By default, Kubernetes allows the addition of Linux capabilities to containers. While these capabilities can enhance container functionality, they also pose significant security risks if not properly controlled. Privileged processes within containers can lead to:
Unauthorized Port Access: The CAP_NET_BIND_SERVICE capability allows containers to bind to privileged ports (below 1024). If an attacker gains access to this capability, they could expose the cluster to external threats by opening privileged ports, leading to potential unauthorized access and attacks.
Escalation of Privileges: Containers running with elevated privileges can exploit vulnerabilities to gain control over the cluster. This could result in unauthorized data access, disruption of services, or control over other containers in the cluster.
Network Manipulation: Capabilities like CAP_NET_RAW allow containers to manipulate network traffic. This could enable attackers to perform man-in-the-middle attacks, intercept traffic, or conduct unauthorized network scans, posing a significant risk to the cluster's network security.
To mitigate these risks, it's crucial to limit the addition of privileged capabilities in containers.
