Use the cluster auditing feature

Configure parameters for cluster auditing

apiVersion: audit.k8s.io/v1beta1 # This is required.
kind: Policy
# Don't generate audit events for all requests in RequestReceived stage.
omitStages:
  - "RequestReceived"
rules:
  # The following requests were manually identified as high-volume and low-risk,
  # so drop them.
  - level: None
    users: ["system:kube-proxy"]
    verbs: ["watch"]
    resources:
      - group: "" # core
        resources: ["endpoints", "services"]
  - level: None
    users: ["system:unsecured"]
    namespaces: ["kube-system"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["configmaps"]
  - level: None
    users: ["kubelet"] # legacy kubelet identity
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["nodes"]
  - level: None
    userGroups: ["system:nodes"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["nodes"]
  - level: None
    users:
      - system:kube-controller-manager
      - system:kube-scheduler
      - system:serviceaccount:kube-system:endpoint-controller
    verbs: ["get", "update"]
    namespaces: ["kube-system"]
    resources:
      - group: "" # core
        resources: ["endpoints"]
  - level: None
    users: ["system:apiserver"]
    verbs: ["get"]
    resources:
      - group: "" # core
        resources: ["namespaces"]
  # Don't log these read-only URLs.
  - level: None
    nonResourceURLs:
      - /healthz*
      - /version
      - /swagger*
  # Don't log events requests.
  - level: None
    resources:
      - group: "" # core
        resources: ["events"]
  # Secrets, ConfigMaps, and TokenReviews can contain sensitive & binary data,
  # so only log at the Metadata level.
  - level: Metadata
    resources:
      - group: "" # core
        resources: ["secrets", "configmaps"]
      - group: authentication.k8s.io
        resources: ["tokenreviews"]
  # Get repsonses can be large; skip them.
  - level: Request
    verbs: ["get", "list", "watch"]
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
  # Default level for known APIs
  - level: RequestResponse
    resources:
      - group: "" # core
      - group: "admissionregistration.k8s.io"
      - group: "apps"
      - group: "authentication.k8s.io"
      - group: "authorization.k8s.io"
      - group: "autoscaling"
      - group: "batch"
      - group: "certificates.k8s.io"
      - group: "extensions"
      - group: "networking.k8s.io"
      - group: "policy"
      - group: "rbac.authorization.k8s.io"
      - group: "settings.k8s.io"
      - group: "storage.k8s.io"
  # Default level for all other requests.
  - level: Metadata

View audit log reports

Container Service for Kubernetes (ACK) displays audit log reports on three tabs. The three tabs display the following information:

• Important operations performed by users and system components on a specific cluster.
• Source IP addresses of these operations and the regional distribution of the IP addresses.
• Details of operations on different types of resources.
• Details of operations by RAM users.
• Details of important operations, such as logging on to containers, accessing secrets, and deleting resources.

Overview of audit log reports

The Cluster Auditing page displays audit log reports on three tabs: Overview, Operations Overview, and Operation Details.

• Overview

  This tab displays an overview of the events in the cluster and the details of important events, such as connections from the Internet, command execution, resource deletion, and access to secrets.

  
  Note By default, this tab displays statistics by week. You can specify a time range and view the statistics collected during the period. You can also filter the audit information by namespace, RAM user, and status code. One or more filter conditions can be specified at a time.
• Operations Overview

  This tab displays statistics about operations on computing resources, network resources, and storage resources in the cluster. The operations include resource creation, update, deletion, and access.

  • Computing resources include deployments, StatefulSets, CronJobs, DaemonSets, jobs, and pods.
  • Network resources include services and ingresses.
  • Storage resources include ConfigMaps, secrets, and persistent volume claims (PVCs).
  
  Note

  • By default, this tab displays statistics by week. You can specify a time range and view the statistics collected during the period. You can also filter the audit information by namespace and RAM user. One or more filter conditions can be specified at a time.
  • To view details of the operations on a resource, go to the Operation Details tab.
• Operation Details

  This tab displays operation details by resource type. You can specify a resource type to query operation details in real time. This tab displays the total number of operations on resources, distribution of namespaces, operation success rates, the temporal order of operations, and other operation details.

  
  Note

  • To query operations on a CustomResourceDefinition (CRD) resource registered in Kubernetes or resources that are not displayed on this tab, enter the plural form of the specific resource name. For example, to query operations on a CRD resource named AliyunLogConfig, enter AliyunLogConfigs.
  • By default, this tab displays statistics by week. You can specify a time range and view the statistics collected during the period. You can also filter the audit information by namespace, RAM user, and status code. One or more filter conditions can be specified at a time.

View log details

1. Log on to the Log Service console.
2. Find the specific project, and click the project name.
3. Find Logstore audit-${clustered}, click , and then select Search & Analysis to view the audit logs.
   Note

   • When you create a cluster, a Logstore named audit-${clustereid} is automatically created in the specific project.
   • By default, indexes are set up in the Logstore. We recommend that you do not modify the indexes. Otherwise, reports may fail to be generated.

You can query audit logs by using the following methods:

• To query the operations performed by a RAM user, enter the user name, and click Search & Analyze.
• To query the operations performed on a resource, enter the resource name, and click Search & Analyze.
• To filter out the operations performed by system components, enter NOT user.username: node NOT user.username: serviceaccount NOT user.username: apiserver NOT user.username: kube-scheduler NOT user.username: kube-controller-manager, and click Search & Analyze.

For more information about how to query logs, see Query methods.

Configure an alert rule

Log Service allows you to configure an alert rule for operations on some resources in real time. Available notification methods includeDingTalk chatbot webhooks,custom webhooks, and Alibaba Cloud Message Center. For more information, see Configure an alert rule for Log Service.

Example 1: Alerts on command execution on containers

To monitor command execution on containers, alerts must be sent at the earliest opportunity when a user attempts to log on to a container or run commands on a container. The alert notification must include the following information: the container that was logged on, executed commands, the operator, the event ID, the operation time, and the source IP address.

• Sample query statement:

  verb : create and objectRef.subresource:exec and stage:  ResponseStarted | SELECT auditID as "Event ID", date_format(from_unixtime(__time__), '%Y-%m-%d %T' ) as "Operation time",  regexp_extract("requestURI", '([^\?] *)/exec\?.*', 1)as "Resource",  regexp_extract("requestURI", '\?(.*)', 1)as "Command" ,"responseStatus.code" as "Status code",
   CASE 
   WHEN "user.username" ! = 'kubernetes-admin' then "user.username"
   WHEN "user.username" = 'kubernetes-admin' and regexp_like("annotations.authorization.k8s.io/reason", 'RoleBinding') then regexp_extract("annotations.authorization.k8s.io/reason", ' to User "(\w+)"', 1)
   ELSE 'kubernetes-admin' END  
   as "Account name", 
  CASE WHEN json_array_length(sourceIPs) = 1 then json_format(json_array_get(sourceIPs, 0)) ELSE  sourceIPs END
  as "Source IP address" limit 100

• The conditional expression is Event =~ ". *".

Example 2: Alerts on failed Internet access to the API server

To prevent attacks on a cluster that allows Internet access, you must monitor the number of connections from the Internet and the connection failure rate. Alerts are sent at the earliest opportunity when the number of connections and the connection failure rate both exceed the specified thresholds. The alert notification must include the following information: the source IP address, the region to which the source IP address belongs, and whether the source IP address is high-risk. In the following query statement, alerts are generated if the number of connections from the Internet exceeds 10 and the connection failure rate exceeds 50%.

• Sample query statement:

  * | select ip as "Source IP address", total as "Number of connections", round(rate * 100, 2) as "Connection failure rate", failCount as "Number of invalid connections", CASE when security_check_ip(ip) = 1 then 'yes' else 'no' end  as "Whether the IP address is high-risk",  ip_to_country(ip) as "Country", ip_to_province(ip) as "Province", ip_to_city(ip) as "City", ip_to_provider(ip) as "ISP" from (select CASE WHEN json_array_length(sourceIPs) = 1 then json_format(json_array_get(sourceIPs, 0)) ELSE  sourceIPs END
  as ip, count(1) as total,
  sum(CASE WHEN "responseStatus.code" < 400 then 0 
  ELSE 1 END) * 1.0 / count(1) as rate,
  count_if("responseStatus.code" = 403) as failCount
  from log  group by ip limit 10000) where ip_to_domain(ip) ! = 'intranet'  having "Number of connections" > 10 and "Connection failure rate" > 50 ORDER by "Number of connections" desc limit 100

• The conditional expression is Source IP address =~ ". *".

Enable cluster auditing

By default, the Enable Log Service check box is selected when you create a cluster. In this case, cluster auditing is automatically enabled. If cluster auditing is disabled, take the following steps to enable this feature. You cannot manually enable cluster auditing for a managed cluster.

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, click the name of a cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page of the cluster, choose Security > Cluster Auditing. If cluster auditing is disabled, you are prompted to enable this feature.
5. Click Enable Cluster Auditing Now. Select an existing project or create a project, and then click OK.
   If the following page appears, cluster auditing is enabled.

Disable cluster auditing

You can take the following steps to disable cluster auditing:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, click the name of a cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page of the cluster, choose Security > Cluster Auditing.
5. In the upper-right corner, click Disable Cluster Auditing.

Billing method

• On the Bill Details page, you can view the billing information about audit logs. For more information, see Billing management.
• For more information about the billing method of cluster auditing, see Pay-as-you-go.

Support for third-party logging services

You can find the source log file in the /var/log/kubernetes/kubernetes.audit path of a master node. This file is in standard JSON format. When you create a cluster, you can specify a third-party logging service to collect and search audit logs.