Senior Offensive Security Engineer Pen Testing & Bug Bounty

PLP Group; Warszawa; On-site; PLN 180,000 - 300,000; Full time

Job summary

Klarna is seeking an experienced Offensive Security professional to perform white-box and black-box penetration testing on internal and public-facing systems. You will triage bug bounty submissions, analyze variants across the stack, and assess third-party integrations for security risks.

The role emphasizes building tooling in Python, guiding development teams, and maturing Klarna's security program through hands-on demonstrations and training.

Qualifications

• 5+ years of penetration testing and security assessments against production systems.
• Able to read and understand code in Java and Node.js.
• Experience operating in AWS and reviewing microservice architectures for security gaps.
• Ability to write clear findings with remediation steps, not just severity labels.
• Scripting in Python and building security tooling.
• Active participation in security community or industry programs.

Responsibilities

• Run white-box and black-box penetration tests against internal systems and public-facing applications.
• Manage, triage, and investigate Bug Bounty submissions and external pentest findings.
• Perform variant analysis to locate similar root causes across codebases.
• Research third-party solutions and integrations for security.
• Build tooling for reconnaissance, automation, and metrics collection.
• Guide developers, product security teams, and SOC investigations with hands-on expertise.
• Run demos, workshops, and training on offensive security practices.

Skills

Penetration testing

Code reading

Python scripting

AWS security

Vulnerability analysis

Security tooling

Clear remediation writing

Tools

Python

Job description

Klarna is seeking an experienced Offensive Security professional to perform white-box and black-box penetration testing on internal and public-facing systems. You will triage bug bounty submissions, analyze variants across the stack, and assess third-party integrations for security risks.

The role emphasizes building tooling in Python, guiding development teams, and maturing Klarna's security program through hands-on demonstrations and training.