3

Today my sendmail service started sending e-mail to various addresses.

/var/spool/mail:

From [email protected]  Fri Jan 30 22:15:30 2015
Return-Path: <[email protected]>
Received: from localhost (localhost)
    by noxcommunity.com (8.13.8/8.13.8) id t0ULFUje031918;
    Fri, 30 Jan 2015 22:15:30 +0100
Date: Fri, 30 Jan 2015 22:15:30 +0100
From: Mail Delivery Subsystem <[email protected]>
Message-Id: <[email protected]>
To: [email protected]
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
    boundary="t0ULFUje031918.1422652530/noxcommunity.com"
Subject: Postmaster notify: see transcript for details
Auto-Submitted: auto-generated (postmaster-notification)

This is a MIME-encapsulated message

--t0ULFUje031918.1422652530/noxcommunity.com

The original message was received at Fri, 30 Jan 2015 22:15:30 +0100
from localhost.localdomain [127.0.0.1]
with id t0ULFUje031916

   ----- The following addresses had permanent fatal errors -----
<s@s>
    (reason: 550 Host unknown)

   ----- Transcript of session follows -----
550 5.1.2 <s@s>... Host unknown (Name server: s: host not found)
550 5.1.1 <[email protected]>... User unknown

--t0ULFUje031918.1422652530/noxcommunity.com
Content-Type: message/delivery-status

Reporting-MTA: dns; noxcommunity.com
Received-From-MTA: DNS; localhost.localdomain
Arrival-Date: Fri, 30 Jan 2015 22:15:30 +0100

Final-Recipient: RFC822; s@s
Action: failed
Status: 5.1.2
Remote-MTA: DNS; s
Diagnostic-Code: SMTP; 550 Host unknown
Last-Attempt-Date: Fri, 30 Jan 2015 22:15:30 +0100

--t0ULFUje031918.1422652530/noxcommunity.com
Content-Type: message/rfc822

Return-Path: <[email protected]>
Received: from noxcommunity.com (localhost.localdomain [127.0.0.1])
    by noxcommunity.com (8.13.8/8.13.8) with ESMTP id t0ULFUje031916
    for <s@s>; Fri, 30 Jan 2015 22:15:30 +0100
Received: (from root@localhost)
    by noxcommunity.com (8.13.8/8.13.8/Submit) id t0ULFUNT031915;
    Fri, 30 Jan 2015 22:15:30 +0100
Date: Fri, 30 Jan 2015 22:15:30 +0100
Message-Id: <[email protected]>
To: s@s
Subject: Facebook
X-PHP-Originating-Script: 0:eb.php
From: "[email protected]" <[email protected]>
Content-Type: text/html

<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 10pt;
font-family:Tahoma
}
--></style>
</head>
<body class='hmmessage'>
<meta http-equiv="Content-Type" content="text/html; charset=unicode">
<meta name="Generator" content="Microsoft SafeHTML"><title>Message body</title><bgsound src="http://email_open_log_pic.php?mid=424e194G221be96cG696b3afG2f&amp;s=a"></bgsound><table width="98%" border="0" cellspacing="0" cellpadding="40"><tbody><tr><td bgcolor="#f7f7f7" width="100%" style="font-family:'lucida grande', tahoma, verdana, arial, sans-serif"><table cellpadding="0" cellspacing="0" border="0" width="620"><tbody><tr><td style="background:#3b5998;color:#FFFFFF;font-weight:bold;font-family:'lucida grande', tahoma, verdana, arial, sans-serif;padding:4px 8px;vertical-align:middle;font-size:16px;letter-spacing:-0.03em;text-align:left"><a style="color:#FFFFFF;text-decoration:none" href="http://goo.gl/QdWtIJ" target="_blank"><span style="color:#FFFFFF">facebook</span></a></td><td style="background:#3b5998;color:#FFFFFF;font-weight:bold;font-family:'lucida grande', tahoma, verdana, arial, sans-serif;padding:4px 8px;vertical-align:middle;font-size:11px;text-align:right"></td></tr><tr><td colspan="2" style="background-color:#FFFFFF;border-bottom:1px solid #3b5998;border-left:1px solid #CCCCCC;border-right:1px solid #CCCCCC;font-family:'lucida grande', tahoma, verdana, arial, sans-serif;padding:15px" valign="top"><table width="100%"><tbody><tr><td width="470px" style="font-size:12px" valign="top" align="left"><div style="margin-bottom:15px;font-size:12px"></div><div style="margin-bottom:15px"><span style="color:#111111;font-size:14px;font-weight:bold;">A friend tagged you in a photo</span></div><div style="margin-bottom:15px"><div style="border-bottom:1px solid #ccc;line-height:5px">&nbsp;</div><br><table cellspacing="0" cellpadding="0" style="border-collapse:collapse"><tbody><tr><td style="padding:5px"></td></tr><tr><td width="150" style="font-size:11px;font-family:'lucida grande', tahoma, verdana, arial, sans-serif;padding:0px 5px 10px 0px"><table cellspacing="0" cellpadding="0" style="border-collapse:collapse"><tbody><tr><td valign="top" style="padding-right:5px"><a href="http://goo.gl/QdWtIJ" style="col!
 or:#3b59
98;text-decoration:none" target="_blank"><img style="border:0px none" alt="Chris Thomas" src="https://fbstatic-a.akamaihd.net/rsrc.php/v2/yo/r/UlIqmHJn-SK.gif" width="50" height="50"></a></td><td valign="top"><span style="font-size:11px;color:#999;padding:0px 0px 10px 0px"><span style="font-size:11px;color:#3B5998;font-weight:bold"><a href="http://goo.gl/QdWtIJ" style="color:#3B5998;text-decoration:none;font-size:11px" target="_blank">Chris Thomas</a></span><br></span></td></tr></tbody></table></td></tr></tbody></table><div style="border-bottom:1px solid #ccc;line-height:5px">&nbsp;</div><br></div><div style="margin-bottom:15px">Thanks,<br>
The Facebook Team</div></td><td valign="top" width="150" style="padding-left:15px" align="left"><table cellspacing="0" cellpadding="0" style="border-collapse:collapse"><tbody><tr><td style="padding:10px;background-color:#fff9d7;border-left:1px solid #e2c822;border-right:1px solid #e2c822;border-top:1px solid #e2c822;border-bottom:1px solid #e2c822"><div style="margin-bottom:15px;font-size:12px"></div><table cellspacing="0" cellpadding="0" style="border-collapse:collapse"><tbody><tr><td style="border-width:1px;border-style:solid;border-color:#3b6e22 #3b6e22 #2c5115;background-color:#69a74e"><table cellspacing="0" cellpadding="0" style="border-collapse:collapse"><tbody><tr><td style="font-size:11px;font-family:'lucida grande', tahoma, verdana, arial, sans-serif;padding:4px 10px 5px;border-top:1px solid #95bf82"><a href="http://goo.gl/QdWtIJ" style="color:#fff;text-decoration:none;font-weight:bold;font-size:13px" target="_blank">View photo</a></td></tr></tbody></table></td></tr></tbody></table></td></tr></tbody></table></td></tr></tbody></table><br><table cellspacing="0" cellpadding="0" style="border-collapse:collapse;width:100%"><tbody><tr><td style="padding:10px;background-color:#fff9d7;border-left:1px solid #e2c822;border-right:1px solid #e2c822;border-top:1px solid #e2c822;border-bottom:1px solid #e2c822"><div style="font-weight:bold;margin-bottom:2px;font-size:11px">To view this friend profile photo, go to:</div><a href="http://goo.gl/QdWtIJ" style="color:#3b5998;text-decoration:none;font-size:11px" target="_blank">http://www.facebook.com/n/?reqs.php&amp;mid=424e194G221be96cG696b3afG2f&amp;bcode=M6l2wBWw&amp;[email protected]</a></td></tr></tbody></table><span style=""><img src="http://www.facebook.com/email_open_log_pic.php?mid=424e194G221be96cG696b3afG2f" style="border:0;width:1px;height:1px"><bgsound src="http://www.facebook.com/email_open_log_pic.php?mid=424e194G221be96cG696b3afG2f&amp;s=a"></bgsound></span></td></tr><tr><td colspan="2" style="color:#999999;padding:10px;font-size:12p!
 x;font-f
amily:'lucida grande', tahoma, verdana, arial, sans-serif">If you don't want to receive these emails from Facebook in the future, please follow the link below to unsubscribe.
http://www.facebook.com/o.php?k=7042bb&amp;u=572254572&amp;mid=424e194G221be96cG696b3afG2f
Facebook, Inc. P.O. Box 10005, Palo Alto, CA 94303</td></tr></tbody></table></td></tr></tbody></table>                    </body>
</html>

maillog:

Jan 30 22:15:30 vm2745 sendmail[31911]: t0ULFTv1031911: [email protected], delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=35539, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (t0ULFTVJ031912 Message accepted for delivery)
Jan 30 22:15:30 vm2745 sendmail[31915]: t0ULFUNT031915: [email protected], size=5525, class=0, nrcpts=1, msgid=<[email protected]>, relay=root@localhost
Jan 30 22:15:30 vm2745 sendmail[31916]: t0ULFUje031916: from=<[email protected]>, size=5760, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Jan 30 22:15:30 vm2745 sendmail[31915]: t0ULFUNT031915: to=s@s, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=35525, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (t0ULFUje031916 Message accepted for delivery)
Jan 30 22:15:30 vm2745 sendmail[31918]: t0ULFUje031916: to=<s@s>, delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=125760, relay=s, dsn=5.1.2, stat=Host unknown (Name server: s: host not found)
Jan 30 22:15:30 vm2745 sendmail[31918]: t0ULFUje031916: to=<[email protected]>, delay=00:00:00, mailer=local, pri=125760, dsn=5.1.1, stat=User unknown
Jan 30 22:15:30 vm2745 sendmail[31918]: t0ULFUje031916: t0ULFUje031918: postmaster notify: User unknown
Jan 30 22:15:30 vm2745 sendmail[31914]: STARTTLS=client, relay=gmail-smtp-in.l.google.com., version=TLSv1/SSLv3, verify=FAIL, cipher=RC4-SHA, bits=128/128
Jan 30 22:15:30 vm2745 sendmail[31918]: t0ULFUje031918: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=36970, dsn=2.0.0, stat=Sent
Jan 30 22:15:30 vm2745 sendmail[31919]: t0ULFUFv031919: [email protected], size=5525, class=0, nrcpts=1, msgid=<[email protected]>, relay=root@localhost
Jan 30 22:15:30 vm2745 sendmail[31914]: t0ULFTVJ031912: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=esmtp, pri=125774, relay=gmail-smtp-in.l.google.com. [74.125.136.26], dsn=5.0.0, stat=Service unavailable
Jan 30 22:15:30 vm2745 sendmail[31914]: t0ULFTVJ031912: to=<[email protected]>, delay=00:00:00, mailer=local, pri=125774, dsn=5.1.1, stat=User unknown
Jan 30 22:15:30 vm2745 sendmail[31914]: t0ULFTVJ031912: t0ULFUVJ031914: postmaster notify: User unknown
Jan 30 22:15:30 vm2745 sendmail[31910]: STARTTLS=client, relay=mta5.am0.yahoodns.net., version=TLSv1/SSLv3, verify=FAIL, cipher=RC4-SHA, bits=128/128
Jan 30 22:15:30 vm2745 sendmail[31921]: t0ULFUrk031921: from=<[email protected]>, size=5760, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Jan 30 22:15:31 vm2745 sendmail[31914]: t0ULFUVJ031914: to=root, delay=00:00:01, xdelay=00:00:00, mailer=local, pri=36998, dsn=2.0.0, stat=Sent
Jan 30 22:15:31 vm2745 sendmail[31919]: t0ULFUFv031919: to=s@s, delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=35525, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (t0ULFUrk031921 Message accepted for delivery)
Jan 30 22:15:31 vm2745 sendmail[31924]: t0ULFUrk031921: to=<s@s>, delay=00:00:01, xdelay=00:00:00, mailer=esmtp, pri=125760, relay=s, dsn=5.1.2, stat=Host unknown (Name server: s: host not found)
Jan 30 22:15:31 vm2745 sendmail[31924]: t0ULFUrk031921: to=<[email protected]>, delay=00:00:01, mailer=local, pri=125760, dsn=5.1.1, stat=User unknown
Jan 30 22:15:31 vm2745 sendmail[31924]: t0ULFUrk031921: t0ULFVrk031924: postmaster notify: User unknown
Jan 30 22:15:31 vm2745 sendmail[31924]: t0ULFVrk031924: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=36970, dsn=2.0.0, stat=Sent
Jan 30 22:15:33 vm2745 sendmail[31910]: t0ULFT2n031908: to=<[email protected]>, delay=00:00:04, xdelay=00:00:04, mailer=esmtp, pri=125778, relay=mta5.am0.yahoodns.net. [98.138.112.38], dsn=5.0.0, stat=Service unavailable
Jan 30 22:15:33 vm2745 sendmail[31910]: t0ULFT2n031908: to=<[email protected]>, delay=00:00:04, mailer=local, pri=125778, dsn=5.1.1, stat=User unknown
Jan 30 22:15:33 vm2745 sendmail[31910]: t0ULFT2n031908: t0ULFX2n031910: postmaster notify: User unknown
Jan 30 22:15:33 vm2745 sendmail[31910]: t0ULFX2n031910: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=37006, dsn=2.0.0, stat=Sent

And similar e-mails go on almost every second.

I am totally baffled about this, what's causing it?

2
  • 3
    First thing first, somehow immediately stop that sendmail instance from talking to the Internet and don't allow it to initiate outbound connections again until you have figured out what is going on and have good reason to believe you have fixed the problem. Go into the server room and physically unplug the network cable if you have to. Every second sendmail is running and spewing garbage across the Internet only increases the probability that you'll end up on blocklists, which will mean a lot more frustration than even a few hours of SMTP downtime and outgoing email delays.
    – user
    Jan 31, 2015 at 14:33
  • 1
    Yeah, I've disabled it the moment I discovered it.
    – IS4
    Jan 31, 2015 at 15:06

1 Answer 1

3

It appears that your server has been hacked, possibly through a web server running PHP software. The sendmail header contains the following incriminating line:

X-PHP-Originating-Script: 0:eb.php

indicating that the email is generated using a PHP script with filename eb.php. The 0 indicates that the script is executed by root user, which could mean that a cron job is being performed to start the script every minute.

The content of the email is a spoof of Facebook notification:

facebook spoof

If you hover your mouse over the link, it would show a shortened URL hosted by Google that would likely redirect anyone who receive an email from your server to a site hosting malware or phishing for your Facebook login detail.

Update:

Since the hacker has already gained root access to your server, deleting the script even if you manage to find it would not help much because:

  1. a backdoor could have already been installed for the hacker come back and undo your recovery effort
  2. processes could be altered to thwart your effort to hunt down malicious scripts that are created and destroyed on the fly
  3. there is no way to be sure that your server is 100% disinfected

What you should do is to reinstall the server to the latest version and restore content from the last good backup. You can find more information on how to deal with a compromised server here.

4
  • 2
    I've located the file in /tmp/.fb/eb.php, deleted everything there, also cleared sendmail queue, but when I started sendmail again, it continued sending mails! The file is still reported as eb.php, but I can't find it now.
    – IS4
    Jan 31, 2015 at 18:23
  • @IllidanS4 Might there be some process that still has the file open? lsof should help.
    – user
    Jan 31, 2015 at 19:23
  • lsof | grep eb.php doesn't show anything.
    – IS4
    Jan 31, 2015 at 19:39
  • @IllidanS4, I have updated my answer stating the possible cause and providing you with a general advice. It is likely to be a rabbit hole going down there :) Feb 1, 2015 at 3:33

Not the answer you're looking for? Browse other questions tagged .