Work experience

Cyber Engineer
Thales Nederland B.V., Huizen

Nov. 2020-Now

I work in the Cyber Defense team of Thales Nederland in Huizen. This team provides Managed Security Services both internally for Thales Nederland as well as a number of external companies. These managed services include a SOC-as-a-Service, pentesting, consultancy and digital forensics. As a Cyber Engineer I, currently, work in our Red Team, but this is also a role which asks me to often to switch to the other domains. During time at Thales I gained experience with the following subjects:

  • Pentesting internal (Active Directory) networks (OSCP, CRTP and CRTO certified)
  • Pentesting external facing resources/websites
  • Code review(s)
  • Setting up and executing phishing campaigns
  • Writing scripts to enrich our reports / make it easier to generate them
  • Engineering detection rules
  • Forensic investigations
  • (Technical pre-)sales (including Financial Administration)
  • Log source connecting
  • Log message parsing
  • High-level design and implementation of SIEM rules

Research intern
Secura B.V., Amsterdam & Eindhoven

Mar. 2019-Nov. 2019

I worked on the ASCLEPIOS project by researching different Attribute-Based Encryption schemes. In this project, subsidised by the European Union, a consortium of 11 universities, medical centers and businesses collaborates to develop a Union wide platform to share medical data securely using Searchable, Attribute-Based and Functional Encryption.

Education

Master Cyber Security (4TU Federation)
University of Twente (graduated)

Sept. 2017-July 2020

In this master's programme I studied topics such as:
- Cyber Risk/Security Management
- Cryptography
- Privacy-Enhancing Technologies
- Network/IoT Security
- Software Security
- Cyber Data Analytics
- E-Law
Website: 4TU Master Cyber Security

Thesis: Experimental Review of the IKK Query Recovery Attack: Assumptions, Recovery Rate and Improvements, where I reviewed and improved an attack on Searchable Encryption schemes. The paper was published and presented at the 19th International Conference on Applied Cryptography and Network Security (ACNS 2021). I graduated with a 9/10.

Bachelor Technical Computer Science
University of Twente (graduated)

Sept. 2013-Aug. 2017

Minor on European Union (European Public Administration)
Thesis: Performance of Multicast over Unicast in WiFi

Extra curricular activities

Member Advisory Board
Nationaal informatica Congres (SNiC), Utrecht

Nov. 2016-Sept. 2020

I was a member of the Advisory Board of the foundation that organises the national student congress on IT. I advised the board of the foundation on organisational and financial matters regarding the annual congress
Website: SNiC

Several committees
I.C.T.S.V. Inter-Actief, Enschede

Dec. 2013-Sept. 2020

Treasurer Bar Committee

Sept. 2017-Sept. 2018

Member Audit Committee

Sept. 2016-Sept. 2018

Computer skills

Hacking targets/tools

(Kali) Linux: Experienced

Windows: Experienced

Active Directory: Experienced

Metasploit: Experienced

Impacket: Experienced

Cobalt Strike: Learning

Programming languages

Python: Experienced

LaTeX: Experienced

Haskell: Experienced

Java: Experienced

HTML/CSS: Capable

SQL: Capable

Interests

CTF team
I started a CTF (Capture the Flag) team. We participated in multiple CTF events, including one which was organized by the Dutch government (participated twice). These competitions require multi-disciplined knowledge and/or the ability to quickly learn and understand new subjects to solve various technical challenges.

The following websites either point to my personal account or to the account of my team:
CTFtime.org
CTFLEARN
TryHackMe
HackTheBox

Board years

Treasurer & (formerly) General board member
Alumni association ENIAC, Enschede

Sept. 2020-Now

ENIAC (ENschedese Informatica Alumni Club) is the association for all students that received a bachelor's degree in Computer Science or Business & IT or any of the related master's at the University of Twente. Within ENIAC the board is responsible for organising activities to promote both contact between the members of the association as well as contact between the members of the association and (the members of) study association Inter-Actief.
Website: ENIAC

Chairman
Stichting Borrelbeheer Zilverling, Enschede

Oct. 2016-Oct. 2017

This foundation is responsible for managing the drink rooms including inventory management, and asset planning for drinks of six study associations at the University of Twente. As chairman, my main responsibility was preparing and leading meetings of the board, ensuring smooth communication with the associations and negotiate contracts with our partners
Website: SBZ

Officer of Internal Affairs
I.C.T.S.V. Inter-Actief, Enschede

Sept. 2015-Sept. 2016

I was a full-time board member of the study association for Technical Computer Science and Business & IT. My main responsibility was facilitating the integration of members into the association by encouraging students to partake in extra-curricular activities. Other tasks included the supervision of several committees, the improvement of the association according to the long term vision of my board, and the representation of the association towards other University bodies at a local and national level
Website: Inter-Actief

Languages

Dutch: Native Language

English: Proficient

Contact information

E-mail: ruben[@]grootroess.ink

E-mail: r.grootroessink[@]alumnus.utwente.nl

Website: https://grootroess.ink

LinkedIn: Ruben Groot Roessink

© Ruben Groot Roessink,