This is an German blog post as it is a recap from a German conference.
Sven und ich hatten zwei unglaublich spannende und lehrreiche Tage bei der heise devSec in Marburg.
Besonders hängen geblieben ist bei uns die Keynote von Volodymyr Styran zum Thema “Predictability Is Vulnerability: What Four Years of Cyber War Teach About Software Security”. Eine Erkenntnis daraus deckt sich stark mit unseren Erfahrungen aus zahlreichen Pentests: Angriffe müssen nicht immer aus einer hochkomplexen Exploit Chain bestehen. Oft sind es nicht die Zero-Day Exploit, die zur kritischen Kompromittierung der Umgebung führen würden, sondern banale Konfigurationsprobleme, wie schwache oder geleakte Credentials. Seine Erkenntnis ist, dass durch vorhersehbare Umgebungen, stabile Konfigurationen und kompromittierte Credentials die Angreifer lange unentdeckt und persistent bleiben und sich bewegen können.
In our presentation, we explored the security challenges of namespace-based multi-tenancy in Kubernetes. We demonstrated real-world attacks against Kubeflow, Istio, and Traefik that can break the intended isolation between namespaces and workloads. One of the highlights was demonstrating a privilege-escalation attack we discovered that allowed us to gain cluster-admin privileges.
This page introduces our structured methodology for assessing security risks in
Kubernetes environments that use Namespace-based Multi-Tenancy. It addresses
weaknesses that break Namespace-based isolation that not well studied, yet. We
found this issues during our research and presented them together with this
methodology in our
Talk at KubeCon + CloudNativeCon Europe 2026.
The methodology assumes that industry best practices, such as NetworkPolicies,
Role-Based Access Control (RBAC), and Pod Security Standards, are already in
place. These measures provide a necessary baseline level of protection against
well-known isolation threats. However, they are insufficient to address a class
of more subtle attack vectors arising from interactions between tenants and
shared components. Such attack vectors may still compromise the confidentiality,
integrity, and availability (CIA) of the cluster and its workloads, even in
well-hardened environments.
We reported a possible Man-in-the-Middle (MitM) attack scenario in which
a VirtualService can redirect or intercept traffic within the service mesh.
This affects Namespace-based Multi-Tenancy clusters where tenants have the
permissions to deploy Istio resources (networking.istio.io/v1).
This blog post highlights the risks of using Istio in multi-tenant clusters and
explains how users can mitigate these risks and safely operate Istio in their
deployments.