Ship of Fools: Shoring Up Kubernetes Security

Hackers gonna hack. They have their own motivations, and they don’t care about your constraints. As attackers, they want to find vulnerabilities and exploit them. As a defender, your mission is to stop them. Mistakes can be easy to make, but with the right configuration and attention to security best practices many attacks can be prevented.

This talk will give you practical advice about securing your Kubernetes clusters, from an attacker’s perspective. We’ll walk through the attack process from discovery to post-exploitation, and you’ll walk away with tools and techniques that can be used for prevention along the way. Learn how to keep your infrastructure safer by making a hacker’s job harder.

Transcript

1. SHIP OF FOOLS
   Shoring Up Kubernetes Security
   @IanColdwater
   

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2. WHO AM I?
   My name is Ian Coldwater.
   I do DevSecOps at Jamf Software, where I
   focus on container security and hardening
   cloud infrastructure.
   I’m also an ethical hacker.
   @IanColdwater
   

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3. AS AN ATTACKER, I WANT TO PWN YOU.
   @IanColdwater
   

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4. WHAT'S A CONTAINER?
   @IanColdwater
   

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5. WHAT IS KUBERNETES?
   • Kubernetes is an open-source system for automating deployment, scaling, and
   management of containerized applications. It groups containers that make up an
   application into logical units for easy management and discovery.
   @IanColdwater
   

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6. @IanColdwater
   

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7. @IanColdwater
   

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8. EVEN HACKERS AREN'T IMMUNE TO THIS
   @IanColdwater https://hackernoon.com/capturing-all-the-flags-in-bsidessf-ctf-by-pwning-our-infrastructure-3570b99b4dd0
   

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9. SOME CONSIDERATIONS
   • Kubernetes has a very active community of contributors who are pushing changes very
   quickly. Security features have vastly improved in the last several releases.
   • Older Kubernetes releases are still commonly found in production, and left a lot wide
   open by default.
   • Attack and defense can vary with individual configurations.
   @IanColdwater
   

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10. GOOD NEWS AND BAD NEWS
    • It is possible to secure your Kubernetes cluster.
    • It's probably not going to come that way by default.
    • Security doesn't end there.
    @IanColdwater
    

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12. @IanColdwater
    

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13. WHAT IS YOUR THREAT MODEL?
    • What are you trying to protect?
    • Who are you trying to protect it from?
    • What capabilities do your adversaries have?
    • What capabilities do you have to defend against them?
    @IanColdwater
    

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14. KUBERNETES THREAT MODEL
    • External attacker
    • Application or container compromise
    • Compromised user or credentials
    @IanColdwater
    

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15. AN ATTACKER'S WORKFLOW
    • Discovery
    • Enumeration
    • Getting In
    • Post-Exploitation
    • Exfiltration
    • Privilege Escalation
    • Lateral Movement
    • Persistence?
    • Rinse and Repeat
    @IanColdwater
    

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16. EXTERNALLY VISIBLE PORTS
    • 2379/tcp open | etcd
    • 4194/tcp open | cAdvisor
    • 443/tcp open | API Server (sometimes this is port 6443 or 8443)
    • 8080/tcp open | Insecure API Server
    • 10250/tcp open | kubelet
    • 10255/tcp open | kubelet (read only)
    • ???/open | various network plugins
    @IanColdwater
    

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17. @IanColdwater
    

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18. PREVENTING EXTERNAL ATTACKERS
    • Don't leave your ports open if you don't have to
    • Make sure that all management ports that are visible externally require authentication
    • Limit SSH access to Kubernetes nodes
    @IanColdwater
    

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19. DEFENDERS THINK IN LISTS.
    ATTACKERS THINK IN GRAPHS.
    What’s in your graph?
    19
    @IanColdwater
    

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20. USER OR CREDENTIAL COMPROMISE
    @IanColdwater
    

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21. PREVENTING USER COMPROMISE
    • Don’t fall for social engineering!
    • Keep credentials encrypted and limit access to them.
    @IanColdwater
    

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22. CONTAINER COMPROMISE
    @IanColdwater
    

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23. KUBERNETES CONTROL PLANE
    @IanColdwater
    

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24. CONTAINER BREAKOUTS
    shit just got real
    @IanColdwater
    

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25. PREVENTING CONTAINER COMPROMISE
    • Write your own applications as securely as possible.
    • Treat other people’s code with caution!
    • Run static code analysis on your applications and containers to check for vulnerabilities.
    You can use open source tools for this such as Clair by CoreOS.
    • If you find vulnerabilities, patch or mitigate them.
    @IanColdwater
    

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26. DEFENSE IN DEPTH
    • Reduce your attack surface
    • Limit your blast radius
    @IanColdwater
    

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27. PRINCIPLE OF LEAST PRIVILEGE
    @IanColdwater
    

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28. CONTROLS
    • Network Policies
    • Admission Controllers
    • Role-Based Access Control
    • Pod Security Policies
    • Resource Quotas
    • Logging and Monitoring
    @IanColdwater
    

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29. GENERAL RECOMMENDATIONS
    • If you can upgrade, upgrade. If you can’t upgrade, mitigate.
    • Secure defaults are very important!
    • Be careful with your secrets
    • Log and monitor…outside your cluster.
    @IanColdwater
    

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30. TL;DR
    • A lot of this is standard security advice.
    • Practice good cyber hygiene, and get the basics right!
    @IanColdwater
    

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31. YOU GOT THIS!
    I believe in you!
    @IanColdwater
    

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32. RESOURCES
    • securing your cluster - goo.gl/gE9sj6
    • hacking and hardening kubernetes by
    example - goo.gl/QJhsDb
    • a hacker's guide to kubernetes and the cloud
    - goo.gl/CZgG6V
    • preventing attacks at scale - goo.gl/Y7EeU7
    • shipping in pirate-infested waters - 

    goo.gl/TRwXCu
    • CIS benchmarks - goo.gl/v2ZWXR
    • lessons from the cryptojacking attack at tesla -
    goo.gl/u4ucvo
    • analysis of a kubernetes hack - goo.gl/VKteVq
    • attackers think in graphs - goo.gl/imExzC
    • github.com/kelseyhightower/nocode - the
    best way to write secure and reliable
    applications!
    @IanColdwater
    

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