Cyber Security Engineer — Infrastructure & AI Platform Security (f/m/d) (Karlsruhe)

About IONOS

At IONOS, we don’t just manage servers – we shape the digital future for more than 6.2 million customers worldwide with our solutions. As Europe’s leading hosting provider and a pioneer in independent cloud solutions, we are building next-generation infrastructure – from sovereign cloud architectures and high-performance GPU clusters to integrated AI automation tools.

What drives us is digital sovereignty for Europe and real impact for small and medium-sized businesses (SMBs) as well as large enterprises. We work in agile teams, rely on transparent structures, and believe that excellence and innovation only emerge through true team spirit.

Ready for your next step? Become part of IONOS and grow with us.

Both halves of this role are about the same underlying question: which systems can reach our most sensitive infrastructure, and under what controls. You will own the security architecture for our provider-side infrastructure layer, and you will be the subject matter expert for the AI platforms and agents we operate internally, making sure they run in a secure, governed, auditable state rather than accumulating quietly as a new class of privileged access.

This is a hands-on expert role. You set standards, pressure-test designs, and work directly with platform and engineering teams across our brands to get them implemented.

Tasks

Internal AI platform and agent security

• Define and maintain security architecture standards and hardening baselines for provider-side infrastructure: virtualization and container platforms, control planes and provisioning systems, DNS, mail infrastructure, and backup and recovery systems.
• Assess and strengthen tenant isolation across shared hosting, virtualization, and container layers, and drive remediation with the responsible platform teams.
• Review infrastructure designs and major changes for security impact, and act as an escalation point for infrastructure security questions from platform, cloud, and brand engineering teams.
• Reduce blast radius on the paths that matter most: privileged access to customer-facing infrastructure, administrative segmentation, secrets handling, and recovery integrity – translated into workable per-brand implementation plans across our heterogeneous platforms.
• Support Cyber Defense, Vulnerability Management, and IT Emergency Management with infrastructure expertise during incidents and post-incident hardening.

Infrastructure security

• Own the security architecture and baseline standards for the AI platforms we run internally: model gateways and self-hosted models, agent frameworks, assistant integrations, connectors, and retrieval pipelines over internal data.
• Define and enforce how agents are identified, authenticated, and authorized: non-human identity handling, credential and token management, least-privilege tool and system access, and where autonomous action requires a human in the loop.
• Establish what data internal AI systems may access and index, and ensure agent activity is logged, attributable, and reviewable to the standard our regulatory and certification obligations require.
• Run pre-deployment security reviews for new internal AI platforms and agent use cases, at a pace that fits how fast these are being adopted, and keep a picture of where unsanctioned AI usage is emerging.
• Advise the security functions and internal engineering teams on adopting AI safely, including the guardrails that make that adoption defensible.

• Hands-on experience deploying or securing internal AI platforms, agent frameworks, or tool-calling integrations in production.
• Familiarity with NIS2 / BSIG or ISO 27001
• Background in DNS, e-mail infrastructure, or abuse-adjacent platform security.
• Experience in a multi-brand or post-acquisition environment where the same control has to land in several different implementations.
• Security engineering or development background (automation, tooling, scripting).

Who fits

Someone comfortable being the only expert in the room on a given question, who prefers fixing root causes over filing findings, and who can operate across security functions and platform teams they do not control. You should be genuinely interested in AI systems as engineering artifacts, not just as a policy topic – much of this practice is still being written, and you will be writing ours.

Application Note

We value diversity and welcome all applications – regardless of, for example, gender, nationality, ethnic or social origin, religion, disability, age as well as sexual orientation and identity, physical characteristics, marital status or any other irrelevant factor subject to applicable law.