Detection Container Escape with Falco Rules

Genel Bakış

Falco is a CNCF-graduated runtime security tool that monitors Linux syscalls to tespit etme
anomalous container behavior. It uses a rules engine to identify container escape techniques such as mounting host filesystems, accessing sensitive host paths, loading kernel modules, and exploiting privileged container capabilities.

Ne Zaman Kullanılır

• investigating yaparken security incidents that require Tespit etme container escape with falco rules
• building yaparken Tespit rules or threat hunting queries for this domain
• SOC yaparken: analysts need structured procedures for this analysis type
• validating yaparken security monitoring coverage for related attack techniques

Ön Gereksinimler

• Linux host with kernel 5.8+ (for eBPF driver) or kernel module support
• Kubernetes cluster (v1.24+) or standalone Docker/containerd
• Helm 3 for Kubernetes Dağıt:ment
• Root or privileged access for driver installation

Installing Falco

Kubernetes Dağıt:ment with Helm

helm repo add falcosecurity https://falcosecurity.github.io/charts
helm repo update

helm install falco falcosecurity/falco \
  --namespace falco --create-namespace \
  --set falcosidekick.enabled=true \
  --set falcosidekick.webui.enabled=true \
  --set driver.kind=ebpf \
  --set collectors.containerd.enabled=true \
  --set collectors.containerd.socket=/run/containerd/containerd.sock

kubectl get pods -n falco
kubectl logs -n falco -l app.kubernetes.io/name=falco --tail=20

Standalone Installation (Debian/Ubuntu)

curl -fsSL https://falco.org/repo/falcosecurity-packages.asc | \
  sudo gpg --dearmor -o /usr/share/keyrings/falco-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/falco-archive-keyring.gpg] https://download.falco.org/packages/deb stable main" | \
  sudo tee /etc/apt/sources.list.d/falcosecurity.list

sudo apt-get update
sudo apt-get install -y falco

sudo systemctl enable falco
sudo systemctl start falco

Container Escape Detection Rules

Rule 1: tespit etme
Host Mount from Container

- rule: Container Mounting Host Filesystem
  desc: tespit etme
a container attempting to mount the host filesystem
  condition: >
    spawned_process and container and
    proc.name = mount and
    (proc.args contains "/host" or proc.args contains "nsenter")
  output: >
    Container mounting host filesystem
    (user=%user.name container_id=%container.id container_name=%container.name
     image=%container.image.repository command=%proc.cmdline %evt.args)
  priority: CRITICAL
  tags: [container, escape, T1611]

Rule 2: tespit etme
nsenter Usage (Namespace Escape)

- rule: Nsenter Execution in Container
  desc: tespit etme
nsenter being used to escape container namespaces
  condition: >
    spawned_process and container and proc.name = nsenter
  output: >
    nsenter executed in container - potential escape attempt
    (user=%user.name container_id=%container.id image=%container.image.repository
     command=%proc.cmdline parent=%proc.pname)
  priority: CRITICAL
  tags: [container, escape, namespace, T1611]

Rule 3: tespit etme
Privileged Container Launch

- rule: Launch Privileged Container
  desc: tespit etme
a privileged container being launched
  condition: >
    container_started and container and container.privileged=true
  output: >
    Privileged container started
    (user=%user.name container_id=%container.id container_name=%container.name
     image=%container.image.repository)
  priority: WARNING
  tags: [container, privileged, T1610]

Rule 4: tespit etme
/proc/sysrq-trigger Write

- rule: Write to Sysrq Trigger
  desc: tespit etme
writes to /proc/sysrq-trigger which can crash or control the host
  condition: >
    open_write and container and fd.name = /proc/sysrq-trigger
  output: >
    Write to /proc/sysrq-trigger from container
    (user=%user.name container_id=%container.id image=%container.image.repository
     command=%proc.cmdline)
  priority: CRITICAL
  tags: [container, escape, host-manipulation]

Rule 5: tespit etme
Kernel Module Loading from Container

- rule: Container Loading Kernel Module
  desc: tespit etme
a container attempting to load a kernel module
  condition: >
    spawned_process and container and
    (proc.name in (insmod, modprobe) or
     (proc.name = init_module))
  output: >
    Kernel module loading from container
    (user=%user.name container_id=%container.id image=%container.image.repository
     command=%proc.cmdline)
  priority: CRITICAL
  tags: [container, escape, kernel, T1611]

Rule 6: tespit etme
Container Breakout via cgroups

- rule: Write to Cgroup Release Agent
  desc: tespit etme
writes to cgroup release_agent which is a known container escape vector
  condition: >
    open_write and container and
    fd.name endswith release_agent
  output: >
    Container writing to cgroup release_agent - escape attempt
    (user=%user.name container_id=%container.id image=%container.image.repository
     file=%fd.name command=%proc.cmdline)
  priority: CRITICAL
  tags: [container, escape, cgroup, CVE-2022-0492]

Rule 7: tespit etme
Erişim: Host /etc/shadow

- rule: Container Reading Host Shadow File
  desc: tespit etme
a container reading /etc/shadow on the host via mounted volume
  condition: >
    open_read and container and
    (fd.name = /etc/shadow or fd.name startswith /host/etc/shadow)
  output: >
    Container reading host shadow file
    (user=%user.name container_id=%container.id image=%container.image.repository
     file=%fd.name command=%proc.cmdline)
  priority: CRITICAL
  tags: [container, credential-access, T1003]

Rule 8: tespit etme
Docker Socket Access

- rule: Container Accessing Docker Socket
  desc: tespit etme
a container accessing the Docker socket which allows host control
  condition: >
    (open_read or open_write) and container and
    fd.name = /var/run/docker.sock
  output: >
    Container accessing Docker socket
    (user=%user.name container_id=%container.id image=%container.image.repository
     command=%proc.cmdline)
  priority: CRITICAL
  tags: [container, escape, docker-socket, T1610]

Complete Custom Rules File

- list: escape_binaries
  items: [nsenter, chroot, unshare, mount, umount, pivot_root]

- macro: container_escape_attempt
  condition: >
    spawned_process and container and
    proc.name in (escape_binaries)

- rule: Container Escape Binary Execution
  desc: tespit etme
execution of binaries commonly used for container escape
  condition: container_escape_attempt
  output: >
    Escape-related binary executed in container
    (user=%user.name container=%container.name image=%container.image.repository
     command=%proc.cmdline parent=%proc.pname pid=%proc.pid)
  priority: CRITICAL
  tags: [container, escape, mitre_T1611]

- rule: Sensitive File Access from Container
  desc: tespit etme
container Erişim: sensitive host files
  condition: >
    (open_read or open_write) and container and
    (fd.name startswith /proc/1/ or
     fd.name = /etc/shadow or
     fd.name = /etc/kubernetes/admin.conf or
     fd.name startswith /var/lib/kubelet/)
  output: >
    Sensitive file accessed from container
    (container=%container.name image=%container.image.repository
     file=%fd.name command=%proc.cmdline user=%user.name)
  priority: CRITICAL
  tags: [container, sensitive-file, mitre_T1005]

Falco Configuration

rules_files:
  - /etc/falco/falco_rules.yaml
  - /etc/falco/rules.d/container-escape.yaml

json_output: true
json_include_output_property: true
json_include_tags_property: true

log_stderr: true
log_syslog: true
log_level: info

priority: WARNING

stdout_output:
  enabled: true

syslog_output:
  enabled: true

http_output:
  enabled: true
  url: http://falcosidekick:2801
  insecure: true

grpc:
  enabled: true
  bind_address: "unix:///run/falco/falco.sock"
  threadiness: 8

grpc_output:
  enabled: true

Alert Integration

Forward to Slack via Falcosidekick

config:
  slack:
    webhookurl: "https://hooks.slack.com/services/XXXXX"
    minimumpriority: "warning"
    messageformat: |
      *{{.Priority}}* - {{.Rule}}
      Container: {{.OutputFields.container_name}}
      Image: {{.OutputFields.container_image_repository}}
      Command: {{.OutputFields.proc_cmdline}}

Test Rules

kubectl run test-escape --image=alpine --restart=Never -- sh -c "cat /etc/shadow"

kubectl run test-nsenter --image=alpine --restart=Never --overrides='{"spec":{"hostPID":true}}' -- nsenter -t 1 -m -u -i -n -- cat /etc/hostname

kubectl logs -n falco -l app.kubernetes.io/name=falco --tail=50 | grep -i escape

En İyi Uygulamalar

1. Dağıt: Falco as DaemonSet to ensure coverage on all nodes
2. Use eBPF driver over kernel module for safer operation
3. Start with default rules (maturity_stable) then add custom rules
4. Forward alerts to SIEM/SOAR via Falcosidekick
5. Tag rules with MITRE ATT&CK technique IDs for correlation
6. Test rules in permissive mode before enforcing
7. Tune false positives by adding exception lists for known good processes
8. Monitor Falco health with Prometheus metrics endpoint

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