AI Offensive Testing Specialist

Next Ventures; Brussel Hoofdstad; Hybrid; EUR 90,000 - 120,000; Full time

Job summary

Next Ventures, a leading international financial services organisation, seeks an AI Offensive Testing Specialist to join the CISO Offensive Security team in Belgium. You will perform AI-assisted SAST, DAST and red-team assessments, validate findings and help operationalise an AI security-testing capability.

Location: Belgium/France/UK/Netherlands with hybrid work (eight days onsite per month). Strong Python scripting, SAST/DAST expertise and experience with LLMs are required.

Qualifications

• Three+ years in application security, pentesting or security engineering within enterprise environments.
• Hands-on source-code analysis, SAST/DAST, web/API security testing, pentesting or red-team techniques.
• Experience using LLMs or AI agents for coding, security analysis or automation.
• Ability to assess exploitability, attack paths and remediation options.

Responsibilities

• Execute AI-assisted SAST, DAST, pen-testing and red-team assessments within scope and rules of engagement.
• Prepare testing environments, context, endpoints and credentials.
• Configure and operate LLMs, AI agents, prompts and tools to support security analysis.
• Validate findings for accuracy, reachability and exploitability; filter false positives.
• Produce evidence-rich reports with affected assets and remediation recommendations.
• Collaborate with developers to explain findings and retest fixes.
• Improve prompts, workflows and runbooks for reusable testing patterns.
• Support integrations and operational readiness with appropriate human oversight.

Skills

Python

SAST/DAST

Offensive security

Technical reporting

English proficiency

Tools

LLMs

AI agents

SAST/DAST tools

Job description

A leading international financial services organisation providing post-trade services and financial market infrastructure. Operating in a highly regulated environment, the organisation is developing AI-supported security-testing capabilities to strengthen the protection of its applications and technology platforms.

Position Overview

The AI Offensive Testing Specialist will join the CISO Offensive Security team to deliver application security and offensive testing using LLMs and AI agents.

Working alongside technical leads, security specialists and application teams, you will execute assessments, validate vulnerabilities and produce clear, reproducible findings. You will also help turn an emerging AI security-testing capability into an operational service.

Location: Belgium, France, UK or Netherlands.

Hybrid working: Eight days per month onsite mandatory. UK-based candidates must work through an accredited umbrella company.

Key Responsibilities

• Execute AI-assisted SAST, DAST, penetration-testing and red-team assessments within approved scope and rules of engagement.
• Prepare testing environments, application context, source code, endpoints, credentials and test data.
• Configure and operate approved LLMs, AI agents, prompts and tools to support security analysis and testing.
• Validate findings for accuracy, reachability and exploitability, separating actionable vulnerabilities from false positives.
• Produce evidence-rich reports detailing technical proof, affected assets and remediation recommendations.
• Work with developers and application owners to explain findings and retest corrective actions.
• Improve prompts, testing workflows, runbooks and reusable test patterns.
• Support integrations, deployment validation and operational readiness while maintaining human oversight and approval controls.

Experience Required

• Minimum three years in application security, penetration testing, offensive security, security engineering or software engineering within enterprise environments.
• Hands-on experience with source-code analysis, SAST, DAST, web/API security testing, penetration testing or red-team techniques.
• Practical experience using LLMs or AI agents for coding, security analysis, automation or technical evaluation.
• Ability to assess exploitability, attack paths, control effectiveness and remediation options.
• Coding or scripting skills using Python or an equivalent language.
• Experience with secure cloud or containerised environments, version control, testing, logging and technical documentation.
• Knowledge of relevant frameworks and standards, such as OWASP, CWE, CVE and MITRE ATT&CK or ATLAS.
• Professional English; French or another European language is an advantage.
• Experience helping operationalise an AI, automation or security capability is desirable.