Re: Securing an Email script


"shimmyshack" <matt.farey@xxxxxxxxx> wrote in message
news:1193519779.915072.181330@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Oct 27, 8:27 pm, "Sanders Kaufman" <bu...@xxxxxxxxxxx> wrote:
"Bill H" <some...@xxxxxxxxxxxxxx> wrote in message

news:VradnVdP25-dFL7anZ2dnUVZ_rCtnZ2d@xxxxxxxxxxxxxx

I've changed our web site to use a simple PHP script to send a demo
request to our sales office. We use Postfix and everything is set up
properly and works fine. I've been informed there are some security
issues to review.

Since you do ZERO checking on the values it's nothing BUT security
issues.
You should never pass user-submitted data to mail or data bases without
validating it.



The script looks like:

<html>
<head><title>PHP Mail Sender</title></head>
<body>
<?php

/* Pre-defined script variables. */
/* $eol = "\r\n"; */
$eol = "\n";
$mailto = 'sa...@xxxxxxxxxxxx';
$mailfrom = 'webser...@xxxxxxxxxxxx';
$subject = 'Company Demo Request';

/* Initialize a clean array to replace $_POST with clean data */
$name = $_POST['name'];
$title = $_POST['name'];
$company = $_POST['name'];
$email = $_POST['name'];
$phone = $_POST['name'];
$message = $_POST['name'];

/* Build HTML $salesmessage variable to pass to mail script */
$salesmessage = "<HTML><HEAD></HEAD><BODY>" . $eol;
$salesmessage .= "The following information comes from the company
web
site<BR>".$eol;
$salesmessage .= "demonstration link.<BR><BR>".$eol;
$salesmessage .= "<TABLE cols='2'>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Company Name:
</TD><TD>". $company ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Name:
</TD><TD>". $name ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Title:
</TD><TD>". $title ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Email:
</TD><TD>". $email ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Phone:
</TD><TD>". $phone ."</TD></TR>".$eol;
$salesmessage .= "</TABLE><BR>" . $eol;
$salesmessage .= $message . $eol;
$salesmessage .= "</BODY></HTML>" . $eol;

/* To send HTML mail, the Content-type header must be set */
$headers = 'MIME-Version: 1.0' . $eol;
$headers .= 'Content-type: text/html; charset=iso-8859-1' . $eol;

/* Additional header information */
$headers .= 'To: Sales <' . $mailto . '>' . $eol;
$headers .= 'From: ' . 'AsiWeb <' . $mailfrom . '>' . $eol . $eol;

/* PHP form validation: the script checks that the Email field contains
a
valid email address
and the Subject field isn't empty. preg_match performs a regular
expression match. It's a
very powerful PHP function to validate form fields and other
strings -
see PHP manual for
details. */
if ($email == "") {
echo "<script>alert('Invalid or missing email
address')</script>";
echo "<script>history.back(1)</script>";
} elseif ($name == "") {
echo "<script>alert('Invalid or missing name')</script>";
echo "<script>history.back(1)</script>";
} elseif ($company == "") {
echo "<script>alert('Invalid or missing company')</script>";
echo "<script>history.back(1)</script>";

/* Sends the mail and outputs the "Thank you" string if the mail is
successfully sent, or the
error string otherwise. */
} elseif (mail($mailto, $subject, $salesmessage, $headers)) {
echo "<script>";
echo "self.location='../demo_response.html';";
echo "</script>";
} else {
echo "<script>alert('Cannot send email to $mailto')</script>";
echo "<script>history.back(1)</script>";
}
?>
</body>
</html>

The main issue I'm wondering about is if I control the to and from
address
and header information for the mail, as I do above, is it possible to
inject something else into the email to hijack the mail server?

Thanks,

Bill

On Oct 27, 8:27 pm, "Sanders Kaufman" <bu...@xxxxxxxxxxx> wrote:
"Bill H" <some...@xxxxxxxxxxxxxx> wrote in message

news:VradnVdP25-dFL7anZ2dnUVZ_rCtnZ2d@xxxxxxxxxxxxxx

I've changed our web site to use a simple PHP script to send a demo
request to our sales office. We use Postfix and everything is set up
properly and works fine. I've been informed there are some security
issues to review.

Since you do ZERO checking on the values it's nothing BUT security
issues.
You should never pass user-submitted data to mail or data bases without
validating it.



The script looks like:

<html>
<head><title>PHP Mail Sender</title></head>
<body>
<?php

/* Pre-defined script variables. */
/* $eol = "\r\n"; */
$eol = "\n";
$mailto = 'sa...@xxxxxxxxxxxx';
$mailfrom = 'webser...@xxxxxxxxxxxx';
$subject = 'Company Demo Request';

/* Initialize a clean array to replace $_POST with clean data */
$name = $_POST['name'];
$title = $_POST['name'];
$company = $_POST['name'];
$email = $_POST['name'];
$phone = $_POST['name'];
$message = $_POST['name'];

/* Build HTML $salesmessage variable to pass to mail script */
$salesmessage = "<HTML><HEAD></HEAD><BODY>" . $eol;
$salesmessage .= "The following information comes from the company
web
site<BR>".$eol;
$salesmessage .= "demonstration link.<BR><BR>".$eol;
$salesmessage .= "<TABLE cols='2'>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Company Name:
</TD><TD>". $company ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Name:
</TD><TD>". $name ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Title:
</TD><TD>". $title ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Email:
</TD><TD>". $email ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Phone:
</TD><TD>". $phone ."</TD></TR>".$eol;
$salesmessage .= "</TABLE><BR>" . $eol;
$salesmessage .= $message . $eol;
$salesmessage .= "</BODY></HTML>" . $eol;

/* To send HTML mail, the Content-type header must be set */
$headers = 'MIME-Version: 1.0' . $eol;
$headers .= 'Content-type: text/html; charset=iso-8859-1' . $eol;

/* Additional header information */
$headers .= 'To: Sales <' . $mailto . '>' . $eol;
$headers .= 'From: ' . 'AsiWeb <' . $mailfrom . '>' . $eol . $eol;

/* PHP form validation: the script checks that the Email field contains
a
valid email address
and the Subject field isn't empty. preg_match performs a regular
expression match. It's a
very powerful PHP function to validate form fields and other
strings -
see PHP manual for
details. */
if ($email == "") {
echo "<script>alert('Invalid or missing email
address')</script>";
echo "<script>history.back(1)</script>";
} elseif ($name == "") {
echo "<script>alert('Invalid or missing name')</script>";
echo "<script>history.back(1)</script>";
} elseif ($company == "") {
echo "<script>alert('Invalid or missing company')</script>";
echo "<script>history.back(1)</script>";

/* Sends the mail and outputs the "Thank you" string if the mail is
successfully sent, or the
error string otherwise. */
} elseif (mail($mailto, $subject, $salesmessage, $headers)) {
echo "<script>";
echo "self.location='../demo_response.html';";
echo "</script>";
} else {
echo "<script>alert('Cannot send email to $mailto')</script>";
echo "<script>history.back(1)</script>";
}
?>
</body>
</html>

The main issue I'm wondering about is if I control the to and from
address
and header information for the mail, as I do above, is it possible to
inject something else into the email to hijack the mail server?

Thanks,

Bill

On Oct 27, 7:52 pm, "Bill H" <some...@xxxxxxxxxxxxxx> wrote:
I've changed our web site to use a simple PHP script to send a demo
request
to our sales office. We use Postfix and everything is set up properly
and
works fine. I've been informed there are some security issues to review.

The script looks like:

<html>
<head><title>PHP Mail Sender</title></head>
<body>
<?php

/* Pre-defined script variables. */
/* $eol = "\r\n"; */
$eol = "\n";
$mailto = 'sa...@xxxxxxxxxxxx';
$mailfrom = 'webser...@xxxxxxxxxxxx';
$subject = 'Company Demo Request';

/* Initialize a clean array to replace $_POST with clean data */
$name = $_POST['name'];
$title = $_POST['name'];
$company = $_POST['name'];
$email = $_POST['name'];
$phone = $_POST['name'];
$message = $_POST['name'];

/* Build HTML $salesmessage variable to pass to mail script */
$salesmessage = "<HTML><HEAD></HEAD><BODY>" . $eol;
$salesmessage .= "The following information comes from the company web
site<BR>".$eol;
$salesmessage .= "demonstration link.<BR><BR>".$eol;
$salesmessage .= "<TABLE cols='2'>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Company Name:
</TD><TD>".
$company ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Name:
</TD><TD>".
$name ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Title:
</TD><TD>".
$title ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Email:
</TD><TD>".
$email ."</TD></TR>".$eol;
$salesmessage .= "<TR><TD style='color:blue'>Contact Phone:
</TD><TD>".
$phone ."</TD></TR>".$eol;
$salesmessage .= "</TABLE><BR>" . $eol;
$salesmessage .= $message . $eol;
$salesmessage .= "</BODY></HTML>" . $eol;

/* To send HTML mail, the Content-type header must be set */
$headers = 'MIME-Version: 1.0' . $eol;
$headers .= 'Content-type: text/html; charset=iso-8859-1' . $eol;

/* Additional header information */
$headers .= 'To: Sales <' . $mailto . '>' . $eol;
$headers .= 'From: ' . 'AsiWeb <' . $mailfrom . '>' . $eol . $eol;

/* PHP form validation: the script checks that the Email field contains a
valid email address
and the Subject field isn't empty. preg_match performs a regular
expression match. It's a
very powerful PHP function to validate form fields and other strings -
see PHP manual for
details. */
if ($email == "") {
echo "<script>alert('Invalid or missing email address')</script>";
echo "<script>history.back(1)</script>";
} elseif ($name == "") {
echo "<script>alert('Invalid or missing name')</script>";
echo "<script>history.back(1)</script>";
} elseif ($company == "") {
echo "<script>alert('Invalid or missing company')</script>";
echo "<script>history.back(1)</script>";

/* Sends the mail and outputs the "Thank you" string if the mail is
successfully sent, or the
error string otherwise. */
} elseif (mail($mailto, $subject, $salesmessage, $headers)) {
echo "<script>";
echo "self.location='../demo_response.html';";
echo "</script>";
} else {
echo "<script>alert('Cannot send email to $mailto')</script>";
echo "<script>history.back(1)</script>";
}
?>
</body>
</html>

The main issue I'm wondering about is if I control the to and from
address
and header information for the mail, as I do above, is it possible to
inject
something else into the email to hijack the mail server?

Thanks,

Bill

even a 10second glance reveals a few issues
cross site scripting.
header injection may be possible
use of \n\n rather than \r\n

im not sure where your "powerful validate occurs" but its not in this
script as you make no attempt to use regular expressions.

ROFLMAO !!!

so, 'powerful validation' is eq. to regex?!!!

you are, on all other counts, correct however. :^)

Oh and in case youre wondering - why would I perform regular
expression validation on a mailto address I control - this is a demo
right, how will you ask the user to put in a valid email address, or
any other data. You will of course have to use some kind of
validation.

My recommendation is to use a prewritten class to send emails - check
out Zend, or some other framework for some (more) secure scripts,
rolling your own should only be done when you think you can improve on
the work of others with years of experience - often learned the hard
way! The last thing you want is to have your email server blacklisted.

zend email classes are faaaar too bloated to send such simple emails. i've
got a script (posted last week) that i've been using for years. it's about
30-ish lines. does anything i want it to.

if you use a secure class you script will look something like

$email->setTo( $mailto );
$email->setFrom( $mailto );
$email->setMsg( $mailto );
if( !$email->send() )
{
echo 'it wasnt sent';
}
else
{
echo 'it was';
}

why would you need an instance of a email object? a static class with a send
method taking params would do nicely if you wanted to go that
route...otherwise, a stand-alone function works just great. thinking you
need classes when you don't is less than productive at times.

the prevention of injection occurs elsewhere, but do not repeat your
mistake of echoing back to the screen what the user has input unless
you use htmlentities or some other filtering on the input.

Or else a user can use this to take control of your webpages, this is
the XSS I was talking about. This is pretty much rule number 1 of
server side coding with forms, since you go on to send emails, I think
perhaps you should check out WASC webpages to see the complexity of
decent secure dynamic pages before you get into hot water.

complexity is !== security. simplicity most assuredly *is*.


.

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