Service Access Strategy - ABAC

Attribute-based Access Control (ABAC) is an authorization model that evaluates principal/user attributes rather than roles to determine access. With ABAC, the access policies enforce access decisions based on the attributes of the authenticated subject/principal, resource, action, and environment involved in an access request. The principal is the user requesting access to a resource to perform an action. Principal attributes in a user profile include ID, job roles, group memberships, departmental and organizational memberships, management level, security clearance, and other identifying criteria.

:information_source: Usage

Note that comparison of principal/required attribute names is case-sensitive. Exact matches are required for any individual attribute name. Furthermore, note that if the CAS server is configured to cache attributes upon release, all required attributes must also be released to the relying party. See this guide for more info on attribute release and filters.

The ABAC strategy allows one to configure a service with the following properties:

Field Description
requiredAttributes A Map of required principal attribute names along with the set of values for each attribute. These attributes MUST be available to the authenticated Principal and resolved before CAS can proceed, providing an option for role-based access control from the CAS perspective. If no required attributes are presented, the check will be entirely ignored.
requireAllAttributes Flag to toggle to control the behavior of required attributes. Default is true, which means all required attribute names must be present. Otherwise, at least one matching attribute name may suffice. Note that this flag only controls which and how many of the attribute names must be present. If attribute names satisfy the CAS configuration, at the next step at least one matching attribute value is required for the access strategy to proceed successfully.
caseInsensitive Indicates whether matching on required attribute values should be done in a case-insensitive manner. Default is false
rejectedAttributes A Map of rejected principal attribute names along with the set of values for each attribute. These attributes MUST NOT be available to the authenticated Principal so that access may be granted. If none is defined, the check is entirely ignored.

You can also tune the ABAC strategy to conditionally activate and enforce the policy. See this guide for more info.

  • Control access using a Map of required principal attribute names along with the set of values for each attribute.

    :information_source: Supported Syntax

    Required values for a given attribute support regular expression patterns. For example, a phone attribute could require a value pattern of \d\d\d-\d\d\d-\d\d\d\d.

    To access the service, the principal must have a cn attribute with the value of admin AND a givenName attribute with the value of Administrator:

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "ssoEnabled" : true,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ "admin" ] ],
      "givenName" : [ "java.util.HashSet", [ "Administrator" ] ]
    }
  }
}

  • To access the service, the principal must have a cn attribute with the value of admin OR a givenName attribute with the value of Administrator:

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "ssoEnabled" : true,
    "requireAllAttributes": false,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ "admin" ] ],
      "givenName" : [ "java.util.HashSet", [ "Administrator" ] ]
    }
  }
}

    To access the service, the principal must have a cn attribute whose value is either admin, Admin or TheAdmin.

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "ssoEnabled" : true,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ "admin", "Admin", "TheAdmin" ] ]
    }
  }
}

  • To access the service, the principal must have a cn attribute whose value is either admin, Admin or TheAdmin, OR the principal must have a member attribute whose value is either admins, adminGroup or staff.

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "requireAllAttributes" : false,
    "ssoEnabled" : true,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ "admin", "Admin", "TheAdmin" ] ],
      "member" : [ "java.util.HashSet", [ "admins", "adminGroup", "staff" ] ]
    }
  }
}

  • To access the service, the principal must have a cn attribute whose values must contain admin and the overall set of resolved principal attributes must already have found an attribute for name.

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "requireAllAttributes" : false,
    "ssoEnabled" : true,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ 
        "groovy { return attributes.containsKey('name') && currentValues.contains('admin') }" 
      ]]
    }
  }
}

    To prepare CAS to support and integrate with Apache Groovy, please review this guide.

  • To access the service, the principal must have a cn attribute whose value is either admin, Admin or TheAdmin, OR the principal must have a member attribute whose value is either admins, adminGroup or staff. The principal also must not have an attribute role whose value matches the pattern deny.+.

    

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    {
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "testId",
  "name" : "testId",
  "id" : 1,
  "accessStrategy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServiceAccessStrategy",
    "enabled" : true,
    "requireAllAttributes" : false,
    "ssoEnabled" : true,
    "requiredAttributes" : {
      "@class" : "java.util.HashMap",
      "cn" : [ "java.util.HashSet", [ "admin", "Admin", "TheAdmin" ] ],
      "member" : [ "java.util.HashSet", [ "admins", "adminGroup", "staff" ] ]
    },
    "rejectedAttributes" : {
      "@class" : "java.util.HashMap",
      "role" : [ "java.util.HashSet", [ "deny.+" ] ]
    }
  }
}
    :information_source: Supported Syntax

    Rejected values for a given attribute support regular expression patterns. For example, a role attribute could be designed with a value value pattern of admin-.*.