Re: Re: Possible hacker using php script to send e-mails?

Hello Manuel, this seems to be the right track. However I do not have linebrakes in there, but the message gets passed by POST. This is my script error.php: <?php ############################################################### # requieres $hostpath= '../'; require $hostpath . 'global/server.inc'; require $hostpath. 'global/class.phpmailer.php'; ############################################################### ############################################################### # set vars $from = $_POST[from]; $errormsg = $_POST[errormsg]; $message = $_POST[message]; ############################################################### ##################################################################### # send e-mail $mail = new phpmailer; $mail->IsHTML(false); $mail->From = $mailadress_webmaster; $mail->FromName = $email_from_name_2; $mail->AddAddress($mailadress_webmaster); $mail->AddReplyTo($from); $mail->Subject = 'Fehlerbericht';

$mail->Body    = $message.'

Fehler: '.$errormsg.' Absender: '.$from; $mail->Send(); HEADER("Location:/about/index.php?fa=3&msg=4"); ##################################################################### ?> The e-mails I have received contain two subject lines?! Have a look: Subject: Fehlerbericht Date: Sat, 11 Mar 2006 01:37:33 +0100 From: My Server <webmaster@> Reply-To: my email Content-Type: multipart/alternative; boundary=6cf6796619a040f4ad26b61683f77eac MIME-Version: 1.0 Subject: little boat undulating near the shore, and Message-Id: <20060311003733.6666BC027F8@myserver.com> This is a multi-part message in MIME format. --6cf6796619a040f4ad26b61683f77eac Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit from those who stood around the young girl alone stood silent and immovable her thoughts seemed to be far away. et some people fancied they saw how she --6cf6796619a040f4ad26b61683f77eac-- . Message-ID: <6d5cf83331c3317c86b2f7df61b92aa2@*.myserver.com> X-Priority: 3 X-Mailer: PHPMailer [version 1.72] MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="iso-8859-1" Fehler: Absender: s Content-Type: multipart/alternative; boundary=6cf6796619a040f4ad26b61683f77eac MIME-Version: 1.0 Subject: little boat undulating near the shore, and bcc: frekiforbes@aol.com This is a multi-part message in MIME format. --6cf6796619a040f4ad26b61683f77eac Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit from those who stood around the young girl alone stood silent and immovable her thoughts seemed to be far away. et some people fancied they saw how she --6cf6796619a040f4ad26b61683f77eac-- . Any ideas? Regards, Merlin Manuel Lemos schrieb:

Hello, on 03/11/2006 04:12 PM Rasmus Lerdorf said the following:

I am running php 4.x on a suse 9.x machine. There is a php script which resides on a webapp that is responsible for sending e-mail to myself in case of errors like db-errors or similar. Called error.php This script does include phpmailer and uses it to send the e-mails to me. Now I am receiving on the e-mail specified as TO: e-mails with different subject than specified and different text?! All english text with wired sentences, must be a bot or so. How is this possible? The subject line is fixed and right after that commend send is executed. So no idea how they do it and how I can prevent it. It looks like this: $mail->Subject = 'Fehlerbericht'; $mail->Send(); How is it possible that they change this subject line? I checked the server log and each time an e-mail has been sent to me of that kind there is a logentry in apache log that says that this script has been executed. So the e-mails definatelly come from that script?!

If you are setting message headers with untrusted values that may contain line breaks, that is your problem. Line breaks make mail systems interpret the next line as a new header. That header may be used to inject new recipients for instance using Bcc: . You can have line breaks in header but you need to escape them properly so they are interpreted as continuation lines rather than new headers.

That is only true for the additional_headers (4th) argument to the mail function. That argument is specifically for doing free-form headers, so as long as you only use the to, subject and message arguments to the mail function you are safe.

That is what I said, sending headers with untrusted values, so people have to use the 4th argument to set for instance the From: header. This From: header is often set to values set in forms to the e-mail address and name of the person that is trying to contact the site people. That is usually from where most the PHP mail form abuses come from. As I said line breaks in the From: or other headers are not invalid. Actually line breaks should be used to comply with RFC recommendations and do not exceed the 78/998 line length limit. When these limits are exceeded, messages may arrive corrupted. The mail function is a better than nothing solution. It can still be used but to send RFC compliant messages, often it is necessary to correctly format message contents. That is why I always recommend this or other class that takes care of those (many) details: http://www.phpclasses.org/mimemessage