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Falco is a CNCF-graduated runtime security tool that monitors Linux syscalls to detect 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.
Detects container escape attempts using Falco rules that monitor syscalls, host filesystem mounts, and privilege escalations in Kubernetes and Docker environments.
Detects container escape attempts using Falco runtime security rules in Kubernetes or Docker, monitoring syscalls, host filesystem mounts, nsenter, and privileged containers.
Detects container escape attempts in Docker/Kubernetes via Falco, eBPF syscall monitoring, auditd, and runtime security rules. For incident response and threat hunting.
Share bugs, ideas, or general feedback.
Falco is a CNCF-graduated runtime security tool that monitors Linux syscalls to detect 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.
# Add Falco Helm chart
helm repo add falcosecurity https://falcosecurity.github.io/charts
helm repo update
# Install Falco with eBPF driver
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
# Verify
kubectl get pods -n falco
kubectl logs -n falco -l app.kubernetes.io/name=falco --tail=20
# Add Falco GPG key and repo
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
# Start Falco
sudo systemctl enable falco
sudo systemctl start falco
- rule: Container Mounting Host Filesystem
desc: Detect 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: Nsenter Execution in Container
desc: Detect 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: Launch Privileged Container
desc: Detect 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: Write to Sysrq Trigger
desc: Detect 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: Container Loading Kernel Module
desc: Detect 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: Write to Cgroup Release Agent
desc: Detect 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: Container Reading Host Shadow File
desc: Detect 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: Container Accessing Docker Socket
desc: Detect 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]
# /etc/falco/rules.d/container-escape.yaml
- 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: Detect 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: Detect container access to 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]
# /etc/falco/falco.yaml (key settings)
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
# Falcosidekick values.yaml
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}}
# Simulate container escape attempt (in a test container)
kubectl run test-escape --image=alpine --restart=Never -- sh -c "cat /etc/shadow"
# Simulate nsenter
kubectl run test-nsenter --image=alpine --restart=Never --overrides='{"spec":{"hostPID":true}}' -- nsenter -t 1 -m -u -i -n -- cat /etc/hostname
# Check Falco alerts
kubectl logs -n falco -l app.kubernetes.io/name=falco --tail=50 | grep -i escape