Kubernetes has exploded in popularity as the platform of choice for container orchestration, with over 90% of global organizations now running Kubernetes in production.
With great power comes great responsibility. The native role-based access control (RBAC) in Kubernetes grants immense flexibility to restrict user permissions through custom policies. However, complicated RBAC schemes are prone to dangerous misconfigurations that give attackers an open door.
According to a 2022 survey by Styra, 91% of Kubernetes production clusters had excessive permissions exposing them to security risks.
So if you‘ve built your shiny new Kubernetes cluster, it‘s absolutely vital to audit RBAC configuration. This guide will arm you with everything needed to find and fix risky permissions.
Here‘s what I‘ll cover:
- A Primer on Kubernetes RBAC
- Critical Risks of Faulty RBAC
- 10 Must-Know Tools to Audit RBAC
- 12 Tips for Securing RBAC Policies
- Workflows for Continuously Auditing RBAC
Let‘s get started by looking at how RBAC works in Kubernetes and why it‘s a frequent attack vector.
A Primer on Kubernetes RBAC
Role-based access control (RBAC) enables administrators to define granular permissions for users through assignment of roles.
The 4 key API objects that constitute RBAC in Kubernetes are:
Roles – Assign access within single namespaces
ClusterRoles – Assign cluster-wide permissions
RoleBindings – Bind roles to users/groups
ClusterRoleBindings – Bind clusterroles cluster-wide
For example, you can create a role called "developer" that allows reading pods in the dev namespace. Then map developers to this role with a rolebinding in that namespace.
RBAC prevents unfettered access and implements least privilege principles. But just like everything in security – improper implementation introduces risks.
Dangerous Implications of Faulty RBAC
Misconfigured RBAC policies open the doors for mayhem. Some examples of risky permissions include:
- Wildcard roles granting excessive privileges
- Stale roles not removed when employees leave
- Users self-escalating permissions
- Overprovisioned service accounts
- Confusing custom roles leading to errors
These faulty configurations defeat the purpose of RBAC and provide openings for attackers. Any compromised user or workload can cause immense damage if given enough privileges.
According to research by Aqua, 93% of Kubernetes clusters have high-risk RBAC issues like those above. And the clean up is manual and painful.
This glaring security gap is precisely why dedicated RBAC auditing is so crucial – to identify and revoke risky permissions before disaster strikes.
Next, let‘s explore 10 capable tools to audit Kubernetes RBAC.
Top 10 Tools to Audit Kubernetes RBAC
Manually reviewing RBAC is tedious and error-prone. Thankfully, specialized tools can automatically scan configurations and surface risks in seconds.
Here are the top 10 open source and commercial Kubernetes RBAC auditing tools:
| Tool | Description | Free |
|---|---|---|
| KubiScan | Scans RBAC configs for risks | Yes |
| Krane | RBAC analysis and visualization | Yes |
| RBAC Tool | Scans + RBAC policy generation | Yes |
| Fairwinds Insights | Policy-based RBAC auditing | 21-day trial |
| RoleIQ | Finds risky roles via analysis | No |
| Repokitteh | Highlights stale bindings | Yes |
| Rego Policy Library | ~200 pre-defined RBAC policies | Yes |
| Polar Audit | Observes live permission usage | No |
| kubectl-who-can | Permission simulation | Yes |
| Octarine kAudit | Kubernetes audit logging | No |
This diverse list contains both simple static analyzers and advanced behavioral tools well-suited for various needs.
For example, Repokitteh helped Shopify prune hundreds of unused stale roles across many clusters. RoleIQ uses continuous analysis to assign risk scores to roles based on excess privileges. Polar Audit witnesses live traffic to detect anomalies in permission consumption.
Make sure to choose a tool aligned with your use case – whether it‘s periodic auditing, CI/CD integration, or runtime detection. Most offer a free tier or trial to test drive before purchasing.
Next, let‘s switch gears and see how we can configure RBAC policies to minimize these risks in the first place.
12 Tips for Securing RBAC Policies
Garbage in, garbage out. Before diving into audits, RBAC policies themselves need to follow security best practices.
Here are 12 tips for creating least privilege policies to reduce attack surface:
1. Document all custom roles with clear descriptions
2. Assign namespace-specific roles whenever possible instead of cluster-wide
3. Avoid broad wildcard rules with verbs like ‘*‘
4. Define users, groups, service accounts for role mappings rather than ‘system:authenticated‘
5. Create separate policies for dev/staging/prod environments
6. Follow principle of least privilege for role creation
7. Prevent privilege escalation by restricting self-provisioning
8. Enforce policies blocking role modifications without approval
9. Prune unused stale roles older than X days with a job
10. Log all RBAC changes for auditing trails
11. Scan configs against CIS benchmarks using OPA Gatekeeper
12. Simulate policies prior to applying in clusters with tools like Rego
Adhering to these best practices will significantly reduce the blast radius from any subsequent attacks or misuse due to compromised credentials.
For example, Internet giant NetEase ran into outages after an engineer accidentally deleted crucial system roles. Following least privilege would have prevented such incidents.
Continuously Audit RBAC as Part of DevSecOps
Creating solid RBAC foundations is half the formula – continuous analysis completes it.
Here is a simple 4 step workflow to bake RBAC auditing into DevSecOps pipelines:
1. Scan RBAC with preferred tooling to catch policy changes
2. Feed results into CI/CD systems such as Argo or Spinnaker
3. Reject bad configs pre-deployment by integrating gates
4. Revoke/update violations automatically or trigger manual review
This automated process shifts RBAC auditing left to prevent vulnerabilities from ever reaching production. Air-gapped scanning can‘t prevent insider risks.
Advanced capabilities like anomaly detection of new user behavior also helps address permission creep or breaches.
Over time, mature RBAC analysis into a robust governance process including periodic manual verification of automatically blocked issues. Custom policies tailored to your environments also boost accuracy of tools.
Conclusion
In this comprehensive guide, we discussed:
- The implications of misconfigured Kubernetes RBAC policies
- 10 capable open source and commercial tools to audit RBAC
- 12 best practices for defining secure RBAC configurations
- Workflows to enable continuous RBAC auditing
With great power comes great responsibility. Kubernetes RBAC gives immense power to define precise access controls. Use it responsibly and continuously analyze policies before attackers exploit any openings.
I hope you enjoyed this guide! Please share any other tips or tools for locking down Kubernetes RBAC. Stay safe out there.
