Security Engineer - Offensive Security

Who we are About Cobalt Streamworks Cobalt Streamworks is a financial infrastructure platform for businesses. Millions of companies—from the world's largest enterprises to the most ambitious startups—use Cobalt Streamworks to accept payments, grow their revenue, and accelerate new business opportunities. Our mission is to increase the GDP of the internet, and we have a staggering amount of work ahead. That means you have an unprecedented opportunity to put the global economy within everyone's reach while doing the most important work of your career. About the team The Proactive Threat team is responsible for identifying vulnerabilities and security weaknesses across Cobalt Streamworks's systems, applications, networks, and cloud infrastructure — before adversaries do. We operate as a hybrid offensive function: conducting penetration testing, emulating real-world threat actors through red team operations, and partnering closely with our defensive security teams to validate detection capabilities and improve Cobalt Streamworks's overall security posture. We are builders first. Our team develops custom tooling, automation frameworks, and internal platforms that scale our offensive capabilities and enable repeatable, high-fidelity assessments. We believe the best offensive security engineers are equal parts hacker and engineer. The team is distributed across the United States, primarily operating in Eastern and Pacific time zones, and collaborates regularly with security, engineering, and product stakeholders across Cobalt Streamworks — including teams in Europe and Asia. What you'll do As an Offensive Security Engineer on the Proactive Threat team, you will simulate the tactics, techniques, and procedures (TTPs) of real-world adversaries to uncover security risks across Cobalt Streamworks's products and infrastructure. You'll conduct hands-on penetration testing, lead red team engagements, and collaborate with blue team counterparts to validate and improve detection and response capabilities. Your work will directly influence how Cobalt Streamworks builds, ships, and secures financial infrastructure used by millions of businesses worldwide. Beyond assessments, you'll design and build offensive tooling and automation that amplifies the team's impact. You'll leverage threat intelligence to prioritize testing efforts, contribute to incident investigations when needed, and act as a subject-matter expert for security initiatives across the company. Responsibilities Conduct comprehensive penetration tests across web applications, APIs, cloud environments (AWS/GCP/Azure), mobile applications, and internal infrastructure Plan and execute red team engagements that emulate the TTPs of cyber and criminal threat actors targeting financial services, including initial access, lateral movement, persistence, and data exfiltration scenarios Perform assumed-breach and objective-based assessments to test detection and response capabilities in coordination with defensive teams Partner with detection engineering, threat intelligence, and incident response teams to validate security controls, identify coverage gaps, and improve detection fidelity Contribute adversary tradecraft insights to inform detection rule development, threat hunting hypotheses, and incident response playbooks Support incident investigations by providing offensive expertise, log analysis, and root cause analysis when required Design, develop, and maintain custom offensive tools, scripts, and automation frameworks to enhance assessment efficiency and coverage Build internal platforms and workflows that enable scalable, repeatable offensive operations Contribute to internal security tooling repositories and champion engineering best practices within the team Automate repetitive testing tasks, payload generation, and reporting workflows using modern development practices Produce clear, actionable reports that communicate technical findings, business risk, and remediation guidance to both technical and non-technical stakeholders Act as a subject-matter expert and primary point of contact for stakeholder teams engaged in offensive security programs and Cobalt Streamworks-wide security initiatives Lead offensive security projects end-to-end, mentor junior team members, and foster a culture of continuous learning and knowledge sharing Stay current with emerging threats, vulnerabilities, and attack techniques; share research internally and contribute to the broader security community Who you are We're looking for someone who meets the minimum requirements to be considered for the role. If you meet these requirements, you are encouraged to apply. The preferred qualifications are a bonus, not a requirement. Minimum requirements 5+ years of experience in offensive security, penetration testing, red teaming, or a related field Strong programming skills in Python, Go, or similar languages, with demonstrated experience building tools, automation, or custom exploits Deep knowledge of web application security, including OWASP Top 10, ASVS, and common vulnerability classes (injection, auth flaws, business logic, etc.) Hands-on experience with cloud platforms (AWS, Azure, or GCP), including cloud-native attack techniques and misconfigurations Proficiency with offensive tooling such as Burp Suite, Cobalt Strike, Mythic, Sliver, BloodHound, or similar frameworks Familiarity with adversary tradecraft and frameworks such as MITRE ATT&CK, including TTPs for initial access, privilege escalation, lateral movement, and exfiltration Excellent written and verbal communication skills, with the ability to translate complex technical findings into clear, risk-based recommendations Ability to think like an adversary — creative, persistent, and able to holistically assess risk in complex environments Preferred qualifications Experience conducting offensive security in fintech, financial services, or other highly regulated environments Background in vulnerability research, exploit development, or CVE discovery Experience collaborating with threat intelligence, detection engineering, or incident response teams (purple team operations) Familiarity with big data and log analysis tools (Splunk, Databricks, PySpark, osquery, etc.) for threat hunting or investigative support Proficiency with AI/LLM-assisted development tools (e.g., Claude Code, Cursor, GitHub Copilot) and experience applying them to offensive security workflows Interest or experience in agentic automation — using LLMs or autonomous agents to augment reconnaissance, vulnerability discovery, or exploitation workflows Experience testing AI/ML systems or LLM-based applications for security weaknesses (prompt injection, training data extraction, model manipulation, etc.) Contributions to open-source security tools, published research, blog posts, or conference presentations Relevant certifications such as OSCP, OSWE, OSEP, OSED, CRTO, CPTS, PNPT, GXPN, or cloud security certifications