Senior Application Security Specialist

About the Company:

Publicis Re:

Sources is at the core of Publicis Groupe, the world's largest communications company. We are the only full-service, end-to-end shared service organization in the industry, enabling Groupe agencies to do what they do best: innovate and transform for their clients.

Formed in 1998 as a small team to service a few Publicis Groupe firms, Publicis Re:

Sources has grown to 6,000+ employees in over 55 countries. We provide technology solutions and business services, including finance, accounting, legal, benefits, procurement, tax, real estate, treasury and risk management, information security, and global mobility — supporting 110,000+ employees across the Publicis Groupe network. Our people are at the center of everything we do, bringing curiosity, collaboration, and a commitment to excellence to their work every day.

Learn more about Publicis Re:

Sources and the Publicis Groupe agencies we support at

Job Scope & Responsibilities:

• Core Penetration Testing:
Conduct in-depth penetration testing across web applications, mobile applications, thick clients, cloud-native applications, APIs, and network environments using a combination of automated tools and manual testing techniques.

• AI, LLM, Agentic AI & MCP Security Testing:
Assess AI chatbots, AI agents, LLM-powered applications, and Model Context Protocol (MCP) servers to identify risks introduced by AI systems and evaluate how those risks can be tested, governed, and reduced.

• AI Security Test Execution:
Design and execute hands-on test scenarios covering prompt injection, tool exploitation, jailbreaks, harmful outputs, sensitive data exfiltration, excessive agency, hallucination, grounding failures, policy bypass, and other AI-specific attack patterns.

• AI-Enabled Testing & Automation:
Build and use AI agents, agent skills, and automation workflows to execute repeatable security tests, automate adversarial prompt execution, validate guardrail behaviour, analyse responses, and accelerate testing activities.

• Reporting & Remediation:
Identify, classify, and prioritize vulnerabilities based on risk and business impact. Prepare clear reports that include findings, evidence, proof-of-concept details where applicable, and practical remediation guidance.

• Collaboration & Delivery Support:
Work with internal security, development, and project teams to understand application functionality, validate risks, communicate findings, and support remediation discussions within the agreed engagement scope.

• Continuous Learning:
Stay current with emerging security threats, vulnerabilities, technologies, AI security risks, and evolving testing methodologies.

• Methodology & Process Contribution:
Contribute to agreed security testing templates, reporting formats, methodologies, and process documentation required for consistent and efficient engagement delivery.

Required Job Profile:

• Bachelor’s degree in computer science, information security, or a related discipline.

• 4 Plus years of hands-on experience delivering vulnerability assessment and penetration testing engagements across application and technology environments.

• Strong understanding of Industry known standards like OWASP, SANS, OSSTMM, PTES, and NIST

• 2 Plus years of hands-on experience securing and pentesting AI/LLM applications, agentic workflows, RAG, tool/function calling, and MCP-based systems, with expertise in identifying and validating risks such as prompt injection, jailbreaks, tool abuse, privilege escalation, data exfiltration, unsafe actions, guardrail bypass, hallucinations, grounding failures, and model abuse.

• Hands-on experience creating agent skills, building and configuring AI agents, integrating tools and workflows, and using automation to streamline…