CVE-2015-1638 in Windows
Summary
by MITRE
Microsoft Active Directory Federation Services (AD FS) 3.0 on Windows Server 2012 R2 does not properly handle logoff actions, which allows remote attackers to bypass intended access restrictions by leveraging an unattended workstation, aka "Active Directory Federation Services Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability identified as CVE-2015-1638 resides within Microsoft Active Directory Federation Services version 3.0 running on Windows Server 2012 R2 systems. This flaw represents a critical security weakness in the authentication and authorization framework that governs federated identity management within enterprise environments. The vulnerability specifically manifests in the improper handling of logoff operations within the AD FS infrastructure, creating a significant bypass mechanism that undermines the intended security controls designed to protect authenticated sessions and access permissions.
The technical nature of this vulnerability stems from insufficient validation and handling of session termination processes within the AD FS component. When users log off from federated systems, the proper behavior should invalidate all associated authentication tokens and session identifiers to prevent unauthorized access. However, this vulnerability allows attackers to exploit the gap in logoff handling, enabling them to maintain access to resources and information that should have been restricted upon session termination. The flaw particularly affects unattended workstations where users have logged off but left systems operational, creating an attack surface that adversaries can leverage without requiring additional authentication credentials.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally compromises the security model of federated identity systems. Attackers can exploit this weakness to access sensitive data, perform unauthorized operations, and potentially escalate privileges within the federated environment. The vulnerability's classification as an information disclosure issue means that unauthorized parties can gain access to resources that should be restricted to authenticated users only, potentially exposing confidential organizational data, privileged information, or system resources that are part of the federated access control framework. This weakness directly violates the principle of least privilege and can lead to significant data breaches and unauthorized system access.
This vulnerability aligns with CWE-284, which addresses improper access control mechanisms, and relates to ATT&CK technique T1078.004 for valid accounts and T1566 for credential harvesting through social engineering or system exploitation. Organizations implementing AD FS services face particular risk as this flaw can be exploited remotely without requiring physical access to systems, making it a significant concern for enterprise security. The attack vector specifically targets unattended workstations where users have logged off, creating a scenario where the system's security controls fail to properly enforce access restrictions. Security professionals should consider this vulnerability as part of broader identity and access management assessments, particularly in environments relying heavily on federated authentication systems.
Mitigation strategies for CVE-2015-1638 should include immediate deployment of Microsoft security patches and updates to address the logoff handling flaw in AD FS components. Organizations must also implement additional monitoring and detection mechanisms to identify unauthorized access attempts that may exploit this vulnerability. Network segmentation and access control measures should be enhanced to limit the potential impact of successful exploitation. Security teams should conduct comprehensive assessments of their federated identity environments to identify similar vulnerabilities and ensure proper session management controls are in place. Regular security audits and vulnerability assessments should include specific checks for proper logoff and session termination handling within authentication systems. Additionally, organizations should implement robust logging and monitoring of authentication events to detect anomalous behavior that might indicate exploitation attempts. The remediation process requires careful coordination between system administrators and security teams to ensure that all affected AD FS servers receive appropriate updates while maintaining service availability and minimizing disruption to legitimate user access.