Posts tagged Security

Back in the year 1999, long before I started my Asterisk days, I spent most of my time as a security consultant and cyber forensics expert. I remember that in those days, most of the hacks were script kiddies exploiting some Windows IIS well known hole, and you would usually get the “Hacked by Chinese” black display on your website – how annoying!

In any case, I’ve recently replaced my co-location firewall. I’ve migrated from a Linux system running IPtables with a manual script, to a fully blown IPCOP installation. Ok, so IPCOP is nothing more than a fancy GUI for IPtables, but hey, it makes my life a whole lot easier on the management side – and it’s very stable – so who am I to complain?

I’ve decided to run a small experiment, I wanted to setup a Linux box, with a root password of 123456. My question was this, how much time will pass from the moment the machine was up, on a new IP address, till the machine gets hacked – and more importantly, from where and what got installed on the machine?

So, the machine fired up for the first time at Fri Jul 25 23:19, believe it or not, the machine got hacked at Sat Jul 26 00:50. A mere 90 minutes into the air, and the machine got hacked. The funny thing was that at Sat Jul 26 03:09 it got hacked again to the same account, then at Sat Jul 26 03:21, which also closed the root access via SSH at this point. Following below is the last log:

root     pts/0        77.127.137.52    Sat Jul 26 06:04   still logged in
reboot   system boot  2.6.18-53.1.14.e Sat Jul 26 06:02          (00:17)
root     pts/1        92.80.195.126    Sat Jul 26 03:21 - 03:24  (00:03)
root     pts/0        78.110.163.31    Sat Jul 26 03:09 - 05:20  (02:11)
root     pts/1        60.220.240.7     Sat Jul 26 00:50 - 00:50  (00:00)
root     pts/0        77.127.137.52    Fri Jul 25 23:24 - 01:39  (02:14)
root     tty1                          Fri Jul 25 23:22 - 23:24  (00:01)
reboot   system boot  2.6.18-53.1.14.e Fri Jul 25 23:19          (07:00)
root     tty1                          Fri Jul 25 22:14 - down   (01:03)
reboot   system boot  2.6.18-53.1.14.e Fri Jul 25 21:58          (01:19)

I admit it, putting a machine on the open net, with a root password of 123456 and open root access to SSH – that’s kind of a honey pot the size of the grand canyon. But what amazed me here was not the speed, but actually the locations of the hacks: 60.220.240.7, 78.110.163.31 and 92.80.195.126. One hacker is in China, the other in Romania and the third in the UK. What is this? a real hacker? maybe 3 different robots scanning? – I can’t really tell here. However, the traces they left were interesting enough – which lead me to believe we’re talking about robot hacking.

First off, a look at /var/log/audit/audit.log immediately showed the logins – the hacker didn’t even remove the log file – marking of a script kiddie running an automated script. So, what did they leave on my box, let’s take a look. Running ‘netstat -apn | less’ would show me open ports, unless netstat was replaced. However, lets start with this:

tcp        0      0 172.31.31.16:34183          195.47.220.2:6667           ESTABLISHED 2940/crond
tcp        0      1 172.31.31.16:57263          195.54.102.4:6667           SYN_SENT    2940/crond
tcp        0      1 172.31.31.16:46043          195.68.221.221:6667         SYN_SENT    2940/crond

Ok, so this is most probably an IRC bot waiting for instructions from the hacker – till now nothing special. The script tries to masquerade the bot with a legitimate process name: crond. Well, that may fool a beginner Linux Sysadmin, however, seeing crond connecting to 3 other hosts at TCP 6667 – ok, that’s kind’a lame – no?

I wonder where he hid the script? maybe he replaced crond?

root@pbx:~ $ find / -name "crond"
/usr/sbin/crond
/var/tmp/.www/crond
/var/lock/subsys/crond
/etc/sysconfig/crond
/etc/rc.d/init.d/crond
/etc/pam.d/crond
root@pbx:~ $

Hmm… /var/tmp/.www/crond looks promising, let’s see what’s in there:

root@pbx:~ $ ls -la /var/tmp/
total 24
drwxrwxrwt  4 root root 4096 Jul 26  2008 .
drwxr-xr-x 25 root root 4096 Jul 25  2008 ..
drwxr-xr-x  2 root root 4096 Jun 27 17:03 .spd
drwxr-xr-x  4  501  502 4096 Jul 26  2008 .www

Yummy! Let’s check it out:

root@pbx:/var/tmp $ ll .spd/

total 1316

-rwxr-xr-x 1 root root    265 Nov 19  2005 gen-pass.sh

-rwxr-xr-x 1 root root     72 Jun 26 19:43 pass_file

-rwxr-xr-x 1 root root  21407 Nov 19  2005 pscan2

-rwxr-xr-x 1 root root    218 Jun 27 16:59 s

-rwxr-xr-x 1 root root 453972 Nov 19  2005 ss

-rwxr-xr-x 1 root root 842736 Jun 26 19:20 ssh-scan

-rwxr-xr-x 1 root root    312 Jun 27 17:02 x

root@pbx:/var/tmp $ ll .www/

total 888

-rwxr-xr-x 1  501  502    353 Jul 26  2008 1.user

-rwxr-xr-x 1  501  502    349 Jul 26  2008 2.user

-rwxr-xr-x 1  501  502    353 Mar 14  2009 3.user

-rwxr-xr-x 1  501  502    317 Nov  6  2007 autorun

-rw-r--r-- 1 root root      0 Jul 26  2008 belgian.seen

-rwxr-xr-x 1  501  502    942 May 15  2003 checkmech

-rwxr-xr-x 1  501  502  23237 May 15  2003 configure

-rwxr-xr-x 1  501  502 492135 Mar  4  2005 crond

-rwxr-xr-x 1  501  502     48 Jul 26  2008 cron.d

-rwxr-xr-x 1  501  502    171 Jul 26  2008 cutitas

-rwxr-xr-x 1  501  502   4147 May 15  2003 genuser

-rwxr-xr-x 1  501  502    157 Jul 25 17:36 LinkEvents

-rwxr-xr-x 1  501  502      0 Oct 15  2007 lucifer.seen

-rwxr-xr-x 1  501  502   2154 May 15  2003 Makefile

-rwxr-xr-x 1  501  502     14 Jul 26  2008 m.dir

-rwxr-xr-x 1  501  502  22882 May 15  2003 m.help

-rwxr-xr-x 1  501  502    748 May 15  2003 mkindex

-rwxr-xr-x 1  501  502   1043 Jul 26  2008 m.lev

-rwxr-xr-x 1  501  502      5 Jul 25 17:35 m.pid

-rwxr-xr-x 1  501  502   1068 Jul 26  2008 m.ses

-rwxr-xr-x 1  501  502   1675 Mar 25  2009 m.set

-rwxr-xr-x 1  501  502 167964 Mar 16  2001 pico

-rwxr-xr-x 1  501  502  84476 Jun 23  2006 pico.tgz

drwxr-xr-x 2  501  502   4096 Jul 23 15:48 r

-rwxr-xr-x 1  501  502    661 Jul 12 22:00 shadow}{700.seen

-rwxr-xr-x 1  501  502    661 Jul 12 22:00 shadow}{800.seen

-rwxr-xr-x 1  501  502    715 Jul 12 22:00 shadow}{900.seen

drwxr-xr-x 2  501  502   4096 Jul 23 15:51 src

-rw-r--r-- 1 root root   1842 Jul 26  2008 zak.seen

Looks like .spd is the SSH scanner and the .www directory contains the actual bot binary – ok, I can respect that. The contents of the cron.d file suggested that the script utilizes crontab to verify that the bot is always up and running – and examination of its code assured me of that.

So, what have we learned from the above: just one thing! When installing a server for the first time, DON’T USE A SILLY PASSWORD LIKE 123456 – EVEN NOT FOR THE INSTALLATION PHASE! Scanning robots appear to be scanning the entire Internet over and over and over again, doing so in seconds – so by the time you install your server, set it up completely, there is a good chance it will already be compromised.