Kubernetes Pod Attached To Host Network

Severity: medium
Group by: namespace, username
Log types: Amazon.EKS.Audit, Azure.MonitorActivity, GCP.AuditLog
Tags: Kubernetes, Security Control, Escape to Host, Unified Detection
Reference: - https://kubernetes.io/docs/concepts/security/pod-security-standards/#host-namespaces - https://securitylabs.datadoghq.com/articles/kubernetes-security-fundamentals-part-6/
Source: github.com/panther-labs/panther-analysis

This detection monitors for the creation of pods which are attached to the host's network. This allows a pod to listen to all network traffic for all deployed compute on that particular node and communicate with other compute on the network namespace. Attackers can use this to capture secrets passed in arguments or connections.

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1611` Escape to Host

Rule body yaml

AnalysisType: rule
RuleID: "Kubernetes.Pod.Host.Network"
DisplayName: "Kubernetes Pod Attached To Host Network"
Enabled: true
Filename: k8s_pod_host_network.py
LogTypes:
  - Amazon.EKS.Audit
  - Azure.MonitorActivity
  - GCP.AuditLog
Tags:
  - Kubernetes
  - Security Control
  - Escape to Host
  - Unified Detection
Severity: Medium
Description:
  This detection monitors for the creation of pods which are attached to the host's network.
  This allows a pod to listen to all network traffic for all deployed compute on that particular
  node and communicate with other compute on the network namespace. Attackers can use this to
  capture secrets passed in arguments or connections.
Reports:
  MITRE ATT&CK:
    - TA0004:T1611 # Escape to Host
Runbook: |
  1. Find all pod creation events by the username in the 24 hours before the alert to establish normal deployment behavior
  2. Check if the pod namespace indicates system infrastructure purpose (kube-system, kube-public) which may be legitimate
  3. Review all pods with hostNetwork by this user in the past 30 days to identify if this is an established pattern or anomalous activity
Reference: >
  - https://kubernetes.io/docs/concepts/security/pod-security-standards/#host-namespaces
  - https://securitylabs.datadoghq.com/articles/kubernetes-security-fundamentals-part-6/
Tests:
  - Name: EKS Pod With Host Network
    ExpectedResult: true
    Log:
      {
        "kind": "Event",
        "apiVersion": "audit.k8s.io/v1",
        "auditID": "abc-123",
        "verb": "create",
        "user": {"username": "admin@example.com"},
        "sourceIPs": ["1.2.3.4"],
        "userAgent": "kubectl/v1.28.0",
        "objectRef": {
          "resource": "pods",
          "namespace": "default",
          "name": "nginx-test",
          "apiVersion": "v1"
        },
        "responseStatus": {"code": 201},
        "requestObject": {
          "kind": "Pod",
          "apiVersion": "v1",
          "metadata": {"name": "nginx-test", "namespace": "default"},
          "spec": {
            "hostNetwork": true,
            "containers": [{"name": "nginx", "image": "nginx"}]
          }
        },
        "p_log_type": "Amazon.EKS.Audit",
        "p_source_label": "eks-cluster"
      }
  - Name: AKS Pod With Host Network
    ExpectedResult: true
    Log:
      {
        "p_log_type": "Azure.MonitorActivity",
        "category": "kube-audit",
        "operationName": "Microsoft.ContainerService/managedClusters/diagnosticLogs/Read",
        "properties": {
          "log": "{\"kind\":\"Event\",\"apiVersion\":\"audit.k8s.io/v1\",\"auditID\":\"abc-123\",\"verb\":\"create\",\"user\":{\"username\":\"admin@example.com\"},\"sourceIPs\":[\"10.0.0.1\"],\"objectRef\":{\"resource\":\"pods\",\"namespace\":\"default\",\"name\":\"nginx-test\"},\"responseStatus\":{\"code\":201},\"requestObject\":{\"kind\":\"Pod\",\"spec\":{\"hostNetwork\":true,\"containers\":[{\"name\":\"nginx\",\"image\":\"nginx\"}]}}}"
        },
        "p_source_label": "aks-cluster"
      }
  - Name: GCP GKE Pod With Host Network
    ExpectedResult: true
    Log:
      {
        "protoPayload": {
          "authenticationInfo": {"principalEmail": "user@example.com"},
          "authorizationInfo": [{
            "granted": true,
            "permission": "io.k8s.core.v1.pods.create",
            "resource": "core/v1/namespaces/default/pods/nginx-test"
          }],
          "methodName": "io.k8s.core.v1.pods.create",
          "request": {
            "@type": "core.k8s.io/v1.Pod",
            "spec": {
              "hostNetwork": true,
              "containers": [{"name": "nginx", "image": "nginx"}]
            }
          },
          "requestMetadata": {"callerIP": "1.2.3.4"},
          "resourceName": "core/v1/namespaces/default/pods/nginx-test",
          "serviceName": "k8s.io"
        },
        "resource": {
          "type": "k8s_cluster",
          "labels": {"project_id": "test-project"}
        },
        "p_log_type": "GCP.AuditLog",
        "p_source_label": "gke-cluster"
      }
  - Name: Pod Without Host Network
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "create",
        "objectRef": {"resource": "pods", "namespace": "default"},
        "responseStatus": {"code": 201},
        "requestObject": {
          "kind": "Pod",
          "spec": {
            "hostNetwork": false,
            "containers": [{"name": "nginx", "image": "nginx"}]
          }
        },
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Pod Creation Failed
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "create",
        "objectRef": {"resource": "pods", "namespace": "default"},
        "responseStatus": {"code": 403, "status": "Failure"},
        "requestObject": {
          "kind": "Pod",
          "spec": {
            "hostNetwork": true,
            "containers": [{"name": "nginx"}]
          }
        },
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Not a Pod Creation
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "get",
        "objectRef": {"resource": "pods", "namespace": "default"},
        "p_log_type": "Amazon.EKS.Audit"
      }

Detection logic

Condition

not (verb ne "create" or resource ne "pods")
not (responseStatus is_not_null and (responseStatus.code ge "400" or (responseStatus.code ge "1" and responseStatus.code le "16")))
not (username is_not_null and (username in ["masterclient", "aksService"] or (username starts_with "system:" and username not contains "serviceaccount")) and namespace is_not_null and namespace in ["kube-system", "gke-system", "kube-node-lease", "kube-public"])
hostNetwork eq "True"

This rule also runs imperative logic the parser cannot express as a filter; the conditions above are the structured part it could extract.

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`username`	contains	`serviceaccount`
`username`	starts_with	`system:`
`username`	in	`aksService`, `masterclient`
`namespace`	in	`gke-system`, `kube-node-lease`, `kube-public`, `kube-system`
`namespace`	is_not_null	(no value, null check)
`username`	is_not_null	(no value, null check)
`responseStatus.code`	ge	`1`
`responseStatus.code`	le	`16`
`responseStatus.code`	ge	`400`
`responseStatus`	is_not_null	(no value, null check)
`resource`	ne	`pods`
`verb`	ne	`create`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`hostNetwork`	eq	`True`
`username`	contains	`serviceaccount`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`username`
`sourceIPs`
`userAgent`
`namespace`
`verb`
`resource`
`requestURI`
`responseStatus`
`cluster`	`p_source_label`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)