Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a critical vulnerability in Cloud Foundry's User Account and Authentication (UAA) service. The issue allows for authentication bypass by improperly handling SAML assertions, where encryption was mistakenly accepted in place of required digital signatures. This could potentially allow unauthorized access to systems relying on UAA for identity verification.
- Unsigned but encrypted SAML data was accepted.
- Could bypass authentication for Cloud Foundry.
- Confirm relevance and potential exposure.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this by sending specially crafted SAML assertions to the Cloud Foundry User Account and Authentication (UAA) service. Since UAA incorrectly trusts encrypted assertions as authentic, an attacker could forge these assertions, bypassing authentication mechanisms and potentially gaining unauthorized access to resources.
- Requires network access to UAA.
- Attacker sends a forged SAML assertion.
- Risk of authentication bypass.
Live Threat
Current exploitation, exposure, and threat context
Cloud Foundry UAA could be tricked into accepting unsigned SAML assertions that contain encrypted content. This could allow an attacker to impersonate a user or service when `wantAssertionSigned` is set to `false` and the service provider relies on encryption for authenticity.
- User authentication data at risk.
- Impersonation via forged assertions.
- Unauthorized access to services.
Operational Fix
Recommended remediation, mitigation, and detection steps
In a Cloud Foundry environment, the platform or infrastructure teams are likely responsible for the User Account and Authentication (UAA) service. Initial triage should focus on confirming the deployment's exposure, identifying the specific UAA instances in use, and determining their criticality to business operations. Once these factors are understood, the accountable team can be engaged to plan the most appropriate remediation or mitigation strategy.
- Platform or infrastructure teams own the issue.
- Verify UAA instance reachability and business criticality.
- Plan remediation based on confirmed exposure.
