Configuring SAML single-sign-on on the Elastic Stackedit

The Elastic Stack supports SAML single-sign-on (SSO) into Kibana, using Elasticsearch as a backend service. In SAML terminology, the Elastic Stack is operating as a Service Provider.

The other component that is needed to enable SAML single-sign-on is the Identity Provider, which is a service that handles your credentials and performs that actual authentication of users.

If you are interested in configuring SSO into Kibana, then you will need to provide Elasticsearch with information about your Identity Provider, and you will need to register the Elastic Stack as a known Service Provider within that Identity Provider. There are also a few configuration changes that are required in Kibana to activate the SAML authentication provider.

The SAML support in Kibana is designed on the expectation that it will be the primary (or sole) authentication method for users of that Kibana instance. Once you enable SAML authentication in Kibana it will affect all users who try to login. The Configuring Kibana section provides more detail about how this works.

The identity provideredit

The Elastic Stack supports the SAML 2.0 Web Browser SSO and the SAML 2.0 Single Logout profiles and can integrate with any Identity Provider (IdP) that supports at least the SAML 2.0 Web Browser SSO Profile. It has been tested with a number of popular IdP implementations, such as Microsoft Active Directory Federation Services (ADFS).

This guide assumes that you have an existing IdP and wish to add Kibana as a Service Provider.

The Elastic Stack uses a standard SAML metadata document, in XML format that defines the capabilities and features of your IdP. You should be able to download or generate such a document within your IdP administration interface.

Download the IdP metadata document and store it within the config directory on each Elasticsearch node. For the purposes of this guide, we will assume that you are storing it as config/saml/idp-metadata.xml.

The IdP will have been assigned an identifier (EntityID in SAML terminology) which is most commonly expressed in Uniform Resource Identifier (URI) form. Your admin interface may tell you what this is, or you might need to read the metadata document to find it - look for the entityID attribute on the EntityDescriptor element.

Most IdPs will provide an appropriate metadata file with all the features that the Elastic Stack requires, and should only require the configuration steps described below. For completeness sake, the minimum requirements that the Elastic Stack has for the IdP’s metadata are:

  • An <EntityDescriptor> with an entityID that matches the Elasticsearch configuration
  • An <IDPSSODescriptor> that supports the SAML 2.0 protocol (urn:oasis:names:tc:SAML:2.0:protocol).
  • At least one <KeyDescriptor> that is configured for signing (that is, it has use="signing" or leaves the use unspecified)
  • A <SingleSignOnService> with binding of HTTP-Redirect (urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect)
  • If you wish to support Single Logout, a <SingleLogoutService> with binding of HTTP-Redirect (urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect)

The Elastic Stack requires that all messages from the IdP are signed. For authentication <Response> messages, the signature may be applied to either the response itself, or to the individual assertions. For <LogoutRequest> messages, the message itself must be signed, and the signature should be provided as a URL parameter, as required by the HTTP-Redirect binding.

Configure Elasticsearch for SAML authenticationedit

There are five configuration steps to enable SAML authentication in Elasticsearch:

  1. Enable SSL/TLS for HTTP
  2. Enable the Token Service
  3. Create one or more SAML realms
  4. Configure role mappings
  5. Generate a SAML Metadata file for use by your Identity Provider (optional)

Enable TLS for HTTPedit

If your Elasticsearch cluster is operating in production mode, then you must configure the HTTP interface to use SSL/TLS before you can enable SAML authentication.

For more information, see Encrypt HTTP client communications for Elasticsearch.

Enable the token serviceedit

The Elasticsearch SAML implementation makes use of the Elasticsearch Token Service. This service is automatically enabled if you configure TLS on the HTTP interface, and can be explicitly configured by including the following in your elasticsearch.yml file:

xpack.security.authc.token.enabled: true

Create a SAML realmedit

SAML authentication is enabled by configuring a SAML realm within the authentication chain for Elasticsearch.

This realm has a few mandatory settings, and a number of optional settings. The available settings are described in detail in Security settings. For example, SAML realm settings, SAML realm signing settings, SAML realm encryption settings, SAML realm SSL settings. This guide will walk you through the most common settings.

Create a realm by adding the following to your elasticsearch.yml configuration file. Each configuration value is explained below.

xpack.security.authc.realms.saml.saml1:
  order: 2
  idp.metadata.path: saml/idp-metadata.xml
  idp.entity_id: "https://sso.example.com/"
  sp.entity_id:  "https://kibana.example.com/"
  sp.acs: "https://kibana.example.com/api/security/saml/callback"
  sp.logout: "https://kibana.example.com/logout"
  attributes.principal: "urn:oid:0.9.2342.19200300.100.1.1"
  attributes.groups: "urn:oid:1.3.6.1.4.1.5923.1.5.1."

SAML is used when authenticating via Kibana, but it is not an effective means of authenticating directly to the Elasticsearch REST API. For this reason we recommend that you include at least one additional realm such as the native realm in your authentication chain for use by API clients.

The configuration values used in the example above are:

xpack.security.authc.realms.saml.saml1
This defines a new saml authentication realm named "saml1". See Realms for more explanation of realms.
order
The order of the realm within the realm chain. Realms with a lower order have highest priority and are consulted first. We recommend giving password-based realms such as file, native, LDAP, and Active Directory the lowest order (highest priority), followed by SSO realms such as SAML and OpenID Connect. If you have multiple realms of the same type, give the most frequently accessed realm the lowest order to have it consulted first.
idp.metadata.path
This is the path to the metadata file that you saved for your Identity Provider. The path that you enter here is relative to your config/ directory. Elasticsearch will automatically monitor this file for changes and will reload the configuration whenever it is updated.
idp.entity_id
This is the identifier (SAML EntityID) that your IdP uses. It should match the entityID attribute within the metadata file.
sp.entity_id
This is a unique identifier for your Kibana instance, expressed as a URI. You will use this value when you add Kibana as a service provider within your IdP. We recommend that you use the base URL for your Kibana instance as the entity ID.
sp.acs
The Assertion Consumer Service (ACS) endpoint is the URL within Kibana that accepts authentication messages from the IdP. This ACS endpoint supports the SAML HTTP-POST binding only. It must be a URL that is accessible from the web browser of the user who is attempting to login to Kibana, it does not need to be directly accessible by Elasticsearch or the IdP. The correct value may vary depending on how you have installed Kibana and whether there are any proxies involved, but it will typically be ${kibana-url}/api/security/saml/callback where ${kibana-url} is the base URL for your Kibana instance.
sp.logout
This is the URL within Kibana that accepts logout messages from the IdP. Like the sp.acs URL, it must be accessible from the web browser, but does not need to be directly accessible by Elasticsearch or the IdP. The correct value may vary depending on how you have installed Kibana and whether there are any proxies involved, but it will typically be ${kibana-url}/logout where ${kibana-url} is the base URL for your Kibana instance.
attribute.principal
See Attribute mapping.
attribute.groups
See Attribute mapping.

Attribute mappingedit

When a user connects to Kibana through your Identity Provider, the Identity Provider will supply a SAML Assertion about the user. The assertion will contain an Authentication Statement indicating that the user has successfully authenticated to the IdP and one or more Attribute Statements that will include Attributes for the user.

These attributes may include such things as:

  • the user’s username
  • the user’s email address
  • the user’s groups or roles

Attributes in SAML are named using a URI such as urn:oid:0.9.2342.19200300.100.1.1 or http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn, and have one or more values associated with them.

These attribute identifiers vary between IdPs, and most IdPs offer ways to customize the URIs and their associated value.

Elasticsearch uses these attributes to infer information about the user who has logged in, and they can be used for role mapping (below).

In order for these attributes to be useful, Elasticsearch and the IdP need to have a common value for the names of the attributes. This is done manually, by configuring the IdP and the SAML realm to use the same URI name for each logical user attribute.

The recommended steps for configuring these SAML attributes are as follows:

  1. Consult your IdP to see what user attributes it can provide. This varies greatly between providers, but you should be able to obtain a list from the documentation, or from your local admin.
  2. Read through the list of user properties that Elasticsearch supports, and decide which of them are useful to you, and can be provided by your IdP. At a minimum, the principal attribute is required.
  3. Configure your IdP to "release" those attributes to your Kibana SAML service provider. This process varies by provider - some will provide a user interface for this, while others may require that you edit configuration files. Usually the IdP (or your local administrator) will have suggestions about what URI to use for each attribute. You can simply accept those suggestions, as the Elasticsearch service is entirely configurable and does not require that any specific URIs are used.
  4. Configure the SAML realm in Elasticsearch to associate the Elasticsearch user properties (see the listing below), to the URIs that you configured in your IdP. In the example above, we have configured the principal and groups attributes.
Special attribute namesedit

In general, Elasticsearch expects that the configured value for an attribute will be a URI such as urn:oid:0.9.2342.19200300.100.1.1, however there are some additional names that can be used:

nameid
This uses the SAML NameID value instead of a SAML attribute. SAML NameID elements are an optional, but frequently provided, field within a SAML Assertion that the IdP may use to identify the Subject of that Assertion. In some cases the NameID will relate to the user’s login identifier (username) within the IdP, but in many cases they will be internally generated identifiers that have no obvious meaning outside of the IdP.
nameid:persistent
This uses the SAML NameID value, but only if the NameID format is urn:oasis:names:tc:SAML:2.0:nameid-format:persistent. A SAML NameID element has an optional Format attribute that indicates the semantics of the provided name. It is common for IdPs to be configured with "transient" NameIDs that present a new identifier for each session. Since it is rarely useful to use a transient NameID as part of an attribute mapping, the "nameid:persistent" attribute name can be used as a safety mechanism that will cause an error if you attempt to map from a NameID that does not have a persistent value.

Identity Providers can be either statically configured to release a NameID with a specific format, or they can be configured to try to conform with the requirements of the SP. The SP declares its requirements as part of the Authentication Request, using an element which is called the NameIDPolicy. If this is needed, you can set the relevant settings named nameid_format in order to request that the IdP releases a NameID with a specific format.

friendlyName
A SAML attribute may have a friendlyName in addition to its URI based name. For example the attribute with a name of urn:oid:0.9.2342.19200300.100.1.1 might also have a friendlyName of uid. You may use these friendly names within an attribute mapping, but it is recommended that you use the URI based names, as friendlyNames are neither standardized or mandatory.

The example below configures a realm to use a persistent nameid for the principal, and the attribute with the friendlyName "roles" for the user’s groups.

xpack.security.authc.realms.saml.saml1:
  order: 2
  idp.metadata.path: saml/idp-metadata.xml
  idp.entity_id: "https://sso.example.com/"
  sp.entity_id:  "https://kibana.example.com/"
  sp.acs: "https://kibana.example.com/api/security/saml/callback"
  attributes.principal: "nameid:persistent"
  attributes.groups: "roles"
  nameid_format: "urn:oasis:names:tc:SAML:2.0:nameid-format:persistent"
Elasticsearch user propertiesedit

The Elasticsearch SAML realm can be configured to map SAML attributes to the following properties on the authenticated user:

principal
(Required) This is the username that will be applied to a user that authenticates against this realm. The principal appears in places such as the Elasticsearch audit logs.
groups
(Recommended) If you wish to use your IdP’s concept of groups or roles as the basis for a user’s Elasticsearch privileges, you should map them with this attribute. The groups are passed directly to your role mapping rules
name
(Optional) The user’s full name.
mail
(Optional) The user’s email address.
dn
(Optional) The user’s X.500 Distinguished Name.
Extracting partial values from SAML attributesedit

There are some occasions where the IdP’s attribute may contain more information than you wish to use within Elasticsearch. A common example of this is one where the IdP works exclusively with email addresses, but you would like the user’s principal to use the local-name part of the email address. For example if their email address was james.wong@staff.example.com, then you would like their principal to simply be james.wong.

This can be achieved using the attribute_patterns setting in the Elasticsearch realm, as demonstrated in the realm configuration below:

xpack.security.authc.realms.saml.saml1:
  order: 2
  idp.metadata.path: saml/idp-metadata.xml
  idp.entity_id: "https://sso.example.com/"
  sp.entity_id:  "https://kibana.example.com/"
  sp.acs: "https://kibana.example.com/api/security/saml/callback"
  attributes.principal: "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress"
  attribute_patterns.principal: "^([^@]+)@staff\\.example\\.com$"

In this case, the user’s principal is mapped from an email attribute, but a regular expression is applied to the value before it is assigned to the user. If the regular expression matches, then the result of the first group is used as effective value. If the regular expression does not match then the attribute mapping fails.

In this example, the email address must belong to the staff.example.com domain, and then the local-part (anything before the @) is used as the principal. Any users who try to login using a different email domain will fail because the regular expression will not match against their email address, and thus their principal attribute - which is mandatory - will not be populated.

Small mistakes in these regular expressions can have significant security consequences. For example, if we accidentally left off the trailing $ from the example above, then we would match any email address where the domain starts with staff.example.com, and this would accept an email address such as admin@staff.example.com.attacker.net. It is important that you make sure your regular expressions are as precise as possible so that you do not inadvertently open an avenue for user impersonation attacks.

Requesting specific authentication methodsedit

It is sometimes necessary for a SAML SP to be able to impose specific restrictions regarding the authentication that will take place at an IdP, in order to assess the level of confidence that it can place in the corresponding authentication response. The restrictions might have to do with the authentication method (password, client certificates, etc), the user identification method during registration, and other details. Elasticsearch implements SAML 2.0 Authentication Context, which can be used for this purpose as defined in SAML 2.0 Core Specification.

In short, the SAML SP defines a set of Authentication Context Class Reference values, which describe the restrictions to be imposed on the IdP, and sends these in the Authentication Request. The IdP attempts to grant these restrictions. If it cannot grant them, the authentication attempt fails. If the user is successfully authenticated, the Authentication Statement of the SAML Response contains an indication of the restrictions that were satisfied.

You can define the Authentication Context Class Reference values by using the req_authn_context_class_ref option in the SAML realm configuration. See SAML realm settings.

Elasticsearch supports only the exact comparison method for the Authentication Context. When it receives the Authentication Response from the IdP, Elasticsearch examines the value of the Authentication Context Class Reference that is part of the Authentication Statement of the SAML Assertion. If it matches one of the requested values, the authentication is considered successful. Otherwise, the authentication attempt fails.

SAML logoutedit

The SAML protocol supports the concept of Single Logout (SLO). The level of support for SLO varies between Identity Providers. You should consult the documentation for your IdP to determine what Logout services it offers.

By default the Elastic Stack will support SAML SLO if the following are true:

  • Your IdP metadata specifies that the IdP offers a SLO service
  • Your IdP releases a NameID in the subject of the SAML assertion that it issues for your users
  • You configure sp.logout
  • The setting idp.use_single_logout is not false
IdP SLO serviceedit

One of the values that Elasticsearch reads from the IdP’s SAML metadata is the <SingleLogoutService>. In order for Single Logout to work with the Elastic stack, Elasticsearch requires that this exist and support a binding of urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect.

The Elastic Stack will send both <LogoutRequest> and <LogoutResponse> messages to this service as appropriate.

The sp.logout settingedit

The Elasticsearch realm setting sp.logout specifies a URL in Kibana to which the IdP can send both <LogoutRequest> and <LogoutResponse> messages. This service uses the SAML HTTP-Redirect binding.

Elasticsearch will process <LogoutRequest> messages, and perform a global signout that invalidates any existing Elasticsearch security tokens that are associated with the provided SAML session.

If you do not configure a value for sp.logout, Elasticsearch will refuse all <LogoutRequest> messages.

It is common for IdPs to require that LogoutRequest messages be signed, so you may need to configure signing credentials.

The idp.use_single_logout settingedit

If your IdP provides a <SingleLogoutService> but you do not wish to use it, you can configure idp.use_single_logout: false in your SAML realm, and Elasticsearch will ignore the SLO service that your IdP provides. In this case, when a user logs out of Kibana it will invalidate their Elasticsearch session (security token), but will not perform any logout at the IdP.

Using Kibana without single logoutedit

If your IdP does not support Single Logout, or you choose not to use it, then Kibana will perform a "local logout" only.

This means that Kibana will invalidate the session token it is using to communicate with Elasticsearch, but will not be able to perform any sort of invalidation of the Identity Provider session. In most cases this will mean that Kibana users are still considered to be logged in to the IdP. Consequently, if the user navigates to the Kibana landing page, they will be automatically reauthenticated, and will commence a new Kibana session without needing to enter any credentials.

The possible solutions to this problem are:

  • Ask your IdP administrator or vendor to provide a Single Logout service
  • If your Idp does provide a Single Logout Service, make sure it is included in the IdP metadata file, and do not set idp.use_single_logout to false.
  • Advise your users to close their browser after logging out of Kibana
  • Enable the force_authn setting on your SAML realm. This setting causes the Elastic Stack to request fresh authentication from the IdP every time a user attempts to log in to Kibana. This setting defaults to false because it can be a more cumbersome user experience, but it can also be an effective protection to stop users piggy-backing on existing IdP sessions.

Encryption and signingedit

The Elastic Stack supports generating signed SAML messages (for authentication and/or logout), verifying signed SAML messages from the IdP (for both authentication and logout) and can process encrypted content.

You can configure Elasticsearch for signing, encryption or both, with the same or separate keys used for each of those.

The Elastic Stack uses X.509 certificates with RSA private keys for SAML cryptography. These keys can be generated using any standard SSL tool, including the elasticsearch-certutil tool.

Your IdP may require that the Elastic Stack have a cryptographic key for signing SAML messages, and that you provide the corresponding signing certificate within the Service Provider configuration (either within the Elastic Stack SAML metadata file or manually configured within the IdP administration interface). While most IdPs do not expected authentication requests to be signed, it is commonly the case that signatures are required for logout requests. Your IdP will validate these signatures against the signing certificate that has been configured for the Elastic Stack Service Provider.

Encryption certificates are rarely needed, but the Elastic Stack supports them for cases where IdPs or local policies mandate their use.

Generating certificates and keysedit

Elasticsearch supports certificates and keys in either PEM, PKCS#12 or JKS format. Some Identity Providers are more restrictive in the formats they support, and will require you to provide the certificates as a file in a particular format. You should consult the documentation for your IdP to determine what formats they support. Since PEM format is the most commonly supported format, the examples below will generate certificates in that format.

Using the elasticsearch-certutil tool, you can generate a signing certificate with the following command:

bin/elasticsearch-certutil cert --self-signed --pem --days 1100 --name saml-sign --out saml-sign.zip

This will

  • generate a certificate and key pair (the cert subcommand)
  • create the files in PEM format (-pem option)
  • generate a certificate that is valid for 3 years (-days 1100)
  • name the certificate saml-sign (-name option)
  • save the certificate and key in the saml-sign.zip file (-out option)

The generated zip archive will contain 3 files:

  • saml-sign.crt, the public certificate to be used for signing
  • saml-sign.key, the private key for the certificate
  • ca.crt, a CA certificate that is not need, and can be ignored.

Encryption certificates can be generated with the same process.

Configuring Elasticsearch for signingedit

By default, Elasticsearch will sign all outgoing SAML messages if a signing key has been configured.

If you wish to use PEM formatted keys and certificates for signing, then you should configure the following settings on the SAML realm:

signing.certificate
The path to the PEM formatted certificate file. e.g. saml/saml-sign.crt
signing.key
The path to the PEM formatted key file. e.g. saml/saml-sign.key
signing.secure_key_passphrase
The passphrase for the key, if the file is encrypted. This is a secure setting that must be set with the elasticsearch-keystore tool.

If you wish to use PKCS#12 formatted files or a Java Keystore for signing, then you should configure the following settings on the SAML realm:

signing.keystore.path
The path to the PKCS#12 or JKS keystore. e.g. saml/saml-sign.p12
signing.keystore.alias
The alias of the key within the keystore. e.g. signing-key
signing.keystore.secure_password
The passphrase for the keystore, if the file is encrypted. This is a secure setting that must be set with the elasticsearch-keystore tool.

If you wish to sign some, but not all outgoing SAML messages, then you should configure the following setting on the SAML realm:

signing.saml_messages
A list of message types to sign. A message type is identified by the local name of the XML element used for the message. Supported values are: AuthnRequest, LogoutRequest and LogoutResponse.
Configuring Elasticsearch for encrypted messagesedit

The Elasticsearch security features support a single key for message decryption. If a key is configured, then Elasticsearch attempts to use it to decrypt EncryptedAssertion and EncryptedAttribute elements in Authentication responses, and EncryptedID elements in Logout requests.

Elasticsearch rejects any SAML message that contains an EncryptedAssertion that cannot be decrypted.

If an Assertion contains both encrypted and plain-text attributes, then failure to decrypt the encrypted attributes will not cause an automatic rejection. Rather, Elasticsearch processes the available plain-text attributes (and any EncryptedAttributes that could be decrypted).

If you wish to use PEM formatted keys and certificates for SAML encryption, then you should configure the following settings on the SAML realm:

encryption.certificate
The path to the PEM formatted certificate file. e.g. saml/saml-crypt.crt
encryption.key
The path to the PEM formatted key file. e.g. saml/saml-crypt.key
encryption.secure_key_passphrase
The passphrase for the key, if the file is encrypted. This is a secure setting that must be set with the elasticsearch-keystore tool.

If you wish to use PKCS#12 formatted files or a Java Keystore for SAML encryption, then you should configure the following settings on the SAML realm:

encryption.keystore.path
The path to the PKCS#12 or JKS keystore. e.g. saml/saml-crypt.p12
encryption.keystore.alias
The alias of the key within the keystore. e.g. encryption-key
encryption.keystore.secure_password
The passphrase for the keystore, if the file is encrypted. This is a secure setting that must be set with the elasticsearch-keystore tool.

Generating SP metadataedit

Some Identity Providers support importing a metadata file from the Service Provider. This will automatically configure many of the integration options between the IdP and the SP.

The Elastic Stack supports generating such a metadata file using the bin/elasticsearch-saml-metadata command or the SAML service provider metadata API.

You can generate the SAML metadata by issuing the API request to Elasticsearch and store it as an XML file using tools like jq. For example, the following command generates the metadata for the SAML realm realm1 and saves it to a metadata.xml file:

curl -u user_name:password  -X GET http://localhost:9200/_security/saml/metadata/saml1 -H 'Content-Type: application/json' | jq -r '.[]' > metadata.xml

Configuring role mappingsedit

When a user authenticates using SAML, they are identified to the Elastic Stack, but this does not automatically grant them access to perform any actions or access any data.

Your SAML users cannot do anything until they are assigned roles. This can be done through either the add role mapping API or with authorization realms.

You cannot use role mapping files to grant roles to users authenticating via SAML.

This is an example of a simple role mapping that grants the example_role role to any user who authenticates against the saml1 realm:

PUT /_security/role_mapping/saml-example
{
  "roles": [ "example_role" ], 
  "enabled": true,
  "rules": {
    "field": { "realm.name": "saml1" }
  }
}

The example_role role is not a builtin Elasticsearch role. This example assumes that you have created a custom role of your own, with appropriate access to your data streams, indices, and Kibana features.

The attributes that are mapped via the realm configuration are used to process role mapping rules, and these rules determine which roles a user is granted.

The user fields that are provided to the role mapping are derived from the SAML attributes as follows:

  • username: The principal attribute
  • dn: The dn attribute
  • groups: The groups attribute
  • metadata: See User metadata

For more information, see Mapping users and groups to roles and Role mappings.

If your IdP has the ability to provide groups or roles to Service Providers, then you should map this SAML attribute to the attributes.groups setting in the Elasticsearch realm, and then make use of it in a role mapping as per the example below.

This mapping grants the Elasticsearch finance_data role, to any users who authenticate via the saml1 realm with the finance-team group.

PUT /_security/role_mapping/saml-finance
{
  "roles": [ "finance_data" ],
  "enabled": true,
  "rules": { "all": [
        { "field": { "realm.name": "saml1" } },
        { "field": { "groups": "finance-team" } }
  ] }
}

If your users also exist in a repository that can be directly accessed by Elasticsearch (such as an LDAP directory) then you can use authorization realms instead of role mappings.

In this case, you perform the following steps: 1. In your SAML realm, assigned a SAML attribute to act as the lookup userid, by configuring the attributes.principal setting. 2. Create a new realm that can lookup users from your local repository (e.g. an ldap realm) 3. In your SAML realm, set authorization_realms to the name of the realm you created in step 2.

User metadataedit

By default users who authenticate via SAML will have some additional metadata fields.

  • saml_nameid will be set to the value of the NameID element in the SAML authentication response
  • saml_nameid_format will be set to the full URI of the NameID’s format attribute
  • Every SAML Attribute that is provided in the authentication response (regardless of whether it is mapped to an Elasticsearch user property), will be added as the metadata field saml(name) where "name" is the full URI name of the attribute. For example saml(urn:oid:0.9.2342.19200300.100.1.3).
  • For every SAML Attribute that has a friendlyName, will also be added as the metadata field saml_friendlyName where "name" is the full URI name of the attribute. For example saml_mail.

This behaviour can be disabled by adding populate_user_metadata: false to as a setting in the saml realm.

Configuring Kibanaedit

SAML authentication in Kibana requires a small number of additional settings in addition to the standard Kibana security configuration. The Kibana security documentation provides details on the available configuration options that you can apply.

In particular, since your Elasticsearch nodes have been configured to use TLS on the HTTP interface, you must configure Kibana to use a https URL to connect to Elasticsearch, and you may need to configure elasticsearch.ssl.certificateAuthorities to trust the certificates that Elasticsearch has been configured to use.

SAML authentication in Kibana is subject to the following timeout settings in kibana.yml:

You may want to adjust these timeouts based on your security requirements.

The three additional settings that are required for SAML support are shown below:

xpack.security.authc.providers:
  saml.saml1:
    order: 0
    realm: "saml1"

The configuration values used in the example above are:

xpack.security.authc.providers
Add saml provider to instruct Kibana to use SAML SSO as the authentication method.
xpack.security.authc.providers.saml.<provider-name>.realm
Set this to the name of the SAML realm that you have used in your Elasticsearch realm configuration, for instance: saml1

Supporting SAML and basic authentication in Kibanaedit

The SAML support in Kibana is designed on the expectation that it will be the primary (or sole) authentication method for users of that Kibana instance. However, it is possible to support both SAML and Basic authentication within a single Kibana instance by setting xpack.security.authc.providers as per the example below:

xpack.security.authc.providers:
  saml.saml1:
    order: 0
    realm: "saml1"
  basic.basic1:
    order: 1

If Kibana is configured in this way, users are presented with a choice at the Login Selector UI. They log in with SAML or they provide a username and password and rely on one of the other security realms within Elasticsearch. Only users who have a username and password for a configured Elasticsearch authentication realm can log in via Kibana login form.

Alternatively, when the basic authentication provider is enabled, you can place a reverse proxy in front of Kibana, and configure it to send a basic authentication header (Authorization: Basic ....) for each request. If this header is present and valid, Kibana will not initiate the SAML authentication process.

Operating multiple Kibana instancesedit

If you wish to have multiple Kibana instances that authenticate against the same Elasticsearch cluster, then each Kibana instance that is configured for SAML authentication, requires its own SAML realm.

Each SAML realm must have its own unique Entity ID (sp.entity_id), and its own Assertion Consumer Service (sp.acs). Each Kibana instance will be mapped to the correct realm by looking up the matching sp.acs value.

These realms may use the same Identity Provider, but are not required to.

The following is example of having 3 difference Kibana instances, 2 of which use the same internal IdP, and another which uses a different IdP.

xpack.security.authc.realms.saml.saml_finance:
  order: 2
  idp.metadata.path: saml/idp-metadata.xml
  idp.entity_id: "https://sso.example.com/"
  sp.entity_id:  "https://kibana.finance.example.com/"
  sp.acs: "https://kibana.finance.example.com/api/security/saml/callback"
  sp.logout: "https://kibana.finance.example.com/logout"
  attributes.principal: "urn:oid:0.9.2342.19200300.100.1.1"
  attributes.groups: "urn:oid:1.3.6.1.4.1.5923.1.5.1."
xpack.security.authc.realms.saml.saml_sales:
  order: 3
  idp.metadata.path: saml/idp-metadata.xml
  idp.entity_id: "https://sso.example.com/"
  sp.entity_id:  "https://kibana.sales.example.com/"
  sp.acs: "https://kibana.sales.example.com/api/security/saml/callback"
  sp.logout: "https://kibana.sales.example.com/logout"
  attributes.principal: "urn:oid:0.9.2342.19200300.100.1.1"
  attributes.groups: "urn:oid:1.3.6.1.4.1.5923.1.5.1."
xpack.security.authc.realms.saml.saml_eng:
  order: 4
  idp.metadata.path: saml/idp-external.xml
  idp.entity_id: "https://engineering.sso.example.net/"
  sp.entity_id:  "https://kibana.engineering.example.com/"
  sp.acs: "https://kibana.engineering.example.com/api/security/saml/callback"
  sp.logout: "https://kibana.engineering.example.com/logout"
  attributes.principal: "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn"

It is possible to have one or more Kibana instances that use SAML, while other instances use basic authentication against another realm type (e.g. Native or LDAP).

Troubleshooting SAML Realm Configurationedit

The SAML 2.0 specification offers a lot of options and flexibility for the implementers of the standard which in turn adds to the complexity and the number of configuration options that are available both at the Service Provider (Elastic Stack) and at the Identity Provider. Additionally, different security domains have different security requirements that need specific configuration to be satisfied. A conscious effort has been made to mask this complexity with sane defaults and the detailed documentation above but in case you encounter issues while configuring a SAML realm, you can look through our SAML troubleshooting documentation that has suggestions and resolutions for common issues.

SAML without Kibanaedit

The SAML realm in Elasticsearch is designed to allow users to authenticate to Kibana and as such, most of the parts of the guide above make the assumption that Kibana is used. This section describes how a custom web application could use the relevant SAML REST APIs in order to authenticate the users to Elasticsearch with SAML.

This section assumes that the reader is familiar with the SAML 2.0 standard and more specifically with the SAML 2.0 Web Browser Single Sign On profile.

Single sign-on realms such as OpenID Connect and SAML make use of the Token Service in Elasticsearch and in principle exchange a SAML or OpenID Connect Authentication response for an Elasticsearch access token and a refresh token. The access token is used as credentials for subsequent calls to Elasticsearch. The refresh token enables the user to get new Elasticsearch access tokens after the current one expires.

SAML realmedit

You must create a SAML realm and configure it accordingly in Elasticsearch. See Configure Elasticsearch for SAML authentication

Service Account user for accessing the APIsedit

The realm is designed with the assumption that there needs to be a privileged entity acting as an authentication proxy. In this case, the custom web application is the authentication proxy handling the authentication of end users (more correctly, "delegating" the authentication to the SAML Identity Provider). The SAML related APIs require authentication and the necessary authorization level for the authenticated user. For this reason, you must create a Service Account user and assign it a role that gives it the manage_saml cluster privilege. The use of the manage_token cluster privilege will be necessary after the authentication takes place, so that the service account user can maintain access in order refresh access tokens on behalf of the authenticated users or to subsequently log them out.

POST /_security/role/saml-service-role
{
  "cluster" : ["manage_saml", "manage_token"]
}
POST /_security/user/saml-service-user
{
  "password" : "<somePasswordHere>",
  "roles"    : ["saml-service-role"]
}

Handling the SP-initiated authentication flowedit

On a high level, the custom web application would need to perform the following steps in order to authenticate a user with SAML against Elasticsearch:

  1. Make an HTTP POST request to _security/saml/prepare, authenticating as the saml-service-user user. Use either the name of the SAML realm in the Elasticsearch configuration or the value for the Assertion Consumer Service URL in the request body. See the SAML prepare authentication API for more details.

    POST /_security/saml/prepare
    {
      "realm" : "saml1"
    }
  2. Handle the response from /_security/saml/prepare. The response from Elasticsearch will contain 3 parameters: redirect, realm and id. The custom web application would need to store the value for id in the user’s session (client side in a cookie or server side if session information is persisted this way). It must also redirect the user’s browser to the URL that was returned in the redirect parameter. The id value should not be disregarded as it is used as a nonce in SAML in order to mitigate against replay attacks.
  3. Handle a subsequent response from the SAML IdP. After the user is successfully authenticated with the Identity Provider they will be redirected back to the Assertion Consumer Service URL. This sp.acs needs to be defined as a URL which the custom web application handles. When it receives this HTTP POST request, the custom web application must parse it and make an HTTP POST request itself to the _security/saml/authenticate API. It must authenticate as the saml-service-user user and pass the Base64 encoded SAML Response that was sent as the body of the request. It must also pass the value for id that it had saved in the user’s session previously.

    See SAML authenticate API for more details.

    POST /_security/saml/authenticate
    {
      "content" : "PHNhbWxwOlJlc3BvbnNlIHhtbG5zOnNhbWxwPSJ1cm46b2FzaXM6bmFtZXM6dGM6U0FNTDoyLjA6cHJvdG9jb2wiIHhtbG5zOnNhbWw9InVybjpvYXNpczpuYW1lczp0YzpTQU1MOjIuMD.....",
      "ids" : ["4fee3b046395c4e751011e97f8900b5273d56685"]
    }

    Elasticsearch will validate this and if all is correct will respond with an access token that can be used as a Bearer token for subsequent requests. It also supplies a refresh token that can be later used to refresh the given access token as described in get token API.

  4. The response to calling /_security/saml/authenticate will contain only the username of the authenticated user. If you need to get the values for the SAML Attributes that were contained in the SAML Response for that user, you can call the Authenticate API /_security/_authenticate/ using the access token as a Bearer token and the SAML attribute values will be contained in the response as part of the User metadata.

Handling the IdP-initiated authentication flowedit

Elasticsearch can also handle the IdP-initiated Single Sign On flow of the SAML 2 Web Browser SSO profile. In this case the authentication starts with an unsolicited authentication response from the SAML Identity Provider. The difference with the SP initiated SSO is that the web application needs to handle requests to the sp.acs that will not come as responses to previous redirections. As such, it will not have a session for the user already, and it will not have any stored values for the id parameter. The request to the _security/saml/authenticate API will look like the one below in this case:

POST /_security/saml/authenticate
{
  "content" : "PHNhbWxwOlJlc3BvbnNlIHhtbG5zOnNhbWxwPSJ1cm46b2FzaXM6bmFtZXM6dGM6U0FNTDoyLjA6cHJvdG9jb2wiIHhtbG5zOnNhbWw9InVybjpvYXNpczpuYW1lczp0YzpTQU1MOjIuMD.....",
  "ids" : []
}

Handling the logout flowedit

  1. At some point, if necessary, the custom web application can log the user out by using the SAML logout API and passing the access token and refresh token as parameters. For example:

    POST /_security/saml/logout
    {
      "token" : "46ToAxZVaXVVZTVKOVF5YU04ZFJVUDVSZlV3",
      "refresh_token": "mJdXLtmvTUSpoLwMvdBt_w"
    }

    If the SAML realm is configured accordingly and the IdP supports it (see SAML logout), this request will trigger a SAML SP-initiated Single Logout. In this case, the response will include a redirect parameter indicating where the user needs to be redirected at the IdP in order to complete the logout.

  2. Alternatively, the IdP might initiate the Single Logout flow at some point. In order to handle this, the Logout URL (sp.logout) needs to be handled by the custom web app. The query part of the URL that the user will be redirected to will contain a SAML Logout request and this query part needs to be relayed to Elasticsearch using the SAML invalidate API

    POST /_security/saml/invalidate
    {
      "query" : "SAMLRequest=nZFda4MwFIb%2FiuS%2BmviRpqFaClKQdbvo2g12M2KMraCJ9cRR9utnW4Wyi13sMie873MeznJ1aWrnS3VQGR0j4mLkKC1NUeljjA77zYyhVbIE0dR%2By7fmaHq7U%2BdegXWGpAZ%2B%2F4pR32luBFTAtWgUcCv56%2Fp5y30X87Yz1khTIycdgpUW9kY7WdsC9zxoXTvMvWuVV98YyMnSGH2SYE5pwALBIr9QKiwDGpW0oGVUznGeMyJZKFkQ4jBf5HnhUymjIhzCAL3KNFihbYx8TBYzzGaY7EnIyZwHzCWMfiDnbRIftkSjJr%2BFu0e9v%2B0EgOquRiiZjKpiVFp6j50T4WXoyNJ%2FEWC9fdqc1t%2F1%2B2F3aUpjzhPiXpqMz1%2FHSn4A&SigAlg=http%3A%2F%2Fwww.w3.org%2F2001%2F04%2Fxmldsig-more%23rsa-sha256&Signature=MsAYz2NFdovMG2mXf6TSpu5vlQQyEJAg%2B4KCwBqJTmrb3yGXKUtIgvjqf88eCAK32v3eN8vupjPC8LglYmke1ZnjK0%2FKxzkvSjTVA7mMQe2AQdKbkyC038zzRq%2FYHcjFDE%2Bz0qISwSHZY2NyLePmwU7SexEXnIz37jKC6NMEhus%3D",
      "realm" : "saml1"
    }

    The custom web application will then need to also handle the response, which will include a redirect parameter with a URL in the IdP that contains the SAML Logout response. The application should redirect the user there to complete the logout.

For SP-initiated Single Logout, the IdP may send back a logout response which can be verified by Elasticsearch using the SAML complete logout API.