Operational Security Engineer

Mission Overview

Keystone Solutions is hiring an Operational Security Engineer for a consultancy mission within a client's IT Security Production organisation in Brussels. As a Keystone Solutions consultant, you will represent Keystone Solutions while working on the client project, collaborating with business stakeholders, local IT teams and wider group IT partners. You will join a Mainframe System Security squad responsible for establishing security standards, ensuring their correct implementation and compliance, implementing rules to support infrastructure teams, supporting users during security-related incidents, and managing, correcting and documenting security risks identified by auditors. As a Mainframe Operational Security Engineer, you will be a key expert in keeping the client's Mainframe environment secure, compliant and resilient.

Key Responsibilities

Under Keystone Solutions' consultancy model, you will:

• Manage user permissions and access for systems outside IAM, ensuring security without blocking operations.
• Manage the content of the RACF database, either manually or through automation.
• Create clear security documentation and standards so teams understand what to do and why it matters.
• Handle encryption tasks, from importing certificates to configuring technical agents for Hardware Security Modules (HSMs).
• Assess the security of new Mainframe products, ensuring they are safe before going live.
• Collaborate with squad members to resolve security incidents, from decoding error messages to implementing fixes with minimal disruption.
• Support internal clients including IT Risk, Asset Owners and auditors by providing evidence for compliance and addressing audit findings.
• Anticipate potential risks and address them before they become issues for clients.
• Participate in the squad's on-call rotation to resolve critical job failures outside business hours, approximately one week per month, covering non-business hours including weekends and holidays during that week.

Language Requirements

• English: mandatory.
• Dutch: preferable.
• French: preferable.

Education and Certifications

• Bachelor's degree.
• RACF Security Administrator certification: mandatory.
• zSecure RACF certification: preferable.

Working Model and Travel

• Mandatory 50% on-site work in Brussels and 50% homeworking.
• Travel: not applicable.

Required Experience

At least 10 years of relevant experience is required.

Mandatory Technical Knowledge

• RACF and surrounding utilities.
• Mainframe Architecture.
• Basic Mainframe tools including JCL, ISPF, REXX and SDSF.
• Role Based Security Modelling.
• AT-TLS and certificates.
• Security of DB2, IMS, including database and transaction management, and MQ.
• Job Scheduling.
• Mainframe system subsystems and their security, including Spool, network, storage and SMF.
• Public Key Infrastructure and Mainframe CryptoCards.
• Unix System Service.

Preferred Technical Knowledge

• Knowledge of the zSecure product suite.
• Knowledge of the job scheduler Control.
• Knowledge of COBOL.
• Knowledge of Endevor.

Business Experience

• Mandatory: cybersecurity experience, with hands-on Mainframe expertise and the drive to build it further.
• Preferable: experience in the financial sector.

Soft Skills

• Analytical skills: ability to navigate complex scenarios involving conflicting security rules across different manuals.
• Critical thinking: ability to assess requests against security standards rather than taking them at face value.
• Problem-solving: ability to trace vague error messages back to their root cause and implement fixes.
• Creativity: ability to design custom solutions for hundreds of compliance points where no playbook exists.
• Agile mindset: ability to thrive in teamwork while taking ownership of your responsibilities, or eagerness to learn.
• Proactivity: ability to identify risks early in a high-volume environment and resolve them before they escalate.

Why Join Keystone Solutions

This is a consultancy opportunity where you are hired by Keystone Solutions and bring your expertise to a client environment as a Keystone consultant. The model combines meaningful on-site client engagement with exposure to dynamic projects and diverse technical and strategic challenges across client environments. This variety creates turbo-charged learning opportunities, broadens your professional experience and supports skyrocketing ambition through continued career growth within Keystone Solutions.

Being a K-Stone means bringing Keystone Solutions' core values to every engagement, combining technical expertise, accountability, collaboration and a consultancy mindset while delivering value to client projects.

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