Open Redirect in Apache Syncope via CAS Authentication

Executive Summary

This is an Open Redirect vulnerability in Apache Syncope. When configured for CAS authentication, the system uses client-supplied forwarded HTTP headers to calculate the target CAS instance URL without validation. This allows attackers to manipulate the URL and redirect users to untrusted sites.

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Detection Guidance

To detect this vulnerability, check if your Apache Syncope instance is configured for CAS authentication and verify if it unconditionally trusts client-supplied forwarded HTTP headers for URL calculation. Inspect network traffic for unexpected redirects to untrusted domains.

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Impact Analysis

Attackers could trick users into visiting malicious sites by redirecting them from a trusted Apache Syncope domain. This may lead to phishing attacks, credential theft, or malware distribution. Users with administrative access are particularly at risk.

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Compliance Impact

This vulnerability allows URL redirection to untrusted sites, which could be exploited for phishing attacks. Such attacks may lead to unauthorized access to sensitive data, potentially violating GDPR (data protection) and HIPAA (health information privacy) compliance by exposing personal or health-related data.

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Mitigation Strategies

Upgrade Apache Syncope to version 4.0.8, 4.1.3, or later to fix the vulnerability. If using CAS authentication with Syncope SRA, ensure the target CAS instance URL is not derived from untrusted client-supplied headers.

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