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Single Sign-Out SAML Protocol

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Microsoft Entra ID supports the SAML 2.0 web browser single sign-out profile. For single sign-out to work correctly, the LogoutURL for the application must be explicitly registered with Microsoft Entra ID during application registration.

If the app is added to the Azure App Gallery then this value can be set by default. Otherwise, the value must be determined and set by the person adding the app to their Microsoft Entra tenant. Microsoft Entra ID uses the LogoutURL to redirect users after they're signed out. Microsoft Entra ID supports redirect binding (HTTP GET), and not HTTP POST binding.

The following diagram shows the workflow of the Microsoft Entra single sign-out process.

Screenshot of the Microsoft Entra Single Sign Out Workflow.

LogoutRequest

The cloud service sends a LogoutRequest message to Microsoft Entra ID to indicate that a session has been terminated. The following excerpt shows a sample LogoutRequest element.

<samlp:LogoutRequest xmlns="urn:oasis:names:tc:SAML:2.0:metadata" ID="idaa6ebe6839094fe4abc4ebd5281ec780" Version="2.0" IssueInstant="2013-03-28T07:10:49.6004822Z" xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
  <Issuer xmlns="urn:oasis:names:tc:SAML:2.0:assertion">https://www.workaad.com</Issuer>
  <NameID xmlns="urn:oasis:names:tc:SAML:2.0:assertion"> Uz2Pqz1X7pxe4XLWxV9KJQ+n59d573SepSAkuYKSde8=</NameID>
</samlp:LogoutRequest>

The LogoutRequest element sent to Microsoft Entra ID requires the following attributes:

  • ID - This identifies the sign-out request. The value of ID shouldn't begin with a number. The typical practice is to append id to the string representation of a GUID.
  • Version - Set the value of this element to 2.0. This value is required.
  • IssueInstant - This is a DateTime string with a Coordinate Universal Time (UTC) value and round-trip format ("o"). Microsoft Entra ID expects a value of this type, but doesn't enforce it.

Per section 3.7 of the SAML 2.0 core specification, there can be multiple participants (other applications) in a session besides your application. If one of the other participants sends a LogoutRequest to the Microsoft identity platform (the session authority), it will send a LogoutRequest back to all the session participants except the participant who sent the initial LogoutRequest. If another participant simultaneously initiated sign-out, there would be a race to see which LogoutRequest reaches Microsoft identity platform first. Therefore, an application should always be prepared to handle a LogoutRequest.

Issuer

The Issuer element in a LogoutRequest must exactly match one of the ServicePrincipalNames in the cloud service in Microsoft Entra ID. Typically, this is set to the App ID URI that is specified during application registration.

NameID

The value of the NameID element must exactly match the NameID of the user that is being signed out.

Note

During SAML logout request, the NameID value is not considered by Microsoft Entra ID.
If a single user session is active, Microsoft Entra ID will automatically select that session and the SAML logout will proceed.
If multiple user sessions are active, Microsoft Entra ID will enumerate the active sessions for user selection. After user selection, the SAML logout will proceed.

LogoutResponse

Microsoft Entra ID sends a LogoutResponse in response to a LogoutRequest element. The following excerpt shows a sample LogoutResponse.

<samlp:LogoutResponse ID="_f0961a83-d071-4be5-a18c-9ae7b22987a4" Version="2.0" IssueInstant="2013-03-18T08:49:24.405Z" InResponseTo="iddce91f96e56747b5ace6d2e2aa9d4f8c" xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
  <Issuer xmlns="urn:oasis:names:tc:SAML:2.0:assertion">https://login.microsoftonline.com/aaaabbbb-0000-cccc-1111-dddd2222eeee/</Issuer>
  <samlp:Status>
    <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success" />
  </samlp:Status>
</samlp:LogoutResponse>

Microsoft Entra ID sets the ID, Version and IssueInstant values in the LogoutResponse element. It also sets the InResponseTo element to the value of the ID attribute of the LogoutRequest that elicited the response.

Issuer

Microsoft Entra ID sets this value to https://login.microsoftonline.com/<TenantIdGUID>/ where <TenantIdGUID> is the tenant ID of the Microsoft Entra tenant.

To correctly identify the issuer element, use the value https://login.microsoftonline.com/<TenantIdGUID>/ as shown in the sample LogoutResponse. This URL format identifies the Microsoft Entra tenant as the issuer, representing the authority responsible for issuing the response.

Status

Microsoft Entra ID uses the StatusCode element in the Status element to indicate the success or failure of sign-out. When the sign-out attempt fails, the StatusCode element can also contain custom error messages.