Kubernetes Secret Get or List with Suspicious User Agent

  1[metadata]
  2creation_date = "2026/04/22"
  3integration = ["kubernetes"]
  4maturity = "production"
  5updated_date = "2026/08/18"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10Detects read access to Kubernetes Secrets (get/list) with a user agent matching a curated set of non-standard or 
 11attacker-leaning clients, for example minimal HTTP tooling, common scripting stacks, default library fingerprints, or
 12distribution-tagged strings associated with offensive-security Linux images. Legitimate in-cluster automation usually 
 13presents stable, purpose-specific user agents (for example controller or client-go variants used by known components). 
 14"""
 15false_positives = [
 16    """
 17    Operators may use ad hoc HTTP clients, scripts, or penetration-test images during approved exercises or break-glass
 18    maintenance; validate tickets, source IP, and identity before treating as compromise.
 19    """,
 20    """
 21    Internal automation built with generic libraries can resemble suspicious user agents; baseline known jobs and tune
 22    by service account, namespace, or stable source IP allowlists.
 23    """,
 24]
 25index = ["logs-kubernetes.audit_logs-*"]
 26language = "kuery"
 27license = "Elastic License v2"
 28name = "Kubernetes Secret Get or List with Suspicious User Agent"
 29note = """## Triage and analysis
 30
 31### Investigating Kubernetes Secret Get or List with Suspicious User Agent
 32
 33The rule matches Kubernetes audit events for **secret** `get`/`list` where **`user_agent.original`** matches a **small
 34allowlist of suspicious patterns** (scripting runtimes, bare HTTP clients, and known offensive-distro markers) and
 35**`source.ip` is populated**. It is meant to highlight **credential access** where the client fingerprint does not look
 36like routine kubectl or well-known controller traffic relative to your environment.
 37
 38### Possible investigation steps
 39
 40- Tie `user.name` (and `kubernetes.audit.impersonatedUser.*` if present) to a human, service account, or cloud identity
 41  and validate whether that principal should use this user-agent profile against the targeted namespaces and secret names.
 42- Review `kubernetes.audit.objectRef.namespace` and `kubernetes.audit.objectRef.name` for high-value objects (service
 43  account tokens, cloud IAM bindings, registry pulls, TLS bundles).
 44- Pivot on `source.ip` in VPC flow, VPN, or proxy logs to determine origin (employee laptop, compromised host, cloud
 45  instance) and correlate with other API bursts or exec activity.
 46- Check `kubernetes.audit.annotations.authorization_k8s_io/decision` for successful reads versus failed probing.
 47
 48### False positive analysis
 49
 50- CI, GitOps, or one-off scripts can emit generic user agents with broad RBAC; exclude stable pipelines and service
 51  accounts after review.
 52- Local API server loopback may still populate `source.ip` in some topologies; compare with expected control-plane paths.
 53
 54### Response and remediation
 55
 56- If unauthorized, rotate affected secrets and credentials, revoke tokens or kubeconfigs for the identity, tighten RBAC,
 57  and block or isolate the source host at the network edge to the API server where appropriate.
 58"""
 59references = [
 60    "https://attack.mitre.org/techniques/T1552/007/",
 61    "https://kubernetes.io/docs/concepts/configuration/secret/",
 62]
 63risk_score = 73
 64rule_id = "a4c8e901-2b7f-4d6e-9a3c-8e1f0d5b6c2a"
 65severity = "high"
 66tags = [
 67    "Data Source: Kubernetes",
 68    "Data Source: Kubernetes API Server Audit Logs",
 69    "Domain: Kubernetes",
 70    "Platform: Kubernetes",
 71    "Use Case: Threat Detection",
 72    "Tactic: Credential Access",
 73    "Resources: Investigation Guide",
 74]
 75timestamp_override = "event.ingested"
 76type = "query"
 77query = '''
 78data_stream.dataset:"kubernetes.audit_logs" and
 79event.action:(get or list) and
 80kubernetes.audit.objectRef.resource:"secrets" and
 81event.outcome:"success" and
 82user_agent.original:(curl* or python* or Python* or wget* or Go-http* or perl* or java* or node* or php* or *distrib#kali* or *kali-amd64* or *kali-arm64* or Bun* or axios* or undici*) and
 83source.ip:*
 84'''
 85
 86[[rule.threat]]
 87framework = "MITRE ATT&CK"
 88
 89[[rule.threat.technique]]
 90id = "T1552"
 91name = "Unsecured Credentials"
 92reference = "https://attack.mitre.org/techniques/T1552/"
 93
 94[[rule.threat.technique.subtechnique]]
 95id = "T1552.007"
 96name = "Container API"
 97reference = "https://attack.mitre.org/techniques/T1552/007/"
 98
 99[rule.threat.tactic]
100id = "TA0006"
101name = "Credential Access"
102reference = "https://attack.mitre.org/tactics/TA0006/"