span class="error" <?php if($emailError != '') echo 'style="display:block;"'; ?>><?php _e("You forgot to enter your email address.", "site5framework");?></span>
</div>
<div class="two-third">
<label for="nameinput"><?php _e("Area/Rep", "site5framework"); ?></label>
<select>
<option>Area 1 - Engela</option>
<option>Area 2 - Francois</option>
<option>Area 3 - Johan</option>
</select>
</div>
<div class="two-third">
<label for="Mymessage"><?php _e("Your message", "site5framework"); ?></label>
<textarea cols="20" rows="20" id="Mymessage" name="comments" class="requiredField"><?php if(isset($_POST['comments'])) { if(function_exists('stripslashes')) { echo stripslashes($_POST['comments']); } else { echo $_POST['comments']; } } ?></textarea>
<span class="error" <?php if($commentError != '') echo 'style="display:block;"'; ?>><?php _e("You forgot to enter your comments.", "site5framework");?></span>
</div>
<br class="clear" />
<input type="hidden" name="submitted" id="submitted" value="true" />
<button type="submit" id="submitbutton" class="button small round orange"><?php _e(' SEND MESSAGE ', 'site5framework'); ?></button>
</form>
</div>
<?php endwhile; ?>
</article>
<?php else : ?>
<article id="post-not-found">
<header>
<h1><?php _e("Not Found", "site5framework"); ?></h1>
</header>
<section class="post_content">
<p><?php _e("Sorry, but the requested resource was not found on this site.", "site5framework"); ?></p>
</section>
<footer>
</footer>
</article>
<?php endif; ?>
</div>
</div> <!-- end content -->
<?php get_footer(); ?>

Answer 1

use another contact template!
contact templates are a very vulnerable point in web sites, this one is really insecure (I guess / hope it's quite old).
A few points for the curious (only a first glance, there may be more issues)
the $name parameter is not escaped, malicious user can enter for example bcc addresses, which would be added to the header section, here
the regex for the $email parameter allows %, thus it is possible to enter url_encoded signs like < >
$comments is not secured, too..

Answer 2

Why exactly do you have the need to let users send email with aribtrary name and email address? Are you trying to be an open proxy?
P.S. Lines like this won't do what you probably intended, because they don't handle the case of no parameter or an array being passed.
trim($_POST['contactName']) === ''