Basic Server Hardening

Ok, here is a list of a few programs I’d advise anyone to use who is running a server on the internet (or thinking of doing so).

  • aide or tripwire (they can check and report if files on your system get changed, configurable levels). If you use tripwire, don’t forget a “tripwire –check -I” after you do any updates.
  • logcheck will check your system logs, and report anything out of the ordinary (“ordinary” is defined by a list of ‘normal’ rules, and anything you add)
  • tiger goes farther than logcheck, it actively checks your system and reports anything strange (files not belonging to packages, users or groups that got added, …)
  • grsecurity adds more security features to your kernel (at least use the basic features and the possibility to turn off module loading after boot)
  • rkhunter, chkrootkit scan the system for signs of rootkits or other malware. just install, make sure they are executed daily by cron, possibly tweak rkhunters config a bit (I had problems with unhide and current kernel versions)

I’m not saying that setting up and tweaking all this software and actually reading the emails they generate will make your server super-duper secure, but they will reduce the risk of running a server open to the internet and alarm you if somthing strange is happening. It is important to read and understand what theese programs mail you. Yes, you will get false positives from time to time. And yes, you will have to adjust the config now and then due to package updates; but I get about 3-4 mails a week, and that is definatly ok considering the amount of data that gets checked.

Hackit Contest

Ok, the contest is ready. I’ll start off with the information everybody has been waiting for:


There is a webserver running with a brief description of the target and rules of the contest The webserver is actually part of the contest since people are supposed to deface this page. To make it a bit more interresting, the ssh sessions are recorded with script and saved here for everyone to see (e.g. “less -r filename”).

Rules and Target of the contest:
As stated above, deface this page. To achieve this goal, everything is allowed. Do what you need/want to achieve the goal.
Unfortunatly we will still need a short list of actions that are not allowed:

  • (D)DoS against this box, or via this box against other hosts are
    of course not allowed
  • Brute Force attacks against accounts are not prohibited … but trust me, you really don’t want to waste your time with that
  • Be nice, don’t try to make the accounts or box unusable for others
  • If you are doing something that isn’t aimed at solving the contest, than it probably isn’t allowed

A few details to the box and the system:

  • It is a vmware box (so I can reset it and/or access the console without any problems)
  • Linux debian testing is installed
  • some basic hardening done with normal linux tools and grsecurity
  • Don’t worry, I left enough room for you all to poke around, I didn’t make it “too secure to have fun”
  • This time no holes were intentionally added to the system. On the other hand there will also be no updates of software packages or changes to the RBAC system, no matter what security flaws arise (or I may have overseen)
  • On a scale of 1 to 10: I’d say the security is around 7

Have fun 😉

btw. I’m also posting this in the buha forums for anyone who prefers a German description.

HackIt server nearly ready

I spent the last few days fine tuning the HackIt server I mentioned last week. After lots of thought on how I was going to punch holes into the security, I decided on a different approach. Since in the past contests I always found it fustrating to see people with high skills trying out stuff I would never have dreamed of, and in the end to get beaten by people who by sheer luck tried out the right thing at the right time … I decided to minimize the “luck” factor of the contest by not putting any holes in the server on purpose.

What I am going to do is not update any of the packages any more from now on. I’m doing an update right now as I post this, and from here on no more updates. There will also be no updates or changes to the RBAC system. The only changes I will be making to the box from now on, are if it breaks and needs to be fixed.
-> The box will be shamelessly neglected, waiting to be owned.

If nothing strange pops up tonight, I will be posting information about the contest tomorrow in the buha forum, here and a few other places …

[Work in progress] HackIt Server

The last HackIt I set up was a few years ago, so I decided to have a go at it again. As before it will be a Linux server. And I will also have some fun with grsecurity kernel patches (including the additional Role-Based Access Control system). So nothing new up to here. I’m also going to be using most of the features I used back then too (like “trusted path execution” and no outgoing/server sockets for users, …)
Last time it was separate hardware on my little DSL line (meaning back then all users had to share a 128kbit upstream). This time it will be a vmware box on a 100Mbit Internet connection and it’s own IP, so no more worry about laggy ssh sessions.

I’ll post more details as soon as this gets more “ready-for-release”. Right now I’m still hardening the box, I still haven’t decided on which holes I’m going to build into it to make it a “HackIt”.