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Automate SAML Login

G5 Cyber Security

TL;DR

This guide shows you how to automate SAML login for service users using a combination of scripting and tools like curl or PowerShell. This avoids manual logins, saving time and improving security.

Automating SAML Login

  1. Understand the Basics: SAML (Security Assertion Markup Language) lets users log in to multiple applications with one set of credentials. Automation requires understanding how your Identity Provider (IdP) handles requests and responses.
    • Service Principal: You’ll need a service principal or application registration within your IdP that represents the automated user.
    • API Access: Your script needs permission to interact with the IdP’s API (usually via an API key or certificate).
  2. Obtain SAML Request: The first step is getting a valid SAML request. This often involves sending a POST request to your service provider’s login endpoint. 
    curl -X POST 
     -H "Content-Type: application/x-www-form-urlencoded" 
     -d "RelayState=https://your-service-provider/some/url&SAMLRequest=YOUR_BASE64_ENCODED_REQUEST" 
     https://your-service-provider/login

    Replace YOUR_BASE64_ENCODED_REQUEST with the actual SAML request generated by your IdP. The exact method for generating this varies depending on your IdP (e.g., Azure AD, Okta).

  3. Authenticate and Get SAML Response: Once you have a SAML request, authenticate using your service principal.
    • Azure AD Example (PowerShell): This example uses the Invoke-RestMethod cmdlet to get an access token.
    $tenantId = "YOUR_TENANT_ID" 
$clientId = "YOUR_CLIENT_ID" 
$clientSecret = "YOUR_CLIENT_SECRET" 

$tokenEndpoint = "https://login.microsoftonline.com/$tenantId/oauth2/v2.0/token" 

$body = @{ 
  grant_type="client_credentials"; 
  client_id=$clientId; 
  client_secret=$clientSecret; 
  scope="YOUR_SCOPE" # e.g., "https://your-resource/.default" 
} 

$tokenResponse = Invoke-RestMethod -Uri $tokenEndpoint -Method POST -Body $body 
$accessToken = $tokenResponse.access_token
  4. Okta Example (curl): Use Okta’s API to obtain a token and then use that token to request the SAML response.

    Consult Okta’s documentation for specific API endpoints and parameters.

  5. Parse the SAML Response: The IdP will return a SAML response (usually as XML). You need to parse this response to extract the assertion.
    • XML Parsing Tools: Use tools like xmlstarlet or programming language libraries (e.g., Python’s lxml) to parse the XML. 
      xmlstarlet sel -t -v "/Assertion" response.xml
  6. Submit Assertion: Send the extracted SAML assertion back to your service provider, usually via a POST request. 
    curl -X POST 
     -H "Content-Type: application/x-www-form-urlencoded" 
     -d "SAMLResponse=YOUR_BASE64_ENCODED_ASSERTION&RelayState=https://your-service-provider/some/url" 
     https://your-service-provider/login

    Replace YOUR_BASE64_ENCODED_ASSERTION with the base64 encoded SAML assertion.

  7. Error Handling: Implement robust error handling to catch issues like invalid credentials, network errors, and malformed SAML responses.
    • Logging: Log all requests and responses for debugging purposes.
    • Retry Logic: Consider adding retry logic for transient errors.

Important Considerations:

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