Senior Offensive Security Engineer

Overview

In this role you will lead penetration testing efforts for Klarna’s internal and public systems, triage bug bounty submissions and external pentest findings, and propagate security insights across teams. You’ll analyze issues across the codebase and infrastructure, build tooling, and mentor engineers and SOC colleagues. The position sits on the Offensive Security team and centers on maturing Klarna’s security program. This is a hands-on, impact-driven opportunity in a fast-moving fintech environment.

Responsabilità Run white-box and black-box penetration tests on internal and public-facing systems

Manage triage and investigation of Bug Bounty submissions and external pentest findings

Perform variant analysis to identify related issues across the codebase and infrastructure

Assess security of third-party solutions and integrations

Build tooling for reconnaissance, automation, and metrics collection

Guide developers, product security teams, and SOC investigations with practical recommendations

Lead demos, workshops, and training to spread offensive security practices

Assess overall security of Klarna’s tech stack and contribute to maturing the security program

Requisiti fondamentali 5+ years of conducting penetration tests and security assessments on production systems

Ability to read code and identify vulnerabilities in Java and Node.js

Experience with AWS and microservice architectures

Clear, remediation-focused writing that translates findings into actionable steps

Python scripting to develop own tooling

Proactive, self-driven approach to advancing offensive security within the organization

Clear written and verbal communication

Initiative and self-motivation

Collaboration across cross-functional teams

Penetration testing and security assessments

Java and Node.js code review

AWS cloud security and microservices