Senior Security Specialist Red Team in Zoetermeer

Hybrid, at least 3 days a week in the office

Employment

Full-time

Senior, with a path to tech lead

Team

Red Team

You have already run real red team operations and want to take the next step. At DEFION you join a red team that already carries out operations for clients. You help build it further and grow into the technical lead of the unit.

A red team that is already up and running, and that you will build out Our Red Team already carries out red team engagements for clients: realistic attack simulations that show organisations how their prevention, detection and response hold up against a targeted attacker. The team stands on the shoulders of a large offensive security team with years of experience in complex infrastructure, cloud and Active Directory environments. You also work closely with colleagues in incident response and managed detection and response, who see every day how real attackers operate.

We want the Red Team to grow, in size and in capability. For that we are looking for a senior who already has red team experience and wants to set its technical direction.

What you will do Red team operations

You carry out red team engagements and adversary simulations, from reconnaissance and initial access to lateral movement, persistence and achieving the objectives.

You design attack scenarios based on relevant threat actors and their TTPs, mapped to MITRE ATT&CK.

You attack Active Directory, Entra ID and hybrid cloud environments and find your way past modern detection solutions.

You translate attack paths into clear reports for both the SOC and the client’s management, and facilitate purple team sessions.

Between operations you apply your expertise to assume breach, AD and cloud assessments.

Building out the Red Team

Together with the team you develop the red team proposition: which services we offer, to which clients and how we deliver them.

You sharpen the methodology, scenarios, reporting format and OPSEC guidelines.

You help build tooling, C2 infrastructure and evasion capability.

You are the technical sparring partner for sales and clients when scoping red team engagements.

Technical leadership

You take technical ownership of operations and safeguard the quality of the work.

You help recruit new team members and mentor pentesters who want to move into red teaming.

You are a sparring partner for colleagues on complex assignments and technical decisions.

Growing into tech lead You start as a Senior Security Specialist in the Red Team and take technical responsibility for engagements from day one. As the team grows, you grow into its technical lead, responsible for the technical direction, the quality of the work and the development of the people. In your development plan we agree together what that step looks like and what you need to get there.

What you bring Must have:

Several years of experience in offensive security, with a solid grounding in infrastructure, AD and cloud testing

Demonstrable experience with red team engagements, adversary simulation or assume breach assignments

In-depth knowledge of Active Directory, Entra ID and cloud environments (Azure and AWS)

Hands-on experience with at least one C2 framework, such as Cobalt Strike, Sliver, Mythic or Havoc

An understanding of how EDR and other detection mechanisms work and how attackers evade them

You can programme or script, for example in Python, C#, Go or PowerShell

A technical degree at university of applied sciences or university level, or a demonstrably equivalent level

Strong communication skills: you can explain an attack story clearly to engineers and management alike

You like to take the initiative, enjoy building things and want to make others technically better

Nice to have:

Experience leading a red team operation

Experience building your own tooling, implants or EDR evasion

Experience with threat intelligence-led red teaming under TIBER-EU or DORA TLPT

Offensive certifications such as OSEP, CRTO, CRTL or OSCE3

Published CVEs, your own tools or security research

What we offer

Why you will enjoy working here Salary and permanent contract A competitive salary and a permanent contract after the probation period.

Mobility and equipment A mobility budget or lease car, a high-end laptop and a phone.

Training budget A personal budget for certifications and courses, including red team certifications.

Path to tech lead Real influence on how our Red Team grows, and a concrete path to technical lead.

Flexible working Flexible hours, a games room and a gym at the office.

Lunch and events A daily lunch buffet and regular social events.

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