Posts Tagged ‘scanner’

Tools to scan a Linux / Unix Web server for Malware and Rootkits / Lynis and ISPProtect – clean Joomla / WordPress and other CMS for malware and malicious scripts and trojan codes

Monday, March 14th, 2016


If you have been hacked or have been suspicious that someone has broken up in some of the shared web hosting servers you happent o manage you already probably have tried the server with rkhuter, chroot and unhide tools which gives a general guidance where a server has been compromised

However with the evolution of hacking tools out there and the boom of Web security XSS / CSS / Database injections and PHP scripts vulnerability catching an intruder especially spammers has been becoming more and more hard to achieve.

Just lately a mail server of mine's load avarage increased about 10 times, and the CPU's and HDD I/O load jump over the sky.
I started evaluating the situation to find out what exactly went wrong with the machine, starting with a hardware analysis tools and a physical check up whether all was fine with the hardware Disks / Ram etc. just to find out the machine's hardware was working perfect.
I've also thoroughfully investigated on Logs of Apache, MySQL, TinyProxy and Tor server and bind DNS and DJBDns  which were happily living there for quite some time but didn't found anything strange.

Not on a last place I investigated TOP processes (with top command) and iostat  and realized the CPU high burst lays in exessive Input / Output of Hard Drive. Checking the Qmail Mail server logs and the queue with qmail-qstat was a real surprise for me as on the queue there were about 9800 emails hanging unsent, most of which were obviously a spam, so I realized someone was heavily spamming through the server and started more thoroughfully investigating ending up to a WordPress Blog temp folder (writtable by all system users) which was existing under a Joomla directory infrastructure, so I guess someone got hacked through the Joomla and uploaded the malicious php spammer script to the WordPress blog. I've instantly stopped and first chmod 000 to stop being execuded and after examing deleted view73.php, javascript92.php and index8239.php which were full of PHP values with binary encoded values and one was full of encoded strings which after being decoding were actually the recepient's spammed emails.
BTW, the view*.php javascript*.php and index*.php files were owned by www-data (the user with which Apache was owned), so obviously someone got hacked through some vulnerable joomla or wordpress script (as joomla there was quite obscure version 1.5 – where currently Joomla is at version branch 3.5), hence my guess is the spamming script was uploaded through Joomla XSS vulnerability).

As I was unsure wheteher the scripts were not also mirrored under other subdirectories of Joomla or WP Blog I had to scan further to check whether there are no other scripts infected with malware or trojan spammer codes, webshells, rootkits etc.
And after some investigation, I've actually caught the 3 scripts being mirrored under other webside folders with other numbering on filename view34.php javascript72.php, index8123.php  etc..

I've used 2 tools to scan and catch malware the trojan scripts and make sure no common rootkit is installed on the server.

1. Lynis (to check for rootkits)
2. ISPProtect (Proprietary but superb Website malware scanner with a free trial)

1. Lynis – Universal security auditing tool and rootkit scanner

Lynis is actually the well known rkhunter, I've used earlier to check servers BSD and Linux servers for rootkits.
To have up-to-date version of Lynis, I've installed it from source:

cd /tmp
tar xvfz lynis-2.1.1.tar.gz
mv lynis /usr/local/
ln -s /usr/local/lynis/lynis /usr/local/bin/lynis


Then to scan the server for rootkits, first I had to update its malware definition database with:

lynis update info

Then to actually scan the system:

lynis audit system

Plenty of things will be scanned but you will be asked on a multiple times whether you would like to conduct different kind fo system services and log files, loadable kernel module rootkits and  common places to check for installed rootkits or server placed backdoors. That's pretty annoying as you will have to press Enter on a multiple times.


Once scan is over you will get a System Scan Summary like in below screenshot:


Lynis suggests also a very good things that might be tampered to make the system more secure, so using some of its output when I have time I'll work out on hardening all servers.

To prevent further incidents and keep an eye on servers I've deployed Lynis scan via cron job once a month on all servers, I've placed under a root cronjob on every first dae of month in following command:



server:~# crontab -u root -e
0 3 1 * * /usr/local/bin/lynis –quick 2>&1 | mail -s "lynis output of my server"


2. ISPProtect – Website malware scanner

ISPProtect is a malware scanner for web servers, I've used it to scan all installed  CMS systems like WordPress, Joomla, Drupal etc.
ISPProtect is great for PHP / Pyhon / Perl and other CMS based frameworks.
ISPProtect contains 3 scanning engines: a signature based malware scanner, a heuristic malware scanner, and a scanner to show the installation directories of outdated CMS systems.
Unfortunately it is not free software, but I personally used the FREE TRIAL option  which can be used without registration to test it or clean an infected system.
I first webserver first locally for the infected site and then globally for all the other shared hosting websites.

As I wanted to check also rest of hosted websites, I've run ISPProtect over the all bunch of installed websites.
Pre-requirement of ISPProtect is to have a working PHP Cli and Clamav Anti-Virus installed on the server thus on RHEL (RPM) based servers make sure you have it installed if not:

server:~# yum -y install php

server:~# yum -y install clamav

Debian based Linux servers web hosting  admins that doesn't have php-cli installed should run:

server:~# apt-get install php5-cli

server:~# apt-get install clamav

Installing ISPProtect from source is with:

mkdir -p /usr/local/ispprotect
chown -R root:root /usr/local/ispprotect
chmod -R 750 /usr/local/ispprotect
cd /usr/local/ispprotect
tar xzf ispp_scan.tar.gz
rm -f ispp_scan.tar.gz
ln -s /usr/local/ispprotect/ispp_scan /usr/local/bin/ispp_scan


To initiate scan with ISPProtect just invoke it:

server:~# /usr/local/bin/ispp_scan



I've used it as a trial

Please enter scan key:  trial
Please enter path to scan: /var/www

You will be shown the scan progress, be patient because on a multiple shared hosting servers with few hundred of websites.
The tool will take really, really long so you might need to leave it for 1 hr or even more depending on how many source files / CSS / Javascript etc. needs to be scanned.

Once scan is completed scan and infections found logs will be stored under /usr/local/ispprotect, under separate files for different Website Engines and CMSes:

After the scan is completed, you will find the results also in the following files:

Malware => /usr/local/ispprotect/found_malware_20161401174626.txt
Wordpress => /usr/local/ispprotect/software_wordpress_20161401174626.txt
Joomla => /usr/local/ispprotect/software_joomla_20161401174626.txt
Drupal => /usr/local/ispprotect/software_drupal_20161401174626.txt
Mediawiki => /usr/local/ispprotect/software_mediawiki_20161401174626.txt
Contao => /usr/local/ispprotect/software_contao_20161401174626.txt
Magentocommerce => /usr/local/ispprotect/software_magentocommerce_20161401174626.txt
Woltlab Burning Board => /usr/local/ispprotect/software_woltlab_burning_board_20161401174626.txt
Cms Made Simple => /usr/local/ispprotect/software_cms_made_simple_20161401174626.txt
Phpmyadmin => /usr/local/ispprotect/software_phpmyadmin_20161401174626.txt
Typo3 => /usr/local/ispprotect/software_typo3_20161401174626.txt
Roundcube => /usr/local/ispprotect/software_roundcube_20161401174626.txt

ISPProtect is really good in results is definitely the best malicious scripts / trojan / trojan / webshell / backdoor / spammer (hacking) scripts tool available so if your company could afford it you better buy a license and settle a periodic cron job scan of all your servers, like lets say:


server:~# crontab -u root -e
0 3  1 * *   /usr/local/ispprotect/ispp_scan –update && /usr/local/ispprotect/ispp_scan –path=/var/www – –non-interactive –scan-key=AAA-BBB-CCC-DDD

Unfortunately ispprotect is quite expensive so I guess most small and middle sized shared hosting companies will be unable to afford it.
But even for a one time run this tools worths the try and will save you an hours if not days of system investigations.
I'll be glad to hear from readers if aware of any available free software alternatives to ISPProtect. The only one I am aware is Linux Malware Detect (LMD).
I've used LMD in the past but as of time of writting this article it doesn't seems working any more so I guess the tool is currently unsupported / obsolete.


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Fix X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied – Finally a working solution and what causes the error

Wednesday, July 22nd, 2015


I've lost a whole day and was angry and irritated after moving (migrating) a Working Qmail installation in a binary form from a Debian Lenny 5.0 to a Debian 7.0 Wheezy Linux. The whole migration exercise was quite of a crazy move and I can tell you it didn't worth the effort as I lost much more time than even if I went on installing the server following Thibs Great Qmail Tutorial.

Yes I know many would say why do you still bother with an old and unsupported Qmail Mail server and not go with Postfix, the logic is correct however the whole issue is the previous installation has a number of domains already running VirtualMail hosting using VPopMail, so migrating all the old mailboxes from Qmail to Postfix are not worthy IMHO. Plus I honestly love qmail for being so stable even today (even without support). After all most of Qmail is secure enough already 🙂
And to be honest I don't so much care about security as in the old days as I know NSA, does already have access to any server on planet 🙂

Almost always when a Qmail migration happens I end up swearing and sweating and generally getting crazy, but anyways …

The overall migration of binaries went quite OK I just copied every binary and all the related libraries from the old Debian 5.0 to Debian 7.0 and installed the following long list of perl deb binaries using apt-get:



I've also installed with apt-get daemontools and daemontools-run ucspi and some others to get all the necessery binaries qmail needs the whole list of apt installed packages is here

I've also copied all the old binaries from /usr/local/lib from server1 to server2, some others from /usr/local/share and /usr/share as well as /usr/lib/courier /usr/lib/courier-authlib /usr/local/libexec /usr/local/sbin also had to link a couple of libraries such as /usr/lib/libcrypto* , link  /usr/lib/ to /usr/lib/ and copy /usr/lib/ and few others which i don't exactly remember.

Well anyways once I've copied everything Qmail looked fined except I had a couple of permission issues and had to clean up and fix the queue with qfixq, I've also used qmail-scanner*/contrib/ script to test whether qmail-scanner was running fine, e.g.:

./ -doit

As well as




script, thanks to which I've captured and resolved few of permission problems 

Finally I've stuck upon this shitty errors (appearing) in /var/log/syslog and /var/log/messages



Jul 21 22:04:19 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:08:27 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:08:38 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:11:17 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:16:09 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:19:15 vps186637 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:38:59 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:42:33 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:43:49 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:46:05 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:50:40 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied
Jul 21 22:53:08 ns2 X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied




There is plenty of things written about this: X-Qmail-Scanner-2.08st:[] cannot create /var/spool/qscan/tmp – Permission denied

But all written is too obscure and too old already somewhere between 2004 and 2010, I've been digging through Gentoo Forums, Fedora Debian and other Linux installs and everyone used to be pointing a permission issue with /var/spool/qscan/ said theoretically to be causing the error, however all looked perfectly fine with my /var/spool/qscan , e.g.:



roo@ns2:/usr/local/src# ls -ld /var/spool/qscan/
drwxr-s— 6 qscand qscand 4096 Jul 21 23:07 /var/spool/qscan/





ls -al /var/spool/qscan/
total 244904
drwxr-s— 6 qscand qscand      4096 Jul 21 23:07 .
drwxr-xr-x 4 root   root        4096 Jul 20 21:17 ..
drwxrwx— 5 qscand qscand      4096 Oct 12  2011 archives
-rwxr-x— 1 qscand qscand      1434 Oct 12  2011
-rw——- 1 qscand qscand 249731919 Jul 21 23:11 qmail-queue.log
-rw——- 1 qscand qscand    398225 Oct 28  2011 qmail-queue.log.1
-rw-rw—- 1 root   qscand        74 Jul 21 23:07 qmail-scanner-queue-version.txt
lrwxrwxrwx 1 root   qscand        16 Jul 21 23:07 qscan -> /var/spool/qscan
drwxrwx— 5 qscand qscand      4096 Oct 12  2011 quarantine
-rw-r—– 1 root   qscand     12288 Jul 21 23:07 quarantine-events.db
-rw-r—– 1 qscand qscand     10443 Oct 12  2011 quarantine-events.txt
-rw-rw—- 1 qscand qscand    580033 Jul 21 23:07 quarantine.log
-rw-r—– 1 qscand qscand      2739 Oct 12  2011 settings_per_domain.txt
drwxr-x— 3 qscand qscand      4096 Jul 21 23:11 tmp
drwxrwx— 5 qscand qscand      4096 Oct 12  2011 working


Some suggested that /var/spool/qscan should be owned by qscand:clamav instead so I tried this but it didn't help,
others recommended adding clamav groupid into qscand's but this didn't help either:

root@ns2:/usr/local/src# grep -i clamav /etc/group


Besides that I was getting also this shitty error:


Jul 21 20:05:42 vps186637 X-Qmail-Scanner-2.08st:[ns2143750194279012466] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 20:06:51 vps186637 X-Qmail-Scanner-2.08st:[ns2143750201179013125] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 20:15:42 vps186637 X-Qmail-Scanner-2.08st:[ns214375025407906015] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 20:16:06 vps186637 X-Qmail-Scanner-2.08st:[ns2143750256579011980] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 20:18:54 vps186637 X-Qmail-Scanner-2.08st:[ns2143750273479014847] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 20:21:03 vps186637 X-Qmail-Scanner-2.08st:[ns2143750286379028491] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status -1/72057594037927935
Jul 21 22:07:47 vps186637 X-Qmail-Scanner-2.08st:[ns2143750926779010097] clamdscan: corrupt or unknown clamd scanner error or memory/resource/perms problem – exit status 512/2


All the time in logs, so I thought something might be wrong with clamdscan and followed and tried some suggestions from as described here, however none of the fixes described there worked for me …

I also tried to reinstall clamav from source using a bit of modified version of this tutorial

This didn't help either … I saw some suggestions online that the permission issues are caused by some wrong clamd.conf and freshclamd.conf configuration options – failing clamdscan, but this didn't work either. I also tried to remove clamdscan and substitute it with clamscan  as a suggested workaround but this didn't work either …

I spend about 6 hours trying to catch what is causing this issues so finally I went on and re-installed bigger part of Qmail using Thibs tutorial over the old installation.

I've also tried in mean time multiple time to rebuild qmail scanner database with:

setuidgid qscand /var/qmail/bin/ -g

Played around with permissions in /etc/clamav e.g.



chown -R qscand:clamav /var/log/clamav /var/lib/clamav /var/run/clamav
chown qscand:qscand /etc/clamav/freshclam.conf





/etc/cron.daily/qmail-scanner with following content


cat /etc/cron.daily/qmail-scanner
setuidgid qscand /var/qmail/bin/ -z

However in /var/log/qmail/qmail-smtpd/current and /var/log/qmail-send/current I continously got:

Qmail 451 qq temporary problem (#4.3.0) error

Interestingly during looking for a solution to the 451 qq temporary problem and:

status: qmail-todo stop processing asap / status: exiting – I've stumbled to my own blog post here 🙂


Finally, I tried to reinstall qmail-scanner and in mean time update it to  Version: 2.11 – st – patch – 20130319
Just to realized something was wrong with suidperl, e.g. in Debian 7.0.* Wheezy perl-suid binary is no longer in repositories so only way to have suidperl there is either to re-compile perl from source manually which is too much work and I think in most cases not worthy the effort or to use a small suid-wrapper:

#include <unistd.h>
#include <errno.h>

main( int argc, char ** argv, char ** envp )
              if( setgid(getegid()) ) perror( "setgid" );
              if( setuid(geteuid()) ) perror( "setuid" );
              envp = 0; /* blocks IFS attack on non-bash shells */
              system( "/usr/bin/perl", argv, envp );
              perror( argv[0] );
              return errno;


Create it into a file lets say suid-wrapperc and compile the file with GNU C Compiler:

$ gcc -o suid-wrapper suid-wrapper.c

Then move the suid-wrapper produced binary into /usr/bin/suidperl e.g.



$ mv suid-wrapper /usr/bin/suidperl

Last you will need to edit /var/qmail/bin/





# vim /var/qmail/bin/

And substitute





#!/usr/bin/perl -T





Note!!! that permissions should be suid and owned by qscand:qscand as follows:





ls -al /var/qmail/bin/
-rwsr-sr-x 1 qscand qscand 159727 Jul 21 23:11 /var/qmail/bin/

Finally to resolve the error I had to restart qmail via qmailctl start / stop script:





root@ns2:/var/qmail/bin# qmailctl restart
Restarting qmail:
* Stopping qmail-smtpdssl.
* Stopping qmail-smtpd.
* Sending qmail-send SIGTERM and restarting.
* Restarting qmail-smtpd.
* Restarting qmail-smtpdssl.


Finally to test emails are sent and receiver properly I used good old mail command part of bsd-mailx deb package


# mail -s "testing 12345678"



I've also tested with plain telnet to verify no errors because often the mail command doesn't return (show) errors on email sent and errors are written only in /var/log/mail.log or /var/log/qmail/* logs



# telnet localhost 25
Connected to localhost.
Escape character is '^]'.
220 servername.localdomain.tld ESMTP
mail from: <>
250 ok
rcpt to: <>
250 ok
354 go ahead
From: Test_sender <>
To: Test_receiver <>
Subject: Just a stupid SMTP test


Just a test !
250 ok 1279384489 qp 3711
221 servername.localdomain.tld
Connection closed by foreign host.

One other thing which probably helped I did was:

# qmailctl doqueue


Thanks God this time, it worked out without any QQ errors 🙂 !


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Maldetect – Malware web content file scanner for GNU / Linux – Keep your hosting servers Malware clean

Tuesday, June 4th, 2013

Linux malware detect scan for malware from commandline / Fedora, CentOS, Debian, Ubuntu 

It is so common nowadays that Shared hosting clients upload PHP / Javascript / Ajax scripts carelessly downloaded from somewhere containing malicious features or infected by third party script kiddie tools which replicate themselves after succesfully exploit some common PHP or Perl vulnerability. I'm sure even as time of writing this post probably millions of old un-updated Hosting Linux servers are silent Malware hives.
Therefore For Shared Hosting server servers it is useful to know about the existence of Maldetect – Linux Malware scanner also known under the name LMD.

Linux Maldetect – in what it does is very similar to Windows good Spyware Detect and Clean tool Malware Bytes. LMD uses Spyware definition database collected from network edge Intrusion detection systems who caught Web bugs commonly exploited as well as from custom user submissions of Malicious stuff. Maldetect's database can easily be exported and plays well together with ClamAV antivirus. LMD is very precious and is one of the must have outfits for hosting admins, as its use allows you to determine succesful cracking before system is rootkited and you have to audit for Backdoors or Rookit with rkhunter and chkroot

1. Install Linux MalDetect

LMD is young project so it does not still have a package deb and rpm package builds. Installation is done from source;

debian:~# wget
debian:~# tar -xzf maldetect-current.tar.gz
debian:~# cd maldetect-*
debian:~# ./

Linux Malware Detect v1.4.1
            (C) 2002-2013, R-fx Networks <>
            (C) 2013, Ryan MacDonald <>
inotifywait (C) 2007, Rohan McGovern <>
This program may be freely redistributed under the terms of the GNU GPL

installation completed to /usr/local/maldetect
config file: /usr/local/maldetect/conf.maldet
exec file: /usr/local/maldetect/maldet
exec link: /usr/local/sbin/maldet
exec link: /usr/local/sbin/lmd
cron.daily: /etc/cron.daily/maldet

maldet(3143): {sigup} performing signature update check…
maldet(3143): {sigup} local signature set is version 201205035915
maldet(3143): {sigup} new signature set (2013060217799) available
maldet(3143): {sigup} downloaded
maldet(3143): {sigup} downloaded
maldet(3143): {sigup} downloaded
maldet(3143): {sigup} downloaded
maldet(3143): {sigup} downloaded
maldet(3143): {sigup} signature set update completed
maldet(3143): {sigup} 11509 signatures (9641 MD5 / 1868 HEX)

2. Maldetect configs and binaries

Config is default installed in –  /usr/local/maldetect/conf.maldet
Main executed binary is placed in –  /usr/local/maldetect/maldet
There is a cron skele file placed in /etc/cron.daily/maldet. Its useful to run maldet via cron to check all sites on server and get e-mail reports.

3. Keep maldet up2date

debian:~# maldet --update-ver

Linux Malware Detect v1.4.2
            (C) 2002-2013, R-fx Networks <>
            (C) 2013, Ryan MacDonald <>
inotifywait (C) 2007, Rohan McGovern <>
This program may be freely redistributed under the terms of the GNU GPL v2

maldet(3511): {update} checking for available updates...
maldet(3511): {update} hashing install files and checking against server...
maldet(3511): {update} latest version already installed.

4. Update Maldetect definitions manually

Maldetect Malware definitions are designed to auto-update via cron. For people who don't like to waste CPU time and scrape on HDD with cronjob;

debian:~# maldet --update

5. Configure LMD

Tune according to your needs in config (/usr/local/maldetect/conf.maldet)

email_subj="Attention Malware found! Check your server!"

6. Scanning for Malware manually

debian:~# maldet -a /home,/var/www/blog,/sbin,/opt
Linux Malware Detect v1.4.2
(C) 2002-2013, R-fx Networks <>
(C) 2013, Ryan MacDonald <>
inotifywait (C) 2007, Rohan McGovern <>
This program may be freely redistributed under the terms of the GNU GPL v2

maldet(21709): {scan} signatures loaded: 11509 (9641 MD5 / 1868 HEX)
maldet(21709): {scan} building file list for /var/www/blog, this might take awhile...
maldet(21709): {scan} file list completed, found 6814 files...
maldet(21709): {scan} found ClamAV clamscan binary, using as scanner engine...
maldet(21709): {scan} scan of /var/www/blog (6814 files) in progress...

maldet(21709): {scan} scan completed on /var/www/blog: files 6814, malware hits 0, cleaned hits 0
maldet(21709): {scan} scan report saved, to view run: maldet --report 062813-1012.21709

As you see from above output  you can view Maldet report by issuing:

debian:~# maldet --report 062813-1012.21709

malware detect scan report for pcfreak:

SCAN ID: 070113-1223.7481

TIME: Jul  1 12:24:20 +0300





NOTE: quarantine is disabled! set quar_hits=1 in conf.maldet or to quarantine results run:

debian:~# maldet -q 070113-1223.7481


{CAV}Exploit.SafariCrash-1 : ./osX/dos/1715.html

{CAV}Exploit.PPC : ./osX/local/

{CAV}Exploit.Perl.Sadmin : ./solaris/remote/

{CAV}Exploit.FirefoxCrash : ./multiple/dos/1716.html

{HEX}exp.linux.setuid.13 : ./multiple/local/

{CAV}HTML.Shellcode : ./multiple/remote/2082.html


In case some badware is captured by Maldet to quarantine files run suggested command:

debian:~# maldet -q 070113-1223.7481

Linux Malware Detect v1.4.2

            (C) 2002-2013, R-fx Networks <>

            (C) 2013, Ryan MacDonald <>

inotifywait (C) 2007, Rohan McGovern <>

This program may be freely redistributed under the terms of the GNU GPL v2


maldet(21341): {quar} malware quarantined from './php/remote/2008.php' to '/usr/local/maldetect/quarantine/2008.php.19608'

maldet(21341): {clean} restoring /usr/local/maldetect/quarantine/2008.php.19608 for cleaning attempt

maldet(21341): {clean} trying to clean ./php/remote/2008.php with base64.inject.unclassed rule

maldet(21341): {clean} rescanning ./php/remote/2008.php for malware hits

maldet(21341): {clean} clean successful on ./php/remote/2008.php


Just for a close up below is a list of common 60 Malwares found on Hosting servers (taken from Maldetect Website);

base64.inject.unclassed     perl.ircbot.xscan
bin.dccserv.irsexxy         perl.mailer.yellsoft
bin.ircbot.php3             php.cmdshell.c100
bin.ircbot.unclassed        php.cmdshell.c99
bin.pktflood.ABC123         php.cmdshell.cih
bin.pktflood.osf            php.cmdshell.egyspider
bin.trojan.linuxsmalli      php.cmdshell.fx29
c.ircbot.tsunami            php.cmdshell.ItsmYarD
exp.linux.rstb              php.cmdshell.Ketemu
exp.linux.unclassed         php.cmdshell.N3tshell
exp.setuid0.unclassed       php.cmdshell.r57
gzbase64.inject             php.cmdshell.unclassed
html.phishing.auc61         php.defash.buno          php.exe.globals
perl.connback.DataCha0s     php.include.remote
perl.connback.N2            php.ircbot.InsideTeam
perl.cpanel.cpwrap          php.ircbot.lolwut
perl.ircbot.atrixteam       php.ircbot.sniper
perl.ircbot.bRuNo           php.ircbot.vj_denie
perl.ircbot.Clx             php.mailer.10hack
perl.ircbot.devil           php.mailer.bombam
perl.ircbot.fx29            php.mailer.PostMan
perl.ircbot.magnum          php.phishing.AliKay
perl.ircbot.oldwolf         php.phishing.mrbrain
perl.ircbot.putr4XtReme     php.phishing.ReZulT
perl.ircbot.rafflesia       php.pktflood.oey


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How to scan for DHCP available servers in a Network range on Linux and FreeBSD

Thursday, December 8th, 2011

GNU / Linux and FreeBSD had a nifty little program (tool) called dhcping . dhcpingsend a DHCP request to DHCP server to see if it’s up and running. dhcping is also able to send a request to DHCP servers on a whole network range and therefore it can e asily be used as a scanner to find any available DHCP servers in a network.
This makes dhcping a nmap like scanner capable to determine if dhcp servers are in a network 😉
To scan an an entire network range with dhclient and find any existing DHCP servers:

noah:~# dhcping -s -r -v
Got answer from:
received from, expected from
no answer

In above’s output actually my Dlink wireless router returns answer to the broadcast DHCP LEASE UDP network requests of dhcping .
On a networks where there is no DHCP server available, the requests dhcping -s -r -v returns:

noah:~# dhcping -s -r -v
no answer

This article was inspired by a post, I’ve red by a friend (Amridikon), so thx goes to him.


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Cause and solution for Qmail sent error “Requested action aborted: error in processing Server replied: 451 qq temporary problem (#4.3.0)”

Friday, October 28th, 2011

One of the qmail servers I manage today has started returning strange errors in Squirrel webmail and via POP3/IMAP connections with Thunderbird.

What was rather strange is if the email doesn’t contain a link to a webpage or and attachment, e.g. mail consists of just plain text the mail was sent properly, if not however it failed to sent with an error message of:

Requested action aborted: error in processing Server replied: 451 qq temporary problem (#4.3.0)

After looking up in the logs and some quick search in Google, I come across some online threads reporting that the whole issues are caused by malfunction of the (script checking mail for viruses).

After a close examination on what is happening I found out /usr/sbin/clamd was not running at all?!
Then I remembered a bit earlier I applied some updates on the server with apt-get update && apt-get upgrade , some of the packages which were updated were exactly clamav-daemon and clamav-freshclam .
Hence, the reason for the error:

451 qq temporary problem (#4.3.0)

was pretty obvious which is using the clamd daemon to check incoming and outgoing mail for viruses failed to respond, so any mail which contained any content which needed to go through clamd for a check and returned back to did not make it and therefore qmail returned the weird error message.
Apparently for some reason apparently the earlier update of clamav-daemon failed to properly restart, the init script /etc/init.d/clamav-daemon .

Following fix was very simple all I had to do is launch clamav-daemon again:

linux:~# /etc/inid.d/clamav-daemon restart

Afterwards the error is gone and all mails worked just fine 😉

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Filter messages in Qmail with unwanted words, get rid of the Viagra annoying spam with Qtrap

Sunday, September 4th, 2011

Drop qmail received mail containing banned / unwanted words to get rid of Viagra and Sex related spam

Recently the annoying Viagra spam has emerged again. Therefore I decided to clean up some of the mails received to one of the qmail servers to protect users emailbox from this viagra peril.

To do so I’ve remember about an old script which used to be part of qmail install, the script is called qtrap and is able to filter emails based on list of specific mail contained words.
Since is gone (down) for some time and its still available only on few mirrored locations which by the way are not too easy to find I decided to write a little post on how could be integrated quick & easy with any Qmail + Vpopmail install out there.

Hereby I include the description for given by the script author:

“ script is applied on a per domain basis and serves as a “bad word” scanner to catch any spam that Spamassassin may have missed. This filter serves as the last defense against SPAM before it arrived in your inbox. I like this filter because it helps to get rid of any SPAM that happens to make it by Spamassassin. Without any protection at all, my mailbox gets a shit ton of SPAM every day. Within the first 3 months I enacted the Qtrap filter, Qtrap logged over 9,000 deleted SPAM messages, none of which were legitimate e-mails. My keyboard’s delete key was very appreciated the extra rest.

Any emails that are scanned and contain a banned word will be automatically deleted and logged by the qtrap script. A whitelist feature now exists so that individual addresses or domains can be exempt from the qtrap scan.”

Now as one might have general idea on what the script does. Here is the step by step integration;

1. Create necessery qtrap directory and logs and set proper permissions

If the vpopmail is installed in /home/vpopmail , issue the following commands.

debian:~# cd /home/vpopmail
debian:~# mkdir -p qtrap/logs
debian:/home/vpopmail/qtrap# cd qtrap
debian:/home/vpopmail/qtrap# wget
debian:/home/vpopmail/qtrap# cd ~
debian:~# touch /home/vpopmail/qtrap/logs/qtrap.logdebian:~# chown -R vpopmail:vchkpw /home/vpopmail/qtrapdebian:~# chmod -R 755 /home/vpopmail/qtrap

On older qmail installations it could be vpopmail is installed in /var/vpopmail if that’s the case, link /var/vpopmail to /home/vpopmail and go back to step 1. To link:

debian:~# ln -sf /var/vpopmail/ /home/vpopmail

2. Edit to whitelist email addresses and build a ban words list

a) Include the email addresses mail arriving from which would not be checked by

Inside in line 63, there is a shell function whitelist_check(), the function looks like so:

whitelist_check () {
case $WHITELIST in|
echo $SENDER found in whitelist on `date "+%D %H:%M:%S"` >> /home/vpopmail/qtrap/logs/qtrap.log
exit 0;;

By default the script has just two sample mails which gets whitelisted this is the line reading:|

The whitelisted emails should be separated with a pipe, thus to add two more sample emails to get whitelisted by script the line should be changed like:|||

In order to whitelist an entire domain let’s say add a line to the above code like:||||*

b) Defining the bad words ban list, mails containing them should not be delivery by qmail

The function that does check for the ban word list inside the script is checkall();, below is a paste from the script function:

checkall () {
printout $BANNED_WORDS
echo MESSAGE DROPPED from $SENDER because of $BANNED_WORDS on `date "+%D %H:%M:%S"` >> /home/vpopmail/qtrap/logs/qtrap.log
exit 99;;

checkall(); is located on line 74 in, the exact list of banned words which the script should look for is located on line 76, the default filters only mails containing just 4 words, e.g.:


To add the Viagra and VIAGRA common spam words to the list, modify it and expand like so:


The delimiter is again | , so proceed further and add any unwanted spam words that are not common for any legit mails.

3. Install to process all emails delivered to vpopmail

If its necessery to install the dropping of mails based on word filtering only to a single vpopmail virtualdomain do it with cmd:

debian:~# cd /home/vpopmail/domains/
debian:/home/vpopmail/domains/ touch
debian:/home/vpopmail/domains/ echo '| /home/vpopmail/qtrap/' >>
debian:/home/vpopmail/domains/ echo "| /home/vpopmail/bin/vdelivermail '' bounce-no-mailbox" >>
debian:/home/vpopmail/domains/ chown vpopmail:vchkpw
debian:/home/vpopmail/domains/ cp -rpf .qmail-default .qmail-default.bak; mv .qmail-default
If however needs to get installed for all existing vpopmail virtualdomains on the qmail server, issue a one liner bash script:

debian:~# cd /home/vpopmail/domains
debian:/var/vpopmail/domains# for i in *; do cd $i; echo "| /home/vpopmail/qtrap/" >> $i/;
echo "| /home/vpopmail/bin/vdelivermail '' bounce-no-mailbox" >> $i/;
chown vpopmail:vchkpw; mv .qmail-default .qmail-default.old; mv .qmail-default; cd ..; done

This for loop will add ‘| /home/vpopmail/qtrap/’ to all .qmail-default for all vpopmail domains.

Afterwards the .qmail-default file should contain the following two lines:

| /home/vpopmail/qtrap/
| /home/vpopmail/bin/vdelivermail '' delete

A very important thing here you should consider that adding some common words, as let’s say hello or mail etc. could easily drop almost all the emails the qmail hands in to vpopmail.

Caution!! Never ever implement common words in the list of words !!
Always make sure the banned words added to are words that are never enter an everyday legit email.

Another thing to keep in mind is that doesn’t make a copy of the received message ,though it can easily be modified to complete this task.
Any mail that matches the banned words list will be dropped and lost forever.

4. Check if is working

To check, if qtrap is working send mail to some mailbox located on the qmail server containing inside subject or mail message body the unwanted word defined inside

The mail should not be received in the mailbox to which its sent, if qtrap is working moreover should log it inside it’s log file:

debian:~# cat /home/vpopmail/qtrap/logs/qtrap.log
MESSAGE DROPPED from because of viagra on 09/03/11 11:34:19
MESSAGE DROPPED from because of Viagra on 09/03/11 11:39:29

If the qtrap.log contains records similar to the one above, and the mail matching the banned word is not delivered, is properly configured. If any issues check in qmail logs, they should have a good pointer on what went wrong with invokation.

Note that I’ve integrated to custom qmail install running on Debian Lenny 5.0 GNU/Linux.
If I have time I’ll soon test if its working fine on the latest stable Debian Squeeze and will report here in comments.
If however someone is willing to test if the script works on Debian Squeeze 6.0 or have tested it already please drop a comment to report if it works fine., is a bit oldish and is not written to work too optimal therefore on some heavy loaded mail servers it can create some extra load and a bit delay the mail delivery. Thus when implementang one needs to consider the downsides of putting it in.

Also I was thinking tt might be nice if the script is rewritten to read the ban words and whitelist mails from files instead of as it is now as the words are hard coded in the script.
If I have some free time, I’ll probably do this, though I’m not sure if this is a too good idea as this might have a negative performance impact on the script execution time, as each instance of the script invoked should do one more operation of reading a file storing the ban words.

Well that’s pretty much it, enjoy 😉

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Scanning shared hosting servers to catch abusers, unwanted files, phishers, spammers and script kiddies with clamav

Friday, August 12th, 2011

Clamav scanning shared hosting servers to catch abusers, phishers, spammers, script kiddies etc.  logo

I’m responsible for some GNU/Linux servers which are shared hosting and therefore contain plenty of user accounts.
Every now and then our company servers gets suspended because of a Phishing websites, Spammers script kiddies and all the kind of abusers one can think of.

To mitigate the impact of the server existing unwanted users activities, I decided to use the Clamav Antivirus – open source virus scanner to look up for potentially dangerous files, stored Viruses, Spammer mailer scripts, kernel exploits etc.

The Hosting servers are running latest CentOS 5.5. Linux and fortunately CentOS is equipped with an RPM pre-packaged latest Clamav release which of the time of writting is ver. (0.97.2).

Installing Clamav on CentOS is a piece of cake and it comes to issuing:

[root@centos:/root]# yum -y install clamav

After the install is completed, I’ve used freshclam to update clamav virus definitions

[root@centos:/root]# freshclam
ClamAV update process started at Fri Aug 12 13:19:32 2011
main.cvd is up to date (version: 53, sigs: 846214, f-level: 53, builder: sven)
WARNING: getfile: daily-13357.cdiff not found on remote server (IP:
WARNING: getpatch: Can't download daily-13357.cdiff from
WARNING: getfile: daily-13357.cdiff not found on remote server (IP:
WARNING: getpatch: Can't download daily-13357.cdiff from
WARNING: getfile: daily-13357.cdiff not found on remote server (IP:
WARNING: getpatch: Can't download daily-13357.cdiff from
WARNING: Incremental update failed, trying to download daily.cvd
Downloading daily.cvd [100%]
daily.cvd updated (version: 13431, sigs: 173670, f-level: 60, builder: arnaud)
Downloading bytecode.cvd [100%]
bytecode.cvd updated (version: 144, sigs: 41, f-level: 60, builder: edwin)
Database updated (1019925 signatures) from (IP:

In my case the shared hosting hosted websites and FTP user files are stored in /home directory thus I further used clamscan in the following way to check report and log into file the scan results for our company hosted user content.

[root@centos:/root]# screen clamscan -r -i --heuristic-scan-precedence=yes --phishing-scan-urls=yes --phishing-cloak=yes --phishing-ssl=yes --scan-archive=no /home/ -l /var/log/clamscan.log
home/user1/mail/new/,S=14295: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/,S=14260: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/,S=22663: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/new/,S=13114: Heuristics.Phishing.Email.SpoofedDomain FOUND/home/user1/mail/,S=8283:2,S: Heuristics.Phishing.Email.SSL-Spoof FOUND/home/user1/mail/,S=6935:2,S: Heuristics.Phishing.Email.SSL-Spoof FOUND

I prefer running the clamscan in a screen session, because it’s handier, if for example my ssh connection dies the screen session will preserve the clamscan cmd execution and I can attach later on to see how scan went.

clamscan of course is slower as it does not use Clamav antivirus daemon clamd , however I prefer running it without running the daemon, as having a permanently running clamd on the servers sometimes creates problems or hangs and it’s not really worthy to have it running since I’m intending to do a clamscan no more than once per month to see some potential users which might need to be suspended.

Also later on, after it finishes all possible problems are logged to /var/log/clamscan.log , so I can read the file report any time.

A good idea might also be to implement the above clamscan to be conducted, once per month via a cron job, though I’m still in doubt if it’s better to run it manually once per month to search for the malicious users content or it’s better to run it via cron schedule.

One possible pitfall with automating the above clamscan /home virus check up, might be the increased load it puts to the system. In some cases the Webserver and SQL server might be under a heavy load at the exactly same time the clamscan cron work is running, this might possible create severe issues for users websites, if it’s not monitored.
Thus I would probably go with running above clamscan manually each month and monitor the server performance.
However for people, who have “iron” system hardware and clamscan file scan is less likely to cause any issues, probably a cronjob would be fine. Here is sample cron job to run clamscan:

10 05 01 * * clamscan -r -i --heuristic-scan-precedence=yes --phishing-scan-urls=yes --phishing-cloak=yes --phishing-ssl=yes --scan-archive=no /home/ -l /var/log/clamscan.log >/dev/null 2>&1

I’m interested to hear if somebody already is using a clamscan to run on cron without issues, once I’m sure that running it on cron would not lead to server down-times, i’ll implement it via cron job.

Anyone having experience with running clamscan directory scan through crond? 🙂

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How to suspend Cpanel user through ssh / Cpanel shell command to suspend users

Friday, August 5th, 2011

One of the servers running Cpanel has been suspended today and the Data Center decided to completely bring down our server and gave us access to it only through rescue mode running linux livecd.

Thus I had no way to access the Cpanel web interface to suspend the “hacker” who by the way was running a number of instances of this old Romanian script kiddies brute force ssh scanner called sshscan .

Thanksfully Cpanel is equipped with a number of handy scripts for emergency situations in /scripts directory. These shell management scripts are awesome for situations like this one, where no web access is not avaiable.

To suspend the abuser / (abusive user ) I had to issue the command:

root@rescue [/]# /scripts/suspendacct abuse_user
Changing Shell to /bin/false...chsh: Unknown user context is not authorized to change the shell of abuse_user
Locking Password...Locking password for user abuse_user.
passwd: Success
Suspending mysql users
warn [suspendmysqlusers] abuse_user has no databases.
Notification => via EMAIL [level => 3]
Account previously suspended (password was locked).
/bin/df: `/proc/sys/fs/binfmt_misc': No such file or directory
Using Universal Quota Support (quota=0)
Suspended document root /home/abuse_user/public_html
Suspended document root /home/abuse_user/public_html/
Using Universal Quota Support (quota=0)
Updating ftp passwords for abuse_user
Ftp password files updated.
Ftp vhost passwords synced
abuse_user's account has been suspended

That’s all now the user is suspended, so hopefully the DC will bring the server online in few minutes.

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