Deny Secret Service Account Token Type in CEL expressions

 1apiVersion: kyverno.io/v1
 2kind: ClusterPolicy
 3metadata:
 4  name: deny-secret-service-account-token-type
 5  annotations:
 6    policies.kyverno.io/title: Deny Secret Service Account Token Type in CEL expressions
 7    policies.kyverno.io/category: Security in CEL 
 8    kyverno.io/kubernetes-version: "1.26-1.27"
 9    kyverno.io/kyverno-version: 1.11.0
10    policies.kyverno.io/severity: medium
11    policies.kyverno.io/subject: Secret, ServiceAccount
12    policies.kyverno.io/description: >-
13      Before version 1.24, Kubernetes automatically generated Secret-based tokens 
14      for ServiceAccounts. When creating a Secret, you can specify its type using the 
15      type field of the Secret resource . The type kubernetes.io/service-account-token
16      is used for legacy ServiceAccount tokens . These legacy Tokens can
17      be of security concern and should be audited.
18spec:
19  validationFailureAction: Audit
20  background: true
21  rules:
22  - name: deny-secret-service-account-token-type
23    match:
24      any:
25      - resources:
26          kinds:
27          - Secret
28          operations:
29          - CREATE
30          - UPDATE
31    validate:
32      cel:
33        expressions:
34          - expression: "object.type != 'kubernetes.io/service-account-token'"
35            message: "Secret ServiceAccount token type is not allowed."
36