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Grant Thornton

Audit, tax, and advisory professional services

Cyber Offensive Security Senior Associate

Offensive Security & TestingConfirmed live in the last 24 hours
Full-timeNo salary listed

About the Job

Requirements

  • A bachelor's degree in Cybersecurity, Information Technology, Computer Science, or a related field is required.
  • At least 3 years of hands-on experience in offensive security, penetration testing, or red teaming.
  • Demonstrated expertise across multiple domains, including network, application, cloud, and/or internal infrastructure testing.
  • 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.

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 the effectiveness of client security controls and detection coverage.
  • Conduct assume-breach engagements, collaborating 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 the tactics, techniques, and procedures of relevant threat actors, mapping activity to frameworks such as MITRE ATT&CK.
  • Produce clear, high-quality deliverables that translate technical findings into prioritized, business-relevant remediation guidance; present results to technical staff, management, and executive or board audiences.
  • Serve as a trusted technical advisor, helping clients understand risk, prioritize remediation, and mature their security programs.
  • Contribute to methodology development, tooling, automation, and mentoring junior team members.

Desired Qualifications

  • 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 through research, tooling, CVEs, conference talks, or publications.

About the Company

Grant Thornton

Audit, tax, and advisory professional services

Grant Thornton provides audit, tax, and advisory services to a broad range of clients, including public and private companies, government agencies, and non-profit organizations. Its services are delivered on a fee-for-service basis with tailored offerings in financial reporting, tax compliance, risk management, and business consulting, supported by technology-driven solutions. The firm differentiates itself through a strong emphasis on personalized client attention, deep industry knowledge, and long-term relationships, along with a wide range of sector experience and practical, hands-on guidance. The company’s goal is to help clients navigate complex financial environments, meet regulatory requirements, manage risk, and achieve their business objectives by delivering clear insight and reliable support.

Company size
10,001+
Company stage
Not listed
Total funding
Not listed
Headquarters
Chicago, IL
Founded
1924

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