Trace email spamming in Plesk using php scripts

Remote Linux Server Administrator
Server Management Service

Are you trying to trace email spamming in Plesk?

This guide will help you.

Just recently, one of our Customer contacted us regarding mail spamming attacks on his Plesk hosted Server. He could not figure out and trace the spam issue.

Thousands of email was sent with bounce-back messages.

However, there is no such email server.

Generally, If your hosting offerings include mail services, keep in mind that your mail server can be used for malicious purposes, such as sending spam.

Outgoing spam can cause an increased load on the server and complaints from recipients.

What's more important, your server IP addresses might be added to public black lists, such as Spamhaus or OpenBL lists.

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to perform Plesk related tasks.

In this context, we shall look into how to trace email spamming in Plesk using PHP scripts.

How to find the source of spam in Plesk ?

Before we proceed with the steps to find mail spamming from PHP scripts, let us see the steps in order to find mail spamming in qmail (Plesk).

This includes the steps to find spamming from PHP scripts in the Plesk server also.

1. Initially, we check the mail count in the qmail queue:

# /var/qmail/bin/qmail-qstat
messages in queue: 27303
messages in queue but not yet preprocessed: 100

2. In addition, to see the inbox of mails:

/var/qmail/mailnames/

3.Then to find the user that sends most of the mails (if the emails are sent without using PHP scripts):

# cat /var/log/maillog |grep -I smtp_auth |grep -I user |awk ‘{print $11}’ |sort |uniq -c |sort -n

4. In order to read message headers:

# /var/qmail/bin/qmail-qread
22 Sep 2012 15:03:07 CDT #2996948 9073 bouncing
done remote user1@domain1.com
done remote user2@domain2.com
done remote user3@domain3.com

From the above result, we can see the sender and recipients of messages.

If the message has too many recipients, then it is mostly SPAM.

5. To view this message using its ID #2996948:

# find /var/qmail/queue/mess/ -name 2996948

6. Finally, we check the result, starting after 'Received' to see its origin :

a) Received: (qmail 19514 invoked by uid 1009); 21 Oct 2007 17:48:22 +0700

This means that mail was sent via some CGI script by user UID 1009.

Then, find a corresponding domain for this UID:

# grep 1009 /etc/passwd

Now we can find the cgi script and deny it’s working.

b) Received: (qmail 19622 invoked from network); 21 Oct 2007 17:52:36 +0700

Received: from external_domain.com (10.0.0.1)

If we get the above header, then the message was accepted for delivery via SMTP and the sender is an authorized mail user.

c) Received: (qmail 19514 invoked by uid 48); 21 Oct 2007 17:48:22 +0700

If the uid is 48, then spam is sent using some PHP scripts. (48 – UID of apache user).

How to Trace email spamming in Plesk using PHP scripts ?

The script below shows currently running php scripts in the server:

# lsof +r 1 -p `ps axww | grep httpd | grep -v grep | awk ‘ { if(!str) { str=$1 } else
str=str”,”$1}END{print str}’` | grep vhosts | grep php

To find the exact location of php script, follow the below method:

1) Create /var/qmail/bin/sendmail-wrapper script:

#!/bin/sh
(echo X-Additional-Header: $PWD ;cat) | tee -a /var/tmp/mail.send|
/var/qmail/bin/sendmail-qmail “$@”

2) Then we run:

# touch /var/tmp/mail.send
# chmod a+rw /var/tmp/mail.send
# chmod a+x /var/qmail/bin/sendmail-wrapper
# mv /var/qmail/bin/sendmail /var/qmail/bin/sendmail-qmail
# ln -s /var/qmail/bin/sendmail-wrapper /var/qmail/bin/sendmail

3) Eventually, revert it:

# rm -f /var/qmail/bin/sendmail
# ln -s /var/qmail/bin/sendmail-qmail /var/qmail/bin/sendmail
/var/tmp/mail.send will contain lines starting with ‘X-Additional’
# grep X-Additional /var/tmp/mail.send | grep `cat /etc/psa/psa.conf | grep
HTTPD_VHOSTS_D | sed -e ‘s/HTTPD_VHOSTS_D//’

These will give the directories from where the mail script is running.

If the queue is high and corrupt, we can recreate the qmail queue in Plesk:

/etc/init.d/qmail stop
/etc/init.d/xinetd stop
mv /var/qmail/queue /var/qmail/queue_old
rpm -Uvh –force psa-qmail-1.03-rh7.3.build030207.16

This will recreate the Qmail queue structure:

/etc/init.d/qmail start
/etc/init.d/xinetd start