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Harden Your
Kubernetes Cluster

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Hello!
I am smalltown
Maicoin Site Reliability Engineer
Taipei HashiCorp UG Organizer
AWS UG Taiwan Staff
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Network RuntimeImage Credential PaC
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Network RuntimeImage Credential PaC
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Image Build Practice (1/2)
◎ Minimal Base Images
◎ Least Privileged User
◎ Use Fixed Tags
◎ Sign/Verify Images (Docker Notary)
◎ Don’t Contain Sensitive Information
Ref

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Image Build Practice (2/2)
◎ Use COPY Instead of ADD
◎ Use Metadata Labels
◎ Multi-Stage Build Small/Secure Images
◎ Use Linter (hadolint)
◎ Find/Fix/Monitor Vulnerabilities
Ref

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How to Find Vulnerabilities?
◎ Of Course! Scanning!
◎ Commercial V.S. Open Source
◎ Open Source: Anchor, Clair, Trivy...
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Scan Coverage
◎ OS Packages
○ Alpine, Red Hat Universal Base Image, Red Hat
Enterprise Linux, CentOS, Debian and Ubuntu
◎ Application Dependencies
○ Bundler, Composer, Pipenv, Poetry, npm, yarn and
Cargo
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Try to Use It! (1/2)
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~$ docker run --rm -v $HOME/Library/Caches:/root/.cache/ aquasec/trivy
python:alpine3.10

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Try to Use It! (2/2)
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~$ docker run --rm -v $HOME/Library/Caches:/root/.cache/ aquasec/trivy
golang:1.12.9-buster

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DevSecOps
◎ Integrate with CI/CD Framework, e.g. if Find
Critical Vulnerability then Fail the Pipeline
◎ Don’t Forget Store the Vulnerability
Database/Data
◎ Use Json Format Output to Generate
Report
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Competitive Analysis
Ref

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Regular Vulnerability Assessment
◎ Process of Defining, Identifying, Classifying
and Prioritizing Vulnerabilities
◎ Information on the Security Weaknesses in
its environment
◎ Assess the Risks Associated with those
Weaknesses and Evolving Threats
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Network RuntimeImage Credential PaC
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Kubernetes Secret
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Ref

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HashiCorp Vault
◎ Secures, stores, and tightly controls access
to tokens, passwords, certificates, API keys
◎ Handles leasing, key revocation, key rolling,
and auditing
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Ideal Credential Lifecycle
Service is Accessed
Application
1. Request Access Credential (Running)
2. Use the Credential to Access Service
3. Revoke the Credential
Credentials Only
Exist in Memory
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Authentication
◎ Vault provide various auth method
○ Tokens, AppRole
○ AWS, Azure, Google Cloud
○ LDAP, GitHub ...etc
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Authorization
◎ Vault store credentials like key/value DB, e.g.
○ /secret/stag/database/admin
○ /secret/prod/database/admin
◎ Hence, predefined policy grant appropriate
permission, e.g.
path "secret/stag/database/admin" {
capabilities = ["read"]
} 21

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Dynamic Credentials
◎ Vault support many secret backend
○ AWS, Azure, GCP, Database...etc
◎ Take database for example, you could generate
dynamic database credentials
$ vault read database/creds/my-role
Key Value
--- -----
lease_duration 1h
password 8cab931c-d62e-a73d-60d3-5ee85139cd66
username v-root-e2978cd0- 22

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HashiCorp Vault Workshop：幫
Credentials 找個窩
◎ Slide: Here
◎ GitHub: Here
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Network RuntimeImage Credential PaC
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Connection Between Pods/Endpoints
Out In Internet
- Port
- IP, FQDN
- Protocol
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What is The Problem?
◎ By Default, Pods are Non-Isolated; They
Accept Traffic from any Source.
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Kubernetes Network Policy
podSelector
Ref
- podSelector
- namespaceSelector
- ipBlock
- podSelector
- namespaceSelector
- ipBlock
Ingress (From)
Egress(To)
Protocol
Port

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How to Enable Network Policy
Ref

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Connection Between Pods/Endpoints
Out In Internet
- Port
- IP, FQDN
- Protocol
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What is The Problem?
◎ MITM (Man-In-The-Middle Attack)
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Istio
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Istio with Mutual TLS
Ref

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Policy & DestinationRule
Ref

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Istio with Kiali
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Network RuntimeImage Credential PaC
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Runtime Security Tools
Enforcement
Auditing
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Enforcement Runtime Security Tools
◎ Using the Policy to Change the Behavior of
a Process by Preventing System Calls from
Succeeding
○ Pod Security Policy
○ AppArmor
○ Seccomp
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Pod Security Policies
◎ Define a Set of Conditions that a Pod Must
Run With in Order to be Accepted Into the
System
○ Usage of volume types
○ Usage of host networking and ports
○ The user and group IDs of the container
○ ... Ref

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How to Use PSP
(Cluster)Role
(Cluster)RoleBinding For Pod
For Deployment, ...
Create
Use
With
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When a Pod Created...
◎ The PSP is Enabled, Pod Don’t Use the PSP
-> Fail
◎ The PSP is Enabled, Pod Can Use the PSP,
Pod Don’t Follow PSP -> Fail
◎ The PSP is Enabled, Pod Can Use the PSP,
Pod Follow PSP -> Success
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Auditing Runtime Security Tools
◎ Using the Policy to Monitor the Behavior of
a Process and Notify when its behavior
steps outside the policy
○ Falco
○ Auditd
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Falco
◎ A Behavioral Activity Monitor Designed to
Detect Anomalous Activity in Your
Applications
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How Falco Take Effect
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Falco Rules
- macro: access_file
condition: evt.type=open
- rule: program_accesses_file
desc: track whenever a set of programs opens a file
condition: proc.name in (cat, ls) and (access_file)
output: a tracked program opened a file (user=%user.name
command=%proc.cmdline file=%fd.name)
priority: INFO
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Falco V.S. Others
Falco Others
User Space Kernel Level
Kill/Suspend/Starve the Falco
Process
Replacing a loaded set of
policies or BPF program in the
kernel is probably more difficult
Much Richer Set of Information
Powering Its Policies
Those Types of Policies are
More Difficult to Implement at
the Kernel Level
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Network RuntimeImage Credential PaC
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Policy as Code
YAML Engineer 4NI ?!
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Open Policy Agent
◎ A general-purpose Policy Engine that Helps Solve Use
Cases Ranging From Authorization and Admission
Control to Resource Placement.
○ Kubernetes Admission Control
○ HTTP API Authorization
○ Remote Access
○ Data Filtering with Partial Evaluation
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OPA Flow
ContextPolicy
API Authorization
API
Retrieve Data from Target Service
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Finally Not YAML
◎ Rego was Inspired by Datalog, Which is a
Well Understood, Decades Old Query
Language
◎ Rego Queries are Assertions on Data Stored
in OPA
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Ref

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Rego Sample Code
package kubernetes.admission
import data.kubernetes.namespaces
deny[msg] {
input.request.kind.kind == "Ingress"
input.request.operation == "CREATE"
host := input.request.object.spec.rules[_].host
not fqdn_matches_any(host, valid_ingress_hosts)
msg := sprintf("invalid ingress host %q", [host])
} Ref

52.
Thanks!
Any questions?
You can find me at:
facebook.com/smalltown0110
smalltown@awsug.tw
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53.
We’re Hiring!!
Software Engineer in
Test
Software Engineer
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