Senior Mainframe Developer Jobs in Fort Mill, SC

Penetration Testing

• Conduct penetration tests against enterprise applications, infrastructure, cloud platforms, AI systems, APIs, mobile applications, Active Directory environments, and other technology assets.

• Simulate real-world attack techniques to identify vulnerabilities, attack paths, misconfigurations, and security weaknesses.

• Perform validation and retesting activities to verify remediation efforts and confirm risk reduction.

• Document technical findings with clear reproduction steps, supporting evidence, business impact, and remediation recommendations.

• Maintain testing artifacts and evidence to support regulatory, audit, and compliance requirements.

Offensive Security Expertise

• Defend findings during discussions with application teams, technology leaders, and other stakeholders.

• Participate in escalation calls involving disputed findings, risk discussions, and remediation planning.

• Exercise sound judgment when assessing vulnerability severity and exploitability.

• Collaborate with internal and external testing teams to improve testing coverage and effectiveness.

• Stay current with emerging attack techniques, technologies, and industry trends.

AI Security and Capability Development

• Contribute to AI security testing initiatives and emerging offensive security capabilities.

• Support AI model evaluation, testing, training, and security validation efforts.

• Provide feedback that improves testing methodologies, automation, tooling, and operational processes.

• Identify opportunities to increase testing efficiency, effectiveness, and scalability.

Quality and Collaboration

• Perform peer reviews of penetration testing reports and deliverables.

• Provide technical guidance and mentorship to junior security professionals.

• Collaborate effectively across security, engineering, development, infrastructure teams, app teams, and various levels of management.

• Assist with standards, procedures, playbooks, and testing documentation.

• Support special projects and security initiatives aligned to individual expertise.

Qualifications
Required Qualifications
The requirements listed below are representative of the knowledge, skill and/or ability required. Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions.

• Bachelor's degree or equivalent education, training, and work-related experience.

• Minimum of 7 years of experience in security engineering or related cybersecurity roles.

• Deep specialized knowledge in cybersecurity principles, theories, and concepts.

• Proven experience in software development lifecycle security practices.

• Deep knowledge of threat modeling, security testing, and penetration testing.

• Experience implementing and managing complex information security technologies.

Preferred Qualifications

• 5+ years of penetration testing, red teaming, offensive security, vulnerability research, or related cybersecurity experience.

• Strong technical writing and communication skills.

• Ability to clearly articulate technical risks to both technical and non-technical audiences.

• Ability to independently manage multiple engagements in a dynamic environment.

• Experience defending technical findings and participating in challenging stakeholder discussions.

• Strong analytical and problem-solving skills.

• Ability to adapt quickly to changing priorities, technologies, and business needs.

• Experience with AI Security Testing and/or Mainframe Security Testing.

• Experience performing assessments in one or more of the following are:

• Experience conducting penetration testing, red team, and security assessments across a variety of environments and technologies, including Active Directory, APIs, web applications, infrastructure, cloud platforms, mobile applications, thick/client-server applications, IoT devices, wireless networks, network security, social engineering, and physical security controls.

• Banking, financial services, or highly regulated industry experience.

• Experience supporting red team, purple team, or adversary emulation activities.
• Experience with scripting, automation, and offensive security tool development.

Desired Characteristics

• Is a self-starter who requires minimal supervision.
• Takes ownership and drives work to completion.
• Performs well under demanding workloads and changing priorities.
• Remains professional and effective during conflict and difficult conversations.
• Is comfortable challenging assumptions and presenting evidence-based findings.
• Continuously invests in improving technical and professional skills.
• Demonstrates resilience, accountability, and a strong bias for action.
• Balances individual execution with team success.
• Helps elevate the performance of those around them.

Relevant Certifications

Candidates may hold one or more of the following industry-recognized certifications:

• Offensive Security (OffSec): OSCP+, OSEP, OSED, OSEE, OSWE, OSWA, OSAI
• GIAC: GPEN, GWAPT, GXPN, GRTP, GCFA
• ISC2: CISSP, CRIS
• Hack The Box: CPTS, Active Directory Penetration Tester, Web Exploitation Specialist, Web Exploitation Expert, Offensive AI Expert

*Equivalent offensive security, penetration testing, red team, exploit development, web application security, or digital forensics certifications will also be considered.

Why Join Us?

You'll work alongside highly skilled security professionals tackling real-world challenges across diverse technologies. Every engagement is an opportunity to learn, improve, and strengthen enterprise defenses. If you're energized by continuous growth, technical excellence, meaningful impact, and the opportunity to help shape the future of offensive security, this is the place to do it.

To comply with the Illinois pay transparency statute and for work locations in Illinois only, the annual base salary for this position is $120,000-$170,000. Additional incentive pay is available for this position.