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Scenario #213
Security
K8s v1.20, GKE
Misconfigured API Server Authentication Allowing External Access
API server authentication was misconfigured, allowing external unauthenticated users to access the Kubernetes API.
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What Happened
The Kubernetes API server was mistakenly exposed without authentication, allowing external users to query resources without any credentials.
Diagnosis Steps
- 1Examined the API server configuration and found that the authentication was set to allow unauthenticated access (--insecure-allow-any-token was enabled).
- 2Reviewed ingress controllers and firewall rules and confirmed that the API server was publicly accessible.
Root Cause
The API server was misconfigured to allow unauthenticated access, exposing the cluster to unauthorized requests.
Fix/Workaround
• Disabled unauthenticated access by removing --insecure-allow-any-token from the API server configuration.
• Configured proper authentication methods, such as client certificates or OAuth2.Lessons Learned
Always secure the Kubernetes API server and ensure proper authentication is in place to prevent unauthorized access.
How to Avoid
- 1Regularly audit the API server configuration to ensure proper authentication mechanisms are enabled.
- 2Use firewalls and access controls to limit access to the API server.