Posts Tagged ‘K8S’
[KCD UK 2024] Deep Dive into Kubernetes Runtime Security
Saeid Bostandoust, founder of CubeDemi.io, delivered an in-depth presentation at KCDUK2024 on Kubernetes runtime security, focusing on tools and techniques to secure containers during execution. As a CNCF project contributor, Saeid explored Linux security features like Linux Capabilities, SELinux, AppArmor, Seccomp-BPF, and KubeArmor, providing a comprehensive overview of how these can be applied in Kubernetes to mitigate zero-day attacks and enforce policies. His talk emphasized practical implementation, observability, and policy enforcement, aligning with KCDUK2024’s focus on securing cloud-native environments.
Understanding Runtime Security
Saeid defined runtime security as protecting applications during execution, contrasting it with pre-runtime measures like static code analysis. Runtime security focuses on mitigating zero-day attacks and malicious behavior through real-time intrusion detection, process isolation, policy enforcement, and monitoring. Linux offers over 30 security mechanisms, including SELinux, AppArmor, Linux Capabilities, Seccomp-BPF, and namespaces, alongside kernel drivers to counter threats like Meltdown and Spectre. Saeid focused on well-known features, explaining their roles and Kubernetes integration.
Linux Capabilities: Historically, processes were either privileged (with full root permissions) or unprivileged, leading to vulnerabilities like privilege escalation via commands like ping. Linux Capabilities, introduced to granularly assign permissions, allow processes to perform specific actions (e.g., opening raw sockets for ping) without full root privileges. In Kubernetes, capabilities can be configured in pod manifests to drop unnecessary permissions, enhancing security even for root-run containers.
Seccomp-BPF: Seccomp (Secure Computing) restricts system calls a process can make. Originally limited to basic calls (read, write, exit), Seccomp-BPF extends this with customizable profiles. In Kubernetes, a Seccomp-BPF profile can be defined in a JSON file and applied via a pod’s security context, terminating processes that attempt unauthorized system calls. Saeid demonstrated a restrictive profile that limits a container to basic operations, preventing it from running if additional system calls are needed.
LSM Modules (AppArmor, SELinux, BPF-LSM): Linux Security Modules (LSM) provide hooks to intercept operations, such as file access or network communication. AppArmor uses path-based profiles, while SELinux employs label-based policies. BPF-LSM, a newer option, allows dynamic policy injection via eBPF code, offering flexibility without requiring application restarts. Saeid noted that BPF-LSM, available in kernel versions 5.7 and later, supports stacking with other LSMs, enhancing Kubernetes security.
KubeArmor: Simplifying Policy Enforcement
KubeArmor, a CNCF project, simplifies runtime security by allowing users to define policies via Kubernetes Custom Resource Definitions (CRDs). These policies are translated into AppArmor, SELinux, or BPF-LSM profiles, depending on the worker node’s LSM. KubeArmor addresses the challenge of syncing profiles across cluster nodes, automating deployment and updates. It uses eBPF for observability, monitoring system calls and generating telemetry for tools like Prometheus and Elasticsearch. Saeid showcased KubeArmor’s architecture, including a daemon set with an init container for compiling eBPF code and a relay server for aggregating logs and alerts.
An example policy demonstrated KubeArmor denying access to sensitive files (e.g., /etc/passwd, /etc/shadow) and commands (e.g., apt, apt-get), with logs showing enforcement details. Unlike manual AppArmor or SELinux profiles, which are complex and hard to scale, KubeArmor’s declarative approach and default deny policies simplify securing containers, preventing access to dangerous assets like /proc mounts.
Practical Implementation and Community Engagement
Saeid provided practical examples, such as configuring a pod to drop all capabilities except those needed, applying a Seccomp-BPF profile to restrict system calls, and using KubeArmor to enforce file access policies. He highlighted KubeArmor’s integration with tools like OPA Gatekeeper to block unauthorized commands (e.g., kubectl exec) when BPF-LSM is unavailable. For further learning, Saeid offered a 50% discount on CubeDemi.io’s container security workshop, encouraging KCDUK2024 attendees to deepen their Kubernetes security expertise.
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Hashtags: #Kubernetes #RuntimeSecurity #KubeArmor #CNCF #LinuxSecurity #SaeidBostandoust #KCDUK2024