Download of my Thesis and Presentation

thesis_coverI received the permission to publish my thesis and presentation today from my university. So here you go!
You can now download my thesis with the title “An Analysis of the Tor Network” directly from my server. I hope that this is an interesting read for you. Unfortunately it is in German. The whole title in German is “Eine Analyse des Tor-Netzwerks: Konzept, Funktionsweise und Angriffe”.

Here is my presentation which I used in the colloquium to present my thesis, explain my motivation and showed the key results.

The thesis was rated with grade 1,3.

Update: In case you have any questions regarding this topic or my thesis, just ask and I’ll try to answer it. 🙂

Restoring WhatsApp Chats after Shooting Rampage in Munich

I guess you have seen it in the news: On Friday 22nd July 2016 afternoon, a 18-year old teenager started a shooting rampage in the Olympia-Einkaufszentrum (OEZ) in Munich and committed suicide afterwards. In the last days a 16-year old friend of the attacker contacted the police. The police applied for an arrest warrant for the 16-year old boy because they feared he might manipulate possible evidence and indices.

Actually he already tried to clear some traces. In the meantime the police in Munich was able to check his smartphone and found that both friends have met some hours before the rampage at the OEZ and had a chat conversation via WhatsApp. His friend deleted the chat session in WhatsApp. However, the police was able to restore the chat session.

whatsapp_database_backupIt’s interesting how this is possible, but actually it is not that difficult! 🙂
WhatsApp stores a local backup of your chats on your smartphone. On my personal Samsung Galaxy Note 4 there are nine backup files for the last nine days. Every day at 2 am WhatsApp creates a new backup and deletes the oldest one. Additionally you can set up WhatsApp to create a further backup online for example in Google Drive.


The restore is stupid, simple. If you uninstall WhatsApp and re-install it, it looks for recent backup files and asks, if it should restore the latest backup. If you say “yes”, all your deleted chats and messages are restored. It uses always the latest backup. So if you want to restore the backup that was created four days ago, you just have to change the file name so that WhatsApp recognizes the required backup file as “last” backup and restores it.

So, bad luck for the 16-year old teenager, but good for the police to investigate the rampage and the motives of the attacker further.

Package Repository in Kali Linux

I’m currently setting up my VMs according to the “Penetration Testing” book, I’ve wrote about last time. During the setup you need to install additional packages like mingw, etc. On my machine, the command

finished with error: “Unable to locate package …”.

If you search the internet for this issue you will get lots of advice how to change the source.list file in Kali. Most of them just say: ‘Copy these x lines and you’ll be fine.’. But you have to be careful. Offensive Security explains in the Kali documentation how to set up the sources.list file correctly. Here is a link to this documentation. Instead of just adding more an more repositories, you should check if the required package is available in the Kali repository. Sometimes the name of the package may have been changed.

Here you can search all packages in the Kali repository. This was helpful for me and I found the missing packages this way.

This morning I saw on Twitter another article about the Kali repository. Maybe this is helpful, too.

Podcast: Building a Life and Career in Security

Today I would like to recommend a podcast that I’m regularly listen to.

I’m trying to move into an information security career. So I’m very interested in the stories of people, who are successfully working in this particular field of information technology.

On my daily way to work I often listen to various podcasts. Most of them are IT or specially InfoSec related. One of my favourite podcasts that meet all points is the “Building a Life and Career in Security” podcast by Jay Schulman. It is about IT/InfoSec (check), it is about people’s stories (check), and the host Jay Schulman talks about the way of his guests into the infosec field and their personal and professional background (check, check, check!).

If you are interested in getting into the IT security field I can strongly recommend this podcast! You will hear lots of different stories and get to know a lot of different jobs in this industry. And there are around 2 to 3 new episodes each month, which is a perfect publication period.

Do you know other podcasts or blogs, that are covering this topic (infosec + career stories)?

Penetration Testing Book by Georgia Weidman

In my previous post I’ve already mentioned that I will keep up learning new stuff. The title of my blog is securitypath and so security topics will be mostly present here. In the future I would like to get my foot in the door in the security industry. The most interesting part is the whole blue team / red team approach, where the blue team is defending and hardening the systems and infrastructures and the red team is trying to get around these things and get control of the target boxes.

Some days before I saw on Twitter a nice piece of code as infinite recursion. Starting with a new idea, losing motivation, abandon project and then having the next idea again. So according to this I’m currently at the “start with new idea” step, again. 🙂

pentest-weidmanAt next I will work through the book “Penetration Testing – A Hands-On Introduction to Hacking” by Georgia Weidman. Publisher is No Starch Press. My copy is from 2014 but I think this is the first and latest edition of this book until today. I saw many positive recommendations and a lot of love for this book on and also, so I decided to get a copy of it.

At the moment I’m still in the beginning, chapter 1. This chapter is all about getting your penetration test lab started. You learn to set up Kali Linux with some additional tools like Nessus (a vulnerability scanner, which has a free version). And you set up a Linux box and a windows box, which work as vulnerable victims for your attacks.

The next chapters will walk through the penetration testing cycle with information gathering, finding vulnerabilities, exploitation and post exploitation. There are much more detailed chapters, but that seems to be the recurring theme through the book.

My goal is to get my hands dirty and to reach some hands-on pentesting skills, even if it’s on a low level. Currently I’m considering if I should approach to the OSCP (Offensive Security Certified Professional) certification in Pentesting because of the workshop content, the exam and the certification in the end. But this will be a challenging task and at first I want to finish the Pentesting book.
In my next posts I will report how it works out and which problems or success stories I experienced during my approach.