Cyber Offensive Security Senior Associate

Grant Thornton • Philadelphia, PA

2d • Hybrid

About The Position

As a Senior Offensive Security Consultant on the Cyber Defense team, this role leads hands-on adversarial testing engagements for clients across industries. The position simulates real-world adversaries to identify exploitable weaknesses, validate detection and response capabilities, and help clients strengthen their security posture. It involves substantial client interaction and communicating technical findings and their impact to technical teams and executive stakeholders.

The role conducts network, application, API, and cloud penetration tests; threat-informed adversary simulations; assume-breach engagements; and security testing of AI/ML systems and LLM-enabled applications. It also includes emulating threat actors, producing client-ready reports and remediation guidance, advising clients on risk and security-program maturity, and contributing to practice methodologies, tooling, automation, and junior-team-member mentoring. The position follows Grant Thornton’s hybrid work model and requires in-person attendance at least three days per week at a Grant Thornton office or client site.

Requirements

• Bachelor’s degree in Cybersecurity, Information Technology, Computer Science, or a related field.
• At least 3 years of hands-on experience in offensive security, penetration testing, or red teaming.
• Demonstrated expertise across multiple testing domains, including network, application, cloud, and/or internal infrastructure.
• Strong understanding of adversary tactics, techniques, and procedures and frameworks such as MITRE ATT&CK, ATLAS, and OWASP.
• Proficiency with industry-standard tooling and command-and-control frameworks.
• Scripting and automation skills, such as Python, PowerShell, or Bash.
• Experience conducting assume-breach or adversary-emulation engagements.
• Excellent written and verbal communication skills, including the ability to produce professional, client-ready reports.
• Ability to work independently, manage multiple engagements, and meet deadlines in a client-service environment.

Nice To Haves

• Relevant certifications such as OSCP, OSEP, OSWE, GPEN, GXPN, GWAPT, or CREST.
• Prior consulting or professional-services experience.
• Cloud security testing experience across AWS, Azure, and/or GCP.
• Experience with AI/ML or LLM security testing and adversarial techniques.
• Familiarity with breach and attack simulation platforms.
• Experience testing the security of D365 and integrations.
• Contributions to the security community, such as research, tooling, CVEs, conference talks, or publications.

Responsibilities

• Plan and execute network, application, API, and cloud penetration tests from scoping through exploitation, post-exploitation, and reporting.
• Design and run threat-informed attack simulations to validate client security controls and detection coverage.
• Conduct assume-breach engagements with defensive teams to test detection, response, and containment capabilities.
• Perform adversarial testing of AI/ML systems and LLM-enabled applications, including prompt injection, model manipulation, data exfiltration, and abuse-case testing.
• Emulate relevant threat actors’ tactics, techniques, and procedures, mapping activity to frameworks such as MITRE ATT&CK.
• Produce clear, high-quality deliverables translating technical findings into prioritized, business-relevant remediation guidance.
• Present engagement results to technical staff, management, and executive or board audiences.
• Advise clients on risk, remediation priorities, and security-program maturity.
• Contribute to methodology development, tooling, and automation.
• Mentor junior team members.

Benefits

• Personalized and comprehensive benefits; specific benefit details are available through the company’s rewards and benefits page.
• Employees may be eligible for a discretionary annual bonus based on individual and firm performance, subject to applicable plan terms, conditions, and eligibility criteria.
• Flexible work options involving work location, weekly schedule, or flex time off.
• Work-life integration options and support for overall well-being.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior