Exercise 28: Exploiting Cloud Identity Federation Vulnerabilities

Objective:

Understand how vulnerabilities in cloud identity federation systems can be exploited to gain unauthorized access. Simulate an attack where weak federation settings, such as improperly configured trust policies or insecure token handling, allow an attacker to impersonate a legitimate user. Learn best practices to secure identity federation mechanisms.

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Scenario:

An organization uses a cloud identity federation system, such as AWS Cognito or Google Identity Platform, to allow users to log in with external identity providers (e.g., Google, Facebook, or SAML). Due to weak trust policies or token validation mechanisms, attackers exploit these vulnerabilities to impersonate legitimate users. Your goal is to demonstrate this scenario, highlight the risks, and suggest mitigations.

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Lab Setup:

Prerequisites:

1. Access to a cloud platform:
   • AWS Cognito or Google Identity Platform.
2. Installed tools:
   • OAuth 2.0 Client Tools (e.g., Postman or cURL).
   • jwt.io for decoding and analyzing tokens.

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Steps to Set Up the Lab:

1. Set Up an Identity Federation System:
   • AWS Cognito:
     1. Navigate to Cognito > Manage User Pools > Create a User Pool.
     2. Enable federation by allowing users to sign in with an external identity provider:
        • Choose Google or Facebook as an identity provider.
        • Configure the identity provider by providing the Client ID and Client Secret.
     3. Enable a custom domain for the Cognito-hosted UI.
   • Google Identity Platform:
     1. Go to APIs & Services > Credentials > Create Credentials.
     2. Create an OAuth 2.0 Client ID for a web application.
     3. Configure OAuth consent and enable federated login with other identity providers (e.g., Google, Facebook).
2. Create Weak Federation Settings:
   • Configure weak trust settings:
     • Accept tokens without verifying the signature.
     • Use a single static Redirect URI, allowing potential redirection to an attacker-controlled URL.
     • Allow excessive token expiration times (e.g., 7 days or longer).
3. Set Up a Vulnerable Application:
   • Build a simple web application that uses the federated identity system for authentication.
   • Host the application on a public URL (e.g., AWS Amplify, Firebase Hosting, or NGROK).

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Exercise: Exploiting Weak Federation Settings

Objective:

Simulate an attacker bypassing federation mechanisms and impersonating an authorized user.

1. Intercept OAuth Tokens:
   • Use Burp Suite or a proxy to intercept and modify the OAuth flow:
     • Login via the hosted UI or application.
     • Capture the OAuth token exchange between the browser and the identity provider.
   • Analyze the intercepted token using jwt.io.
2. Modify and Replay the Token:
   • Modify the token payload to impersonate another user by changing fields such as:jsonCopyEdit{ "sub": "victim-user-id", "email": "[email protected]", "roles": ["admin"] }
   • Bypass weak token validation (e.g., if the signature is not properly verified).
3. Exploit Redirect URI Vulnerabilities:
   • Manipulate the Redirect URI in the login request to point to an attacker-controlled server:bashCopyEdithttps://example.com/auth?redirect_uri=http://attacker.com/callback
   • Extract sensitive tokens from the redirection.
4. Impersonate a User:
   • Use the tampered token to gain access to the application as the victim user.
5. Test with Token Reuse:
   • Replay the same token to verify if the system properly enforces expiration or revocation.

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Tools Required:

1. AWS Cognito or Google Identity Platform: For setting up identity federation.
2. Burp Suite or Postman: For intercepting and modifying token requests.
3. jwt.io: For decoding and analyzing JWTs.
4. cURL: For simulating OAuth token requests and responses.

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Deliverables:

1. Exploit Report:
   • Evidence of intercepted and tampered tokens.
   • Logs or screenshots showing unauthorized access using the modified tokens.
   • Steps demonstrating how weak redirect URIs or token validation were exploited.
2. Recommendations for Securing Identity Federation:
   • Steps to configure secure trust policies, validate tokens, and enforce MFA.

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Solution:

1. Identified Vulnerabilities:
   • Weak Token Validation: Tokens were accepted without verifying the signature.
   • Insecure Redirect URIs: Allowed attackers to redirect tokens to malicious servers.
   • Excessive Token Expiry: Long-lived tokens increased the risk of misuse.
   • No MFA Enforcement: Login relied solely on passwords, making it easier to compromise accounts.
2. Consequences:
   • Unauthorized Access: Attackers impersonated users and gained access to sensitive resources.
   • Data Breach: Compromised user accounts exposed sensitive information.
   • Privilege Escalation: Attackers used tampered tokens to escalate privileges.
3. Prevention Techniques:
   • Implement Strong Token Validation:
     • Verify token signatures using the identity provider’s public key.
   • Enforce Redirect URI Whitelisting:
     • Allow only pre-approved redirect URIs to prevent token theft.
   • Limit Token Expiration:
     • Use short-lived tokens and implement refresh tokens for reauthentication.
   • Enable Multi-Factor Authentication (MFA):
     • Require MFA for all federated logins.
   • Monitor and Log Authentication Events:
     • Use AWS CloudTrail or Google Cloud Logging to detect unusual login activity.
   • Regularly Audit Trust Settings:
     • Review and update identity federation trust policies and configurations.

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Conclusion:

This exercise demonstrates how weak cloud identity federation settings can be exploited to impersonate users and bypass authentication mechanisms. By enforcing strong token validation, secure trust policies, and multi-factor authentication, organizations can significantly mitigate these risks.