How to find which script on my server is sending spam emails? [duplicate]

My server is sending the spam email and I am not able to find out which script is sending them.

The emails were all from nobody@myhost so disabled from the cpanel that nobody should not be allowed to send emails

Now at least they are not going out, I keep receiving them. This is mail I get:

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  [email protected]
    Mail sent by user nobody being discarded due to sender restrictions in WHM->Tweak Settings

------ This is a copy of the message, including all the headers. ------

Return-path: <[email protected]>
Received: from nobody by cpanel.myserver.com with local (Exim 4.80)
        (envelope-from <[email protected]>)
        id 1UBBap-0007EM-9r
        for [email protected]; Fri, 01 Mar 2013 08:34:47 +1030
To: [email protected]
Subject: Order Detail
From: "Manager Ethan Finch" <[email protected]>
X-Mailer: Fscfz(ver.2.75)
Reply-To: "Manager Ethan Finch" <[email protected]>
Mime-Version: 1.0
Content-Type: multipart/alternative;boundary="----------1362089087512FD47F4767C"
Message-Id: <[email protected]>
Date: Fri, 01 Mar 2013 08:34:47 +1030

------------1362089087512FD47F4767C
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
Content-Transfer-Encoding: 7bit

This is my logs for exim logs:

2013-03-01 14:36:00 no IP address found for host gw1.corpgw.com (during SMTP connection from [203.197.151.138]:54411)
2013-03-01 14:36:59 H=() [203.197.151.138]:54411 rejected MAIL [email protected]: HELO required before MAIL
2013-03-01 14:37:28 H=(helo) [203.197.151.138]:54411 rejected MAIL [email protected]: Access denied - Invalid HELO name (See RFC2821 4.1.1.1)
2013-03-01 14:37:28 SMTP connection from (helo) [203.197.151.138]:54411 closed by DROP in ACL
2013-03-01 14:37:29 cwd=/var/spool/exim 2 args: /usr/sbin/exim -q
2013-03-01 14:37:29 Start queue run: pid=12155
2013-03-01 14:37:29 1UBBap-0007EM-9r ** [email protected] R=enforce_mail_permissions: Mail sent by user nobody being discarded due to sender restrictions in WHM->Tweak Settings
2013-03-01 14:37:29 cwd=/var/spool/exim 7 args: /usr/sbin/exim -t -oem -oi -f <> -E1UBBap-0007EM-9r
2013-03-01 14:37:30 1UBHFp-0003A7-W3 <= <> R=1UBBap-0007EM-9r U=mailnull P=local S=7826 T="Mail delivery failed: returning message to sender" for [email protected]
2013-03-01 14:37:30 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1UBHFp-0003A7-W3
2013-03-01 14:37:30 1UBBap-0007EM-9r Completed
2013-03-01 14:37:32 1UBHFp-0003A7-W3 aspmx.l.google.com [2607:f8b0:400e:c00::1b] Network is unreachable
2013-03-01 14:37:38 1UBHFp-0003A7-W3 => [email protected] <[email protected]> R=lookuphost T=remote_smtp H=aspmx.l.google.com [74.125.25.26] X=TLSv1:RC4-SHA:128
2013-03-01 14:37:39 1UBHFp-0003A7-W3 Completed
2013-03-01 14:37:39 End queue run: pid=12155
2013-03-01 14:38:20 SMTP connection from [127.0.0.1]:36667 (TCP/IP connection count = 1)
2013-03-01 14:38:21 SMTP connection from localhost [127.0.0.1]:36667 closed by QUIT
2013-03-01 14:42:45 cwd=/ 2 args: /usr/sbin/sendmail -t
2013-03-01 14:42:45 1UBHKv-0003BH-LD <= [email protected] U=root P=local S=1156 T="[cpanel.server.com] Root Login from IP 122.181.3.130" for [email protected]
2013-03-01 14:42:45 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1UBHKv-0003BH-LD
2013-03-01 14:42:47 1UBHKv-0003BH-LD aspmx.l.google.com [2607:f8b0:400e:c00::1a] Network is unreachable
2013-03-01 14:42:51 1UBHKv-0003BH-LD => [email protected] R=lookuphost T=remote_smtp H=aspmx.l.google.com [74.125.25.27] X=TLSv1:RC4-SHA:128
2013-03-01 14:42:51 1UBHKv-0003BH-LD Completed
2013-03-01 14:43:22 SMTP connection from [127.0.0.1]:37499 (TCP/IP connection count = 1)
2013-03-01 14:43:23 SMTP connection from localhost [127.0.0.1]:37499 closed by QUIT

Is there any way to find which script, or which user, is generating those?

Solution 1:

Linux Malware Detect (http://www.rfxn.com/projects/linux-malware-detect/) installation is quite easy :). Go via this link, download http://www.rfxn.com/downloads/maldetect-current.tar.gz. The link to this file is located at the very top of the web-page. Then unzip this archive, go to newly created directory by running cd in your terminal. In the directory run

sudo ./install.sh

which will install the scanner to your system. To perform the scanning itself you are to run

sudo /usr/local/sbin/maldet -a /

-a option here means that you want ro scan all the files. Use -r instead to scan only recent ones. / specifies the directory where scan should be performed. So just change it to any directory you want.

Just that )

Solution 2:

The emails were all from nobody@myhost

Find all processes that is running as nobody:

ps -U nobody

SMTP connection from [127.0.0.1]:36667 (TCP/IP connection count = 1)

Run netstat under watch to see which process is connecting to port 25:

watch 'netstat -na | grep :25'

These steps can help you find out the culprit is the... web server. Then you can run a strace to see which script is called when an email is sent:

strace -f -e trace=open,stat -p 1234 -o wserver.strace

(1234 is the parent PID of the web server process)

Solution 3:

Run a malware scanner, such as maldet, or AVG, or both, on your user's data. Most malicious scripts are picked up by such tools.