Senior Offensive Security Engineer

Pro Circular is a cybersecurity firm that helps organizations see where they’re vulnerable, understand how those gaps get exploited, and build a security program grounded in the real world. We invest in advanced cybersecurity and AI research, then translate complex findings into practical guidance and solutions our clients can actually use. Across assessments, monitoring, incident response, advisory, AI risk, and compliance, Pro Circular brings deep technical expertise, practical judgment, and a team that stays involved from initial findings through response and longer-term program development.

Trusted by organizations across healthcare, finance, manufacturing, education, transportation and logistics, and government, where downtime and risk carry real operational weight, Pro Circular helps teams move from reactive security work to confident decisions, stronger readiness, and better follow-through.

You will run network penetration tests for organizations across the Midwest, and you will help us build our artificial intelligence (AI) red team practice from the ground up.

Most of your first year is traditional offensive work: internal and external network testing, owned end to end. The AI side is real and growing, and the person in this seat gets to define how we do it. We are not looking for someone to execute a playbook that already exists. We are looking for someone to write it.

• Plan and execute internal and external network penetration tests, from scoping through remediation guidance.
• Run engagements independently. You own the scope, the testing, the report, and the client readout.
• Write findings a system administrator can act on and an executive can understand.
• Present results to technical teams and to leadership, including IT directors, executive sponsors, and boards.
• Retest remediated findings and help clients actually close gaps rather than just cataloging them.
• Contribute to purple team exercises and adversary simulation work as engagements call for it.

This part is greenfield. You will be building the offering, not inheriting it.

• Design our testing methodology for AI systems: chatbots, autonomous agents, retrieval augmented generation (RAG) pipelines, and Model Context Protocol (MCP) servers.
• Test for prompt injection (both direct and indirect), tool abuse and excessive agency, guardrail bypass, sensitive data exposure through agent tool chains, and unsafe handling of model output.
• Assess MCP servers and agent integrations for authorization gaps, over-permissioned tools, tool poisoning, and insecure defaults.
• Map our work to recognized references including the OWASP Top 10 for Large Language Model Applications, MITRE ATLAS, and the NIST AI Risk Management Framework.
• Turn what you learn into a repeatable service: scoping questions, test plans, report templates, and input on how we price the work.

We expect our senior engineers to build, not just run other people's tools.

• Write and ship internal tooling that makes testing faster and more consistent across the team.
• Automate the repetitive parts of reconnaissance, validation, and reporting.
• Bring an offensive perspective to our internal security products and help make them better.
• Python is the common language on our offensive team.

The requirements listed below are representative of the knowledge skills and abilities required. Employees who do not have the requirements for a job at the time of hire will not be considered for the position. Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions.

• Five or more years of hands-on…