[Hiring] Security Engineer @Whatnot

Role Description

• Plan and run authorized red team operations across cloud (AWS), Kubernetes, networks, identity systems, SaaS, and internal applications, under written rules of engagement.
• Build and maintain AI-assisted testing harnesses: agent loops that run recon, attack-path discovery, fuzzing, and exploit validation with logging, scoping controls, and human approval gates.
• Use LLMs and agentic tools to speed up vulnerability research, payload and test-case generation, code review, and report drafting, and measure where they help and where they mislead.
• Red team our own AI systems: prompt injection, tool and connector abuse, data exfiltration, model and agent permission boundaries, and supply chain risk in AI dependencies.
• Emulate realistic adversaries using MITRE ATT&CK and ATLAS, chaining findings into end-to-end attack paths rather than isolated bugs.
• Run purple team exercises with detection engineering and incident response, and tune detections based on what your tests evade.
• Write clear findings with reproduction steps, impact, and recommended fixes; track remediation to closure and retest.
• Automate regression tests so fixed weaknesses stay fixed, and feed results into CI/CD pipelines.
• Document and share techniques, tooling, and lessons learned with engineering teams.
• Work collaboratively with Whatnot’s Blue Team on Purple Team engagements to help strengthen Whatnot’s overall security posture.

Qualifications

• 3+ years in offensive security, red teaming, or penetration testing, with real engagements against production-scale environments.
• Strong programming skills in Python; you write your own tooling instead of only running others.
• Hands-on experience building LLM-powered workflows or agents (tool use, orchestration, evaluation, guardrails), not just prompting a chat window.
• Deep knowledge of at least two areas: cloud security and IAM abuse, Active Directory or identity attacks, Kubernetes and container escapes, web and API exploitation, CI/CD and supply chain attacks.
• Working knowledge of AI-specific risks: prompt injection, insecure tool use, data leakage, excessive agent permissions, and model supply chain issues.
• Sound judgment on scope, safety, and blast radius; you know how to test production-adjacent systems without causing outages.
• Clear written communication: reports an engineer can act on and an executive can skim.

Benefits

• Generous Holiday and Time off Policy
• Health Insurance options including Medical, Dental, Vision
• Work From Home Support
• Home office setup allowance
• Monthly allowance for cell phone and internet
• Care benefits
• Monthly allowance for wellness
• Annual allowance towards Childcare
• Lifetime benefit for family planning, such as adoption or fertility expenses
• Retirement; 401k offering for Traditional and Roth accounts in the US (employer match up to 4% of base salary) and Pension plans internationally
• Monthly allowance to dogfood the app
• Parental Leave: 16 weeks of paid parental leave + one month gradual return to work (company leave allowances run concurrently with country leave requirements which take precedence).

Company Description

Whatnot is the largest live shopping platform in North America and Europe to buy, sell, and discover the things you love. Whether it's trading cards, fashion, electronics, or live plants, our sellers are building real businesses across hundreds of categories. We're building live commerce at a scale that's never been done in the West, and there's no playbook to copy.

As a remote co-located team, we're inspired by our values and anchored in hubs across the US, UK, Ireland, Poland, Germany, and Australia. We move fast, stay close to our users, and focus on the work that drives the most impact.

We're one of the fastest growing marketplaces and were recently named the #1 Best Startup Employer in America by Forbes.