AspNetCore Remote Authenticator for CIE3.0 は SAML レスポンスの署名検証のバイパスを許可する

The core of this vulnerability lies in the misconfiguration or flawed implementation of SAML2 authentication within applications utilizing CIE.AspNetCore.Authentication. An attacker can craft malicious SAML assertions, manipulating identity information to impersonate legitimate users or gain access without proper credentials. This could lead to complete compromise of the application and its underlying data. Successful exploitation could result in unauthorized data access, modification, or deletion, as well as the ability to execute arbitrary code on the server, depending on the application's overall security posture. The impact is amplified if the application handles sensitive data or integrates with other critical systems.

Applications built using ASP.NET Core and relying on CIE.AspNetCore.Authentication for SAML-based authentication are at risk. This includes organizations using Single Sign-On (SSO) solutions and federated identity management systems. Legacy applications with outdated dependencies are particularly vulnerable.

• .NET / ASP.NET Core: Examine application logs for unusual SAML assertion patterns or authentication failures. Use a debugger to trace the SAML assertion processing flow and identify potential vulnerabilities. • .NET / ASP.NET Core: Monitor for unexpected user access patterns or privilege escalations. • Generic Web: Inspect SAML request/response payloads for malformed or unexpected attributes using a proxy like Burp Suite or OWASP ZAP.

1. 2025-02-18Disclosure

   disclosure

1. 予約済み2025-01-27
2. 公開日2025-02-18
3. EPSS 更新日2026-04-02

The primary mitigation is to immediately upgrade to CIE.AspNetCore.Authentication version 2.1.0 or later, which addresses the vulnerability. If upgrading is not immediately feasible, consider implementing temporary workarounds. Thoroughly review and validate all SAML configurations, ensuring proper assertion validation and attribute mapping. Implement strict access controls and multi-factor authentication to limit the potential damage from a successful attack. Consider using a Web Application Firewall (WAF) with SAML inspection capabilities to detect and block malicious assertions. Regularly audit SAML configurations and logs for suspicious activity.