Job Description

The role

We are looking for technically gifted and strategically minded Penetration Testers to deliver and lead offensive security engagements across diverse environments. You’ll simulate sophisticated attack scenarios, uncover vulnerabilities, and provide strategic recommendations that help our clients reduce risk and enhance their overall security posture.

As a Senior Consultant or Manager, you’ll assess infrastructures, applications, and cloud environments through ethical hacking engagements and work closely with clients to strengthen their resilience against evolving cyber threats.

Key Responsibilities

• Plan, execute, and report on penetration testing engagements across network infrastructure, web and mobile applications, cloud environments, and APIs.
• Deliver advanced threat emulation, social engineering, and red/purple team assessments, including Threat-Led Penetration Testing (TLPT) and TIBER exercises.
• Analyse and communicate technical findings clearly, providing actionable recommendations tailored for both technical and executive stakeholders.
• Provide strategic remediation advice to help clients address vulnerabilities and build long-term resilience.
• Collaborate with internal threat intelligence, incident response, and governance teams to provide holistic cyber defence solutions.
• Develop and enhance custom tools, scripts, and proof-of-concepts to improve testing effectiveness.
• Contribute to knowledge sharing, methodology development, and team mentoring, depending on seniority.
• Support business development initiatives through proposal input, presentations, or technical scoping discussions (Senior Consultant level).

Skills & Experience

• Bachelor’s degree in Computer Science, Cybersecurity, or a related discipline (or equivalent practical experience).
• 3+ (5+ for Manager) years of hands-on penetration testing or offensive security experience.
• Proficiency with tools such as Burp Suite, Nmap, Metasploit, Cobalt Strike, Nessus, and similar toolsets.
• Deep understanding of common attack vectors, including OWASP Top 10, MITRE ATT&CK, and cloud-specific threat models.
• Strong scripting capability in Python, PowerShell, or similar languages.
• Relevant certifications such as OSCP, OSCE, CREST CRT/CCT, GPEN, or equivalent industry-recognised credentials.

Desired Skills

• Experience testing cloud platforms (AWS, Azure, GCP) and container environments (Docker, Kubernetes).
• Proven ability to lead client workshops, present findings, and manage sensitive or complex client discussions.
• Familiarity with compliance frameworks and regulations such as PCI-DSS, ISO 27001, NIST, DORA, and NIS2.
• Excellent report writing and communication skills, with the ability to translate technical findings into actionable insights for business leaders.

#LI-RM1

We are Grant Thornton
Grant Thornton Ireland is rapidly approaching 3,000 people, in 9 offices across Ireland, Isle of Man, Gibraltar and Bermuda. With a presence in over 149 countries around the world and a global network of 73,000 people, we bring our clients the local knowledge, national expertise and global presence to help them succeed – wherever they’re located.

At GT, we work as trusted advisors, bringing local knowledge and national expertise, with a global presence, to help businesses succeed – wherever they are located. We make business more personal by investing in building relationships and empowering our clients to make the right decisions for their organisation now and for the future. Whether that is working with the public sector to build thriving communities, with regulators and financial institutions to build trust, or with a diverse range of businesses to help them achieve their goals, Grant Thornton Ireland work hard to support clients to act on the issues that matter.

At GT Ireland we don’t just predict your future, we build it
A Career at GT
Looking for a more fulfilling role in professional services? One where fresh thinking, collaboration and diversity are valued? At Grant Thornton we do things differently.

What does this mean for you?
A career in a more inclusive working environment, a more collaborative work culture, a more supported, flexible working role, more possibilities to grow and more opportunities to help shape the future for your clients. We respect and value your experience. And we want you to bring your authentic self to work and be at your best. It is how it should be.

Grow with us
At Grant Thornton, we care about our people and work hard to make you feel valued. If you are looking to deepen and develop your skills, knowledge, and experience throughout your career, then that is what you will get, and more.
Our Benefits
Please follow this link for information on our generous benefits package.