Senior Security Specialist – Penetration Testing

LSEG is seeking a Senior Penetration Tester to join our internal offensive security team. This role is hands-on and deeply technical, responsible for planning and executing penetration tests across a wide range of systems and applications. The successful candidate will be a skilled offensive security professional with a passion for uncovering vulnerabilities and improving security posture through rigorous testing and collaboration. 

Key Responsibilities 

• Conduct in-depth penetration tests on applications, infrastructure, and cloud environments. 

• Take full ownership of assigned pentesting engagements end-to-end and deliver with limited oversight.  

• Compile technical scoping documents, track and document assessment metadata 

• Engagement details (who, what, when, where) 

• Testing team members and roles 

• Tools and methodologies used 

• Schedule and timelines 

• Target systems and environments 

• ConstraintSenior Security Specialist – Penetration Testing 

• s, exclusions, and limitations 

• Testing activities and event logs 

• Document findings clearly and concisely, providing actionable remediation guidance.  

• Collaborate with application teams to scope, execute, and report on security assessments. 

• Contribute to team improvement efforts and ensure all initiatives and feedback are well documented for future references.  

• Contribute to the continuous improvement of testing methodologies, tooling, automation.  

• Stay current with emerging threats, vulnerabilities, and offensive security techniques. 

• Participate in R&D initiatives as guided from leadership. 

• Support knowledge sharing and mentoring within the team. 

• Develop and maintain custom tools, scripts, and exploits to support testing activities. 

Required Skills & Experience 

• Proven hands-on experience in penetration testing of Web Applications, APIs, Thick Client and Common Infrastructures (Active Directory, Cloud and Cloud-native based environments). 

• Proficiency with tools such as Burp Suite, common command-line tools, and ability to write custom scripts when needed. 

• Experience in automating pentesting tasks. 

• Strong understanding of application security, network protocols, and operating systems. 

• Experience with cloud platforms (AWS, Azure, GCP) and containerized environments (Docker, Kubernetes). 

• Ability to write clear, technical reports and communicate findings to both technical and non-technical stakeholders. 

• Experience working in large, complex enterprise environments. 

• Fluent communication skills in English, both written and verbal. 

• Relevant certifications and engagement with the security community is a plus 

• Threat Modelling experience is a plus. 

• Experience working in large, complex enterprise environments. 

• Proven track record of successfully managing and executing security engagements for various organizations with differing operational and technical profiles. 

• Ability to identify, assess, and communicate technical and project risks to stakeholders. 

• Understanding project requirements and aligning deliverables with agreed upon objectives and timelines.