Mesh-Kridik : An Open-Source Security Checker That Performs Security Checks On A Kubernetes Cluster

Mesh-Kridik is an open-source security checker that performs various security checks on a Kubernetes cluster with istio service mesh and outputs a security report

The security checks tests are the full implementation of istio security best practices

The security checks performed on a Kubernetes cluster with istio service mesh and is leveraged by OPA (Open Policy Agent) to enforce security rules, and the output audit report includes: the root cause of the security issue and proposed remediation for the security issue.

Requirements

• Go 1.16+
• jq
• istio

Installation

git clone https://github.com/chen-keinan/mesh-kridik
cd mesh-kridik
make build

• ote: mesh-kridik require root user to be executed

Quick Start

Execute Mesh-Kridik without any flags , execute all tests

./mesh-kridik

Execute mesh-kridik with flags , execute test on demand

Usage: mesh-kridik [–version] [–help] []
Available commands are:
-r , –report : run security checks and generate remediation report
-i , –include: execute only specific security check, example -i=1.1
-e , –exclude: ignore specific security check, example -e=1.1,2.0

Execute tests and generate failure tests report and it remediation’s

./mesh-kridik -r

Istio Security Checks

Name	Description	Impact
Mutual TLS	Istio Mutual TLS proxies are configured in permissive mode by default	proxies will accept both mutual TLS and plaintext traffic
Istio Safer Authorization Policy Patterns	Use ALLOW-with-positive-matching or DENY-with-negative-match patterns	These authorization policy patterns are safer because the worst result in the case of policy mismatch is an unexpected 403 rejection instead of an authorization policy bypass.
path normalization in authorization policy	The enforcement point for authorization policies is the Envoy proxy instead of the usual resource access point in the backend application	A mismatch can lead to either unexpected rejection or a policy bypass
TLS origination for egress traffic	Use of DestinationRule on service ServiceEntry for egress traffic	Not using TLS origination for egress traffic to an external service will be send with plain/text
Protocol detection	explicitly declare the service protocol	miss detection may result in unexpected traffic behavior
CNI support	istio transparent traffic capture	not al net traffic will not be capture
overly broad hosts	avoid overly broad hosts settings in Gateway	may cause potential exposure of unexpected domains
Restrict Gateway creation privileges	restrict creation of Gateway resources to trusted cluster administrators	may cause creation of gateway by untrusted users
Configure a limit on downstream connections	Update global_downstream_max_connections in the config map according to the number of concurrent connections needed by individual gateway instances in your deployment. Once the limit is reached, Envoy will start rejecting tcp connections	no limit on the number of downstream connections can cause exploited by a malicious actor
Configure third party service account tokens	It is recommended to configure 3rd party tokens Because the properties of the first party token are less secure	first party token properties are less secure and might cause authentication breach
Control Plane	Istiod exposes a few unauthenticated plaintext ports for convenience by default	exposes the XDS service port 15010 and debug port 8080 over unauthenticated plaintext
Data Plane	The proxy exposes a variety of ports	The applications running in the same pod as the proxy have access; there is no trust boundary between the sidecar and application
Understand traffic capture limitations	Securing egress traffic by setting the meshConfig.outboundTrafficPolicy.mode	external service access will not be controlled

User Plugin Usage (via go plugins)

The Kube-kridik expose a hook for user plugins Example :

• MeshSecurityCheckResultHook – this hook accepts k8s service mesh security checks results

Compile user plugin

go build -buildmode=plugin -o=~//.so ~//.go

Copy plugin to folder (.kube-kridik folder is created on the 1st startup)

cp ~//.so ~/.kube-kridik/plugins/compile/.so