Kubernetes Secret or ConfigMap Access via Azure Arc Proxy

  1[metadata]
  2creation_date = "2026/03/10"
  3integration = ["kubernetes"]
  4maturity = "production"
  5updated_date = "2026/03/10"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Detects when secrets or configmaps are accessed, created, modified, or deleted in a Kubernetes cluster by the Azure Arc
 11AAD proxy service account. When operations are routed through the Azure Arc Cluster Connect proxy, the Kubernetes audit
 12log records the acting user as `system:serviceaccount:azure-arc:azure-arc-kube-aad-proxy-sa` with the actual caller
 13identity in the `impersonatedUser` field. This pattern indicates that someone is accessing the cluster through the Azure
 14ARM API rather than directly via kubectl against the API server. While legitimate for Arc-managed workflows, adversaries
 15with stolen service principal credentials can abuse Arc Cluster Connect to read, exfiltrate, or modify secrets and
 16configmaps while appearing as the Arc proxy service account in K8s audit logs.
 17"""
 18false_positives = [
 19    """
 20    Azure Arc system components may create or update secrets and configmaps in the azure-arc and azure-arc-release
 21    namespaces during normal cluster management. Filter by namespace to exclude these.
 22    """,
 23    """
 24    Helm operations managed through Arc may create release secrets (prefixed with sh.helm.release.v1). These are normal
 25    Arc lifecycle operations.
 26    """,
 27]
 28from = "now-5d"
 29interval = "9m"
 30language = "esql"
 31license = "Elastic License v2"
 32name = "Kubernetes Secret or ConfigMap Access via Azure Arc Proxy"
 33note = """## Triage and analysis
 34
 35### Investigating Kubernetes Secret or ConfigMap Access via Azure Arc Proxy
 36
 37When Kubernetes operations are performed through Azure Arc Cluster Connect, the K8s audit log shows the Arc AAD proxy
 38service account as the authenticated user, with the actual Azure AD identity in the `impersonatedUser` field. This
 39rule detects non-system secret and configmap access — including reads, writes, and deletions — routed through this
 40proxy path. Read operations (`get`, `list`) are particularly important to detect as they represent the most common
 41adversary action: exfiltrating secrets without leaving obvious modification traces.
 42
 43### Possible investigation steps
 44
 45- Check the `kubernetes.audit.impersonatedUser.username` field — this contains the Azure AD object ID of the actual
 46  caller. Cross-reference with Azure AD to identify the service principal or user.
 47- Review the `kubernetes.audit.impersonatedUser.extra.oid` field for the Azure AD object ID.
 48- Examine the namespace — operations in `default` or application namespaces are more suspicious than `azure-arc` or
 49  `kube-system`.
 50- Check the `kubernetes.audit.objectRef.name` — look for suspicious secret/configmap names that don't match known
 51  application resources.
 52- Correlate with Azure Activity Logs for the same time window to find the `LISTCLUSTERUSERCREDENTIAL` operation that
 53  initiated the Arc proxy session.
 54- Review Azure Sign-In Logs for the impersonated identity's authentication source IP and geolocation.
 55
 56### Response and remediation
 57
 58- If the impersonated identity is not recognized, revoke its Azure AD credentials immediately.
 59- Remove the ClusterRoleBinding or RoleBinding that grants the identity access to secrets/configmaps.
 60- Rotate any Kubernetes secrets that may have been read or exfiltrated.
 61- Review the Arc connection and consider disconnecting it if compromised.
 62"""
 63references = [
 64    "https://learn.microsoft.com/en-us/azure/azure-arc/kubernetes/cluster-connect",
 65    "https://microsoft.github.io/Threat-Matrix-for-Kubernetes/",
 66    "https://www.ibm.com/think/x-force/identifying-abusing-azure-arc-for-hybrid-escalation-persistence",
 67    "https://cloud.google.com/blog/topics/threat-intelligence/escalating-privileges-azure-kubernetes-services",
 68    "https://www.wiz.io/blog/lateral-movement-risks-in-the-cloud-and-how-to-prevent-them-part-3-from-compromis",
 69]
 70risk_score = 47
 71rule_id = "220d92c6-479d-4a49-9cc0-3a29756dad0c"
 72severity = "medium"
 73tags = [
 74    "Data Source: Kubernetes",
 75    "Domain: Kubernetes",
 76    "Domain: Cloud",
 77    "Use Case: Threat Detection",
 78    "Tactic: Credential Access",
 79    "Tactic: Collection",
 80    "Resources: Investigation Guide",
 81]
 82timestamp_override = "event.ingested"
 83type = "esql"
 84
 85query = '''
 86FROM logs-kubernetes.audit_logs-* metadata _id, _version, _index
 87| WHERE STARTS_WITH(kubernetes.audit.user.username, "system:serviceaccount:azure-arc:")
 88    AND kubernetes.audit.objectRef.resource IN ("secrets", "configmaps")
 89    AND kubernetes.audit.verb IN ("get", "list", "create", "update", "patch", "delete")
 90    AND kubernetes.audit.objectRef.namespace NOT IN ("azure-arc", "azure-arc-release", "kube-system")
 91    AND NOT STARTS_WITH(kubernetes.audit.objectRef.name, "sh.helm.release.v1")
 92
 93| STATS
 94    Esql.verb_values = VALUES(kubernetes.audit.verb),
 95    Esql.resource_type_values = VALUES(kubernetes.audit.objectRef.resource),
 96    Esql.resource_name_values = VALUES(kubernetes.audit.objectRef.name),
 97    Esql.namespace_values = VALUES(kubernetes.audit.objectRef.namespace),
 98    Esql.acting_user_values = VALUES(kubernetes.audit.user.username),
 99    Esql.user_agent_values = VALUES(kubernetes.audit.userAgent),
100    Esql.source_ips_values = VALUES(kubernetes.audit.sourceIPs),
101    Esql.response_code_values = VALUES(kubernetes.audit.responseStatus.code),
102    Esql.timestamp_first_seen = MIN(@timestamp),
103    Esql.timestamp_last_seen = MAX(@timestamp),
104    Esql.event_count = COUNT(*)
105    BY kubernetes.audit.impersonatedUser.username
106
107| WHERE Esql.timestamp_first_seen >= NOW() - 9 minutes
108| KEEP *
109'''
110
111
112[[rule.threat]]
113framework = "MITRE ATT&CK"
114[[rule.threat.technique]]
115id = "T1552"
116name = "Unsecured Credentials"
117reference = "https://attack.mitre.org/techniques/T1552/"
118[[rule.threat.technique.subtechnique]]
119id = "T1552.007"
120name = "Container API"
121reference = "https://attack.mitre.org/techniques/T1552/007/"
122
123
124
125[rule.threat.tactic]
126id = "TA0006"
127name = "Credential Access"
128reference = "https://attack.mitre.org/tactics/TA0006/"
129[[rule.threat]]
130framework = "MITRE ATT&CK"
131[[rule.threat.technique]]
132id = "T1530"
133name = "Data from Cloud Storage"
134reference = "https://attack.mitre.org/techniques/T1530/"
135
136
137[rule.threat.tactic]
138id = "TA0009"
139name = "Collection"
140reference = "https://attack.mitre.org/tactics/TA0009/"