Security Engineer
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Summary
Senior Security Engineer - penetration testing, threat modelling, Python. Hands-on offensive and defensive security for web applications. 7+ years. Remote/Hybrid, UK, Chechia, Spain - employment contract, Poland, Romania, Slovakia, Bulgaria, Ukraine - B2B contract.
Are you a talented developer looking for a remote job that lets you show your skills and get decent compensation? Join Upstaff.com, a platform that connects you with hand-picked startups and scale-ups in the US and Europe.
Required Skills
Penetration testing
SecOps
Nice to Have
The role
This is a senior security engineering position with a strong emphasis on penetration testing and threat modeling. You'll work across the full security lifecycle: designing secure architectures, modeling threats, researching emerging attack vectors, and validating defenses through hands-on testing.
The focus is on long-term security improvements — identifying and addressing risks before they become incidents. You'll need both the attacker's mindset to find vulnerabilities and the engineering skills to help fix them properly.
What you'll work on
- Penetration testing and security assessments against web applications and internal systems
- Leading security design reviews and threat modeling for new products and infrastructure changes
- Researching emerging threats and attack techniques, then translating findings into practical defense strategies
- Building security automations and tools, and prototypes to support testing and detection
- Collaborating with engineering teams to remediate vulnerabilities and improve secure development practices
- Contributing to security architecture decisions and standards
What we're looking for
- 7+ years in security engineering with substantial experience in both offensive and defensive work
- Proven, hands-on web applications penetration testing experience
- Strong programming skills, preferably Python, with experience building security tools or automation
- Deep expertise in at least one core security domain: cryptography, authentication/authorisation, secure architecture, or network security
- Clear understanding of attack vectors and methods and how to anticipate them
- Good communication skills in English
Useful additions
- Experience securing serverless architectures or AI/ML platforms
- Background in cloud-native security (AWS, GCP, Kubernetes)
- DevSecOps experience- integrating security into CI/CD pipelines
- Relevant certifications (OSCP, OSCE, CISSP, or similar)