ReddRadar
Agent skill
detecting-container-escape-attempts
Container escape is a critical attack technique where an adversary breaks out of container isolation to access the host system or other containers. Detection involves monitoring for escape indicators
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SKILL.md
Detecting Container Escape Attempts
Overview
Container escape is a critical attack technique where an adversary breaks out of container isolation to access the host system or other containers. Detection involves monitoring for escape indicators such as namespace manipulation, capability abuse, kernel exploits, mounted sensitive paths, and anomalous syscall patterns using runtime security tools like Falco, Sysdig, and custom seccomp/audit rules.
When to Use
- When investigating security incidents that require detecting container escape attempts
- When building detection rules or threat hunting queries for this domain
- When SOC analysts need structured procedures for this analysis type
- When validating security monitoring coverage for related attack techniques
Prerequisites
- Linux host with kernel 5.10+ (eBPF support)
- Falco 0.37+ installed (kernel module or eBPF probe)
- Docker Engine or containerd runtime
- auditd configured
- Root access for eBPF/kernel module loading
Core Concepts
Common Container Escape Vectors
| Vector | Technique | MITRE ID |
|---|---|---|
| Privileged containers | Mount host filesystem, load kernel modules | T1611 |
| Docker socket mount | Create privileged container from within | T1610 |
| Kernel exploits | CVE-2022-0185 (fsconfig), Dirty Pipe, runc CVEs | T1068 |
| Capability abuse | CAP_SYS_ADMIN, CAP_SYS_PTRACE, CAP_NET_ADMIN | T1548 |
| Sensitive mounts | /proc/sysrq-trigger, /proc/kcore, cgroup release_agent | T1611 |
| Namespace escape | nsenter, unshare to host namespaces | T1611 |
| Symlink/bind mount | Escape through /proc/self/root | T1611 |
Detection Layers
- Syscall monitoring - eBPF/kernel module captures syscalls in real-time
- File integrity - Detect modification of escape-enabling paths
- Process monitoring - Track process creation, namespace changes
- Network monitoring - Detect container-to-host connections
- Audit logging - Linux auditd for capability and mount operations
Workflow
Step 1: Deploy Falco for Runtime Detection
# falco-values.yaml for Helm deployment
falco:
driver:
kind: ebpf # or modern_ebpf for kernel 5.8+
rules_files:
- /etc/falco/falco_rules.yaml
- /etc/falco/falco_rules.local.yaml
- /etc/falco/rules.d
json_output: true
json_include_output_property: true
http_output:
enabled: true
url: "http://falcosidekick:2801"
grpc:
enabled: true
priority: warning
# Install Falco via Helm
helm repo add falcosecurity https://falcosecurity.github.io/charts
helm install falco falcosecurity/falco \
--namespace falco-system --create-namespace \
-f falco-values.yaml
Step 2: Custom Falco Rules for Escape Detection
# /etc/falco/rules.d/container_escape.yaml
# Detect container escape via privileged container
- rule: Container Escape via Privileged Mode
desc: Detect attempts to escape container using privileged capabilities
condition: >
spawned_process and container and
(proc.name in (nsenter, unshare, mount, umount, modprobe, insmod) or
(proc.name = chroot and proc.args contains "/host"))
output: >
Container escape attempt via privileged operation
(user=%user.name container=%container.name image=%container.image.repository
command=%proc.cmdline pid=%proc.pid %container.info)
priority: CRITICAL
tags: [container, escape, T1611]
# Detect Docker socket access from container
- rule: Container Access to Docker Socket
desc: Detect container reading/writing to Docker socket
condition: >
(open_read or open_write) and container and
fd.name = /var/run/docker.sock
output: >
Docker socket accessed from container
(user=%user.name container=%container.name image=%container.image.repository
fd=%fd.name command=%proc.cmdline %container.info)
priority: CRITICAL
tags: [container, escape, docker_socket]
# Detect sensitive proc filesystem access
- rule: Container Access to Sensitive Proc Paths
desc: Detect container accessing host-sensitive proc paths
condition: >
open_read and container and
(fd.name startswith /proc/sysrq-trigger or
fd.name startswith /proc/kcore or
fd.name startswith /proc/kmsg or
fd.name startswith /proc/kallsyms or
fd.name startswith /sys/kernel)
output: >
Sensitive proc/sys access from container
(user=%user.name container=%container.name path=%fd.name
command=%proc.cmdline %container.info)
priority: CRITICAL
tags: [container, escape, proc_access]
# Detect cgroup escape technique
- rule: Container Cgroup Escape Attempt
desc: Detect writing to cgroup release_agent (escape technique)
condition: >
open_write and container and
(fd.name contains release_agent or
fd.name contains notify_on_release)
output: >
Cgroup escape attempt detected
(user=%user.name container=%container.name path=%fd.name
command=%proc.cmdline %container.info)
priority: CRITICAL
tags: [container, escape, cgroup]
# Detect kernel module loading from container
- rule: Container Loading Kernel Module
desc: Detect container attempting to load kernel modules
condition: >
spawned_process and container and
(proc.name in (modprobe, insmod, rmmod) or
(evt.type = init_module or evt.type = finit_module))
output: >
Kernel module load attempt from container
(user=%user.name container=%container.name command=%proc.cmdline
%container.info)
priority: CRITICAL
tags: [container, escape, kernel_module]
# Detect namespace manipulation
- rule: Container Namespace Manipulation
desc: Detect setns/unshare syscalls from container
condition: >
container and (evt.type = setns or evt.type = unshare) and
not proc.name in (containerd-shim, runc)
output: >
Namespace manipulation from container
(user=%user.name container=%container.name syscall=%evt.type
command=%proc.cmdline %container.info)
priority: CRITICAL
tags: [container, escape, namespace]
# Detect mount operations from container
- rule: Container Mount Sensitive Filesystem
desc: Detect container mounting host filesystems
condition: >
spawned_process and container and proc.name = mount and
(proc.args contains "/dev/" or proc.args contains "proc" or
proc.args contains "sysfs")
output: >
Sensitive mount operation from container
(user=%user.name container=%container.name command=%proc.cmdline
%container.info)
priority: HIGH
tags: [container, escape, mount]
Step 3: Configure Seccomp Profile for Escape Prevention
{
"defaultAction": "SCMP_ACT_ERRNO",
"archMap": [
{ "architecture": "SCMP_ARCH_X86_64", "subArchitectures": ["SCMP_ARCH_X86", "SCMP_ARCH_X32"] }
],
"syscalls": [
{
"names": [
"read", "write", "open", "close", "stat", "fstat", "lstat",
"poll", "lseek", "mmap", "mprotect", "munmap", "brk",
"rt_sigaction", "rt_sigprocmask", "ioctl", "access",
"pipe", "select", "sched_yield", "dup", "dup2",
"nanosleep", "getpid", "socket", "connect", "accept",
"sendto", "recvfrom", "bind", "listen", "getsockname",
"getpeername", "socketpair", "setsockopt", "getsockopt",
"clone", "fork", "vfork", "execve", "exit", "wait4",
"kill", "getuid", "getgid", "geteuid", "getegid",
"epoll_create", "epoll_wait", "epoll_ctl", "epoll_create1",
"futex", "set_tid_address", "set_robust_list",
"openat", "newfstatat", "readlinkat", "fchownat",
"clock_gettime", "clock_getres", "clock_nanosleep",
"getrandom", "memfd_create", "statx", "rseq"
],
"action": "SCMP_ACT_ALLOW"
},
{
"names": ["unshare", "setns", "mount", "umount2", "pivot_root",
"init_module", "finit_module", "delete_module",
"kexec_load", "kexec_file_load", "ptrace",
"reboot", "swapon", "swapoff", "sethostname",
"setdomainname", "keyctl", "bpf"],
"action": "SCMP_ACT_LOG",
"comment": "Log escape-relevant syscalls for detection"
}
]
}
Step 4: Audit Rules for Container Escape
# /etc/audit/rules.d/container-escape.rules
# Monitor namespace operations
-a always,exit -F arch=b64 -S setns -S unshare -k container_escape
-a always,exit -F arch=b64 -S mount -S umount2 -k container_mount
-a always,exit -F arch=b64 -S init_module -S finit_module -S delete_module -k kernel_module
-a always,exit -F arch=b64 -S ptrace -k process_trace
# Monitor sensitive paths
-w /var/run/docker.sock -p rwxa -k docker_socket
-w /proc/sysrq-trigger -p w -k sysrq
-w /proc/kcore -p r -k kcore_read
# Monitor container runtime
-w /usr/bin/runc -p x -k container_runtime
-w /usr/bin/containerd -p x -k container_runtime
-w /usr/bin/docker -p x -k container_runtime
Step 5: Real-Time Alert Pipeline
# Falcosidekick configuration for alert routing
config:
slack:
webhookurl: "https://hooks.slack.com/services/xxx"
minimumpriority: "critical"
messageformat: |
*Container Escape Alert*
Rule: {{ .Rule }}
Priority: {{ .Priority }}
Output: {{ .Output }}
elasticsearch:
hostport: "https://elasticsearch:9200"
index: "falco-alerts"
minimumpriority: "warning"
pagerduty:
routingkey: "xxxx"
minimumpriority: "critical"
Validation Commands
# Test Falco rules with event generator
kubectl run falco-event-generator \
--image=falcosecurity/event-generator \
--restart=Never \
-- run syscall --action PtraceAttachContainer
# Check Falco alerts
kubectl logs -n falco-system -l app.kubernetes.io/name=falco --tail=50
# Verify seccomp profile is loaded
docker inspect --format '{{.HostConfig.SecurityOpt}}' <container-id>
# Check audit logs for escape-related events
ausearch -k container_escape --interpret
References
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