Senior Security Specialist

DEFION; Netherlands; Hybrid; EUR 70,000 - 110,000; Full time

Benefits offered by this job

Permanent contract after probation

Mobility budget or lease car

High-end laptop and phone

Personal training budget

Job summary

DEFION is seeking an experienced offensive security professional to conduct security tests across web, cloud, infrastructure, and mobile environments. You will document findings and present results to clients, while choosing an area of specialization that aligns with your interests.

The role offers short, varied projects and the opportunity to shape your own career path, including potential leadership, tooling, and advisory work, in a hybrid setting from Zoetermeer.

Qualifications

• Proven experience with pentesting and security assessments.
• Knowledge of Cloud Security (AWS/Azure), Active Directory, mobile app security, OAuth/SAML, cryptography.
• Experience with tools like Burp Suite, Nessus, or Nmap.

Responsibilities

• Conduct a full range of offensive security tests: web applications, infrastructure, cloud, mobile, and more
• Document findings in detailed reports and present results directly to clients
• Specialize in areas that match your interests: cloud security, red teaming, infrastructure, or security consulting/governance
• Provide security training, advise prospects, and mentor juniors and interns
• Develop and improve internal tooling when that is where your passion lies

Skills

Offensive security

Pentesting

Cloud security

Active Directory

Security reporting

Education

Bachelor's or Master's degree in a technical field

Tools

Burp Suite

Nessus

Nmap

Job description

Hybrid (at least 3 days/week at our office in Zoetermeer)

Employment

Full-time

Team

Offensive Security

You have years of experience breaking things that should not break. At DEFION, you get to shape your own role: tech lead, trainer, consultant, or deep specialist. Your call.

At DEFION, we work mostly with short projects of one to two weeks. That means you will work with many different organizations and application types in rapid succession. Some weeks it is a cloud environment, the next it is Active Directory, then a mobile app. Variety is built into the role.

But beyond that, you shape this position yourself. Want to go deep on red teaming? Become a tech lead? Develop tooling? Train juniors? Advise clients on security strategy? We create the role that fits your strengths and ambitions.

What you will do

• Conduct a full range of offensive security tests: web applications, infrastructure, cloud, mobile, and more
• Document findings in detailed reports and present results directly to clients
• Specialize in areas that match your interests: cloud security, red teaming, infrastructure, or security consulting/governance
• Provide security training, advise prospects, and mentor juniors and interns
• Develop and improve internal tooling when that is where your passion lies

What you bring

Must have:

• Proven experience with pentesting and security assessments
• Knowledge of Cloud Security (AWS/Azure), Active Directory, mobile app security, OAuth/SAML, cryptography
• Experience with tools like Burp Suite, Nessus, or Nmap
• Strong knowledge of common vulnerabilities (XSS, CSRF, SQLi) and how to mitigate them
• A bachelor's or master's degree in a technical field (HBO/WO level)
• Ability to communicate technical findings clearly, both verbally and in writing

Nice to have:

• Published CVEs to your name
• Experience in security consulting or governance advisory

What we offer

Why you will love working here

Competitive package

Competitive salary, permanent contract after probation, mobility budget or lease car, high-end laptop and phone.

Personal training budget

Invest in certifications, courses, or conferences. Grow technically and personally at your own pace.

Diverse projects

Short engagements (1-2 weeks) across many organizations and technologies. Never the same challenge twice.

Shape your role

Tech lead, trainer, tool builder, consultant: you decide where to take your career at DEFION.

Great home base

Game room, gym, daily lunch buffet, flexible hours. Parties, social events, and annual study trips.

Nerdy colleagues

Super social, tech-obsessed, down-to-earth. We share knowledge regularly and have fun while doing it.