Kubernetes System Role Modified or Deleted

Status: Experimental
Severity: critical
Group by: name, username
Log types: Amazon.EKS.Audit, Azure.MonitorActivity, GCP.AuditLog
Tags: Kubernetes, Privilege Escalation, Defense Evasion, Persistence, RBAC, Unified Detection
Reference: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#default-roles-and-role-bindings
Source: github.com/panther-labs/panther-analysis

This detection monitors for modifications or deletions of system ClusterRoles/Roles (those starting with "system:"). These are built-in Kubernetes roles for control plane components like kube-scheduler, kube-controller-manager, and system:admin. Tampering with system roles can break cluster functionality, create privilege escalation backdoors, or disable security controls. Legitimate modifications to system roles are extremely rare outside of cluster upgrades.

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1078.004` Valid Accounts: Cloud Accounts, `T1098` Account Manipulation
Privilege Escalation	`T1078.004` Valid Accounts: Cloud Accounts, `T1098` Account Manipulation
Stealth	`T1078.004` Valid Accounts: Cloud Accounts
Defense Impairment	`T1222` File and Directory Permissions Modification

Rule body yaml

AnalysisType: rule
RuleID: "Kubernetes.SystemRole.Modified"
DisplayName: "Kubernetes System Role Modified or Deleted"
Enabled: true
Status: Experimental
Filename: k8s_system_role_modified.py
LogTypes:
  - Amazon.EKS.Audit
  - Azure.MonitorActivity
  - GCP.AuditLog
Tags:
  - Kubernetes
  - Privilege Escalation
  - Defense Evasion
  - Persistence
  - RBAC
  - Unified Detection
Severity: Critical
Description: >
  This detection monitors for modifications or deletions of system ClusterRoles/Roles (those starting with "system:").
  These are built-in Kubernetes roles for control plane components like kube-scheduler, kube-controller-manager, and
  system:admin. Tampering with system roles can break cluster functionality, create privilege escalation backdoors,
  or disable security controls. Legitimate modifications to system roles are extremely rare outside of cluster upgrades.
Runbook: |
  1. Immediately review the changes made to the system role and determine if this represents a cluster upgrade or unauthorized tampering
  2. If unauthorized, revert the role to its original state using kubectl or restore from backup, then revoke credentials for the modifying user
  3. Search for all RBAC modifications by this user across all clusters in the past 7 days and audit all API operations to identify other malicious changes
Reports:
  MITRE ATT&CK:
    - TA0004:T1078.004 # Privilege Escalation: Valid Accounts - Cloud Accounts
    - TA0005:T1222 # Defense Evasion: File and Directory Permissions Modification
    - TA0003:T1098 # Persistence: Account Manipulation
Reference: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#default-roles-and-role-bindings
DedupPeriodMinutes: 60
SummaryAttributes:
  - username
  - resource
  - name
  - p_source_label
Tests:
  - Name: EKS system ClusterRole modified
    ExpectedResult: true
    Log:
      {
        "kind": "Event",
        "apiVersion": "audit.k8s.io/v1",
        "verb": "update",
        "user": {"username": "attacker@example.com"},
        "sourceIPs": ["203.0.113.42"],
        "userAgent": "kubectl/v1.28.0",
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:node",
          "apiGroup": "rbac.authorization.k8s.io",
          "apiVersion": "v1"
        },
        "responseStatus": {"code": 200},
        "requestObject": {
          "kind": "ClusterRole",
          "metadata": {"name": "system:node"},
          "rules": [
            {
              "apiGroups": ["*"],
              "resources": ["*"],
              "verbs": ["*"]
            }
          ]
        },
        "p_log_type": "Amazon.EKS.Audit",
        "p_source_label": "eks-cluster"
      }
  - Name: AKS system ClusterRole deleted
    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\",\"verb\":\"delete\",\"user\":{\"username\":\"malicious-user@example.com\"},\"sourceIPs\":[\"1.2.3.4\"],\"objectRef\":{\"resource\":\"clusterroles\",\"name\":\"system:kube-scheduler\",\"apiGroup\":\"rbac.authorization.k8s.io\"},\"responseStatus\":{\"code\":200}}"
        },
        "p_source_label": "aks-cluster"
      }
  - Name: GKE system Role patched
    ExpectedResult: true
    Log:
      {
        "protoPayload": {
          "authenticationInfo": {"principalEmail": "user@company.com"},
          "authorizationInfo": [{
            "granted": true,
            "permission": "io.k8s.rbac.v1.roles.patch",
            "resource": "rbac.authorization.k8s.io/v1/namespaces/kube-system/roles/system:controller"
          }],
          "methodName": "io.k8s.rbac.v1.roles.patch",
          "requestMetadata": {"callerIP": "8.8.8.8"},
          "resourceName": "rbac.authorization.k8s.io/v1/namespaces/kube-system/roles/system:controller",
          "serviceName": "k8s.io"
        },
        "resource": {
          "type": "k8s_cluster",
          "labels": {"project_id": "test-project"}
        },
        "p_log_type": "GCP.AuditLog",
        "p_source_label": "gke-cluster"
      }
  - Name: EKS system:admin ClusterRole modified
    ExpectedResult: true
    Log:
      {
        "kind": "Event",
        "verb": "patch",
        "user": {"username": "attacker@example.com"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:admin",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 200},
        "p_log_type": "Amazon.EKS.Audit",
        "p_source_label": "eks-cluster"
      }
  - Name: System:coredns modified (excluded - expected)
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "update",
        "user": {"username": "admin@example.com"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:coredns",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 200},
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Non-system role modified
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "update",
        "user": {"username": "admin@example.com"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "custom-admin",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 200},
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: System principal modifying system role (excluded)
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "update",
        "user": {"username": "system:serviceaccount:kube-system:operator"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:node",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 200},
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Failed modification (excluded)
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "update",
        "user": {"username": "attacker@example.com"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:admin",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 403},
        "p_log_type": "Amazon.EKS.Audit"
      }
  - Name: Reading system role (not modifying)
    ExpectedResult: false
    Log:
      {
        "kind": "Event",
        "verb": "get",
        "user": {"username": "admin@example.com"},
        "objectRef": {
          "resource": "clusterroles",
          "name": "system:admin",
          "apiGroup": "rbac.authorization.k8s.io"
        },
        "responseStatus": {"code": 200},
        "p_log_type": "Amazon.EKS.Audit"
      }

Detection logic

Condition

not (verb not in ["update", "patch", "delete"] or resource not in ["roles", "clusterroles"])
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")))
name starts_with "system:" or name starts_with "eks:"
name not in ["system:coredns", "system:managed-certificate-controller"]

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`
`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`	in	`clusterroles`, `roles`
`verb`	in	`delete`, `patch`, `update`
`name`	in	`system:coredns`, `system:managed-certificate-controller`

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
`name`	starts_with	`eks:` `system:`
`resource`	in	`clusterroles` `roles`
`username`	contains	`serviceaccount`
`verb`	in	`delete` `patch` `update`

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`
`name`

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`/`	Focus search
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`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)