undermybelt Implementing Runtime Security with Tetragon
Overview
Tetragon is a CNCF project under Cilium that provides flexible Kubernetes-aware security observability and runtime enforcement using eBPF. By operating at the Linux kernel level, Tetragon can monitor and enforce policies on process execution, file access, network connections, and system calls with less than 1% performance overhead -- far more efficient than traditional user-space security agents.
When to Use
- When deploying or configuring implementing runtime security with tetragon capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Prerequisites
- Kubernetes cluster v1.24+ with Helm 3.x installed
- Linux kernel 5.4+ (5.10+ recommended for full eBPF feature support)
- kubectl access with cluster-admin privileges
- Familiarity with eBPF concepts and Kubernetes security primitives
Core Concepts
eBPF-Based Security
Tetragon attaches eBPF programs directly to kernel functions, enabling:
- Process lifecycle tracking: Monitor every process creation, execution, and termination across all pods
- File integrity monitoring: Detect unauthorized reads/writes to sensitive files
- Network observability: Track all TCP/UDP connections with full pod context
- System call filtering: Enforce policies on dangerous syscalls like ptrace, mount, or unshare
TracingPolicy Custom Resources
Tetragon uses TracingPolicy CRDs to define what kernel events to observe and what actions to take:
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
name: detect-privilege-escalation
spec:
kprobes:
- call: "security_bprm_check"
syscall: false
args:
- index: 0
type: "linux_binprm"
selectors:
- matchBinaries:
- operator: "In"
values:
- "/bin/su"
- "/usr/bin/sudo"
- "/usr/bin/passwd"
matchNamespaces:
- namespace: Pid
operator: NotIn
values:
- "host_ns"
matchActions:
- action: Post
Enforcement Actions
Tetragon can take three types of actions directly in the kernel:
- Sigkill: Immediately terminate the offending process
- Signal: Send a configurable signal to the process
- Override: Override the return value of a kernel function to deny an operation
Installation and Configuration
Step 1: Install Tetragon with Helm
helm repo add cilium https://helm.cilium.io
helm repo update
helm install tetragon cilium/tetragon \
--namespace kube-system \
--set tetragon.enableProcessCred=true \
--set tetragon.enableProcessNs=true \
--set tetragon.grpc.address="localhost:54321"
Step 2: Install the Tetragon CLI
GOOS=$(go env GOOS)
GOARCH=$(go env GOARCH)
curl -L --remote-name-all \
https://github.com/cilium/tetragon/releases/latest/download/tetra-${GOOS}-${GOARCH}.tar.gz
tar -xzvf tetra-${GOOS}-${GOARCH}.tar.gz
sudo install tetra /usr/local/bin/
Step 3: Verify Installation
kubectl get pods -n kube-system -l app.kubernetes.io/name=tetragon
tetra status
Practical Implementation
Detecting Container Escape Attempts
Create a TracingPolicy to detect processes attempting to escape container namespaces:
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
name: detect-container-escape
spec:
kprobes:
- call: "__x64_sys_setns"
syscall: true
args:
- index: 0
type: "int"
- index: 1
type: "int"
selectors:
- matchNamespaces:
- namespace: Pid
operator: NotIn
values:
- "host_ns"
matchActions:
- action: Sigkill
Monitoring Sensitive File Access
Detect reads of sensitive credentials:
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
name: monitor-sensitive-files
spec:
kprobes:
- call: "security_file_open"
syscall: false
args:
- index: 0
type: "file"
selectors:
- matchArgs:
- index: 0
operator: "Prefix"
values:
- "/etc/shadow"
- "/etc/kubernetes/pki"
- "/var/run/secrets/kubernetes.io"
matchActions:
- action: Post
Blocking Crypto-Miner Execution
Prevent known crypto-mining binaries from executing:
apiVersion: cilium.io/v1alpha1
kind: TracingPolicy
metadata:
name: block-cryptominers
spec:
kprobes:
- call: "security_bprm_check"
syscall: false
args:
- index: 0
type: "linux_binprm"
selectors:
- matchBinaries:
- operator: "In"
values:
- "/usr/bin/xmrig"
- "/tmp/xmrig"
- "/usr/bin/minerd"
matchActions:
- action: Sigkill
Observing Events with Tetra CLI
Stream runtime events in real-time:
# Watch all process execution events
kubectl exec -n kube-system ds/tetragon -c tetragon -- \
tetra getevents -o compact --process-only
# Filter events for a specific namespace
kubectl exec -n kube-system ds/tetragon -c tetragon -- \
tetra getevents -o compact --namespace production
# Export events in JSON for SIEM integration
kubectl exec -n kube-system ds/tetragon -c tetragon -- \
tetra getevents -o json | tee /var/log/tetragon-events.json
Integration with SIEM and Alerting
Export to Elasticsearch
# tetragon-helm-values.yaml
export:
stdout:
enabledCommand: true
enabledArgs: true
filenames:
- /var/log/tetragon/tetragon.log
elasticsearch:
enabled: true
url: "https://elasticsearch.monitoring:9200"
index: "tetragon-events"
Prometheus Metrics
Tetragon exposes metrics at :2112/metrics:
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
name: tetragon-metrics
namespace: kube-system
spec:
selector:
matchLabels:
app.kubernetes.io/name: tetragon
endpoints:
- port: metrics
interval: 15s
Key Metrics and Alerts
| Metric | Description | Alert Threshold |
|---|---|---|
tetragon_events_total |
Total security events observed | Spike > 3x baseline |
tetragon_policy_events_total |
Events matching TracingPolicies | Any Sigkill action |
tetragon_process_exec_total |
Process executions tracked | Anomalous new binaries |
tetragon_missed_events_total |
Dropped events due to buffer overflow | > 0 sustained |