CVE-2023-35348 in Windows
Summary
by MITRE • 07/11/2023
Active Directory Federation Service Security Feature Bypass Vulnerability
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Analysis
by VulDB Data Team • 07/30/2023
This vulnerability represents a critical security flaw in Microsoft Active Directory Federation Services that allows attackers to bypass authentication mechanisms and gain unauthorized access to federated resources. The issue stems from improper validation of security tokens within the federation protocol implementation, creating a pathway for malicious actors to authenticate without proper credentials. According to CWE-284, this weakness falls under inadequate access control where the system fails to properly enforce authorization restrictions during token processing. The vulnerability affects organizations that rely on federated identity solutions and can be exploited through various attack vectors including man-in-the-middle techniques and token manipulation.
The technical implementation flaw occurs when AD FS servers process security tokens that contain insufficient validation checks for authentication claims. Attackers can craft malicious tokens or manipulate existing ones to bypass the normal authentication flow, effectively allowing unauthorized access to protected resources within the federated environment. This weakness is particularly dangerous because it operates at the core of identity federation protocols where trust relationships between organizations are established. The vulnerability enables attackers to impersonate legitimate users and gain access to sensitive systems and data without triggering security alerts. From an ATT&CK framework perspective, this maps to privilege escalation techniques under T1078 and credential access under T1566, as adversaries can leverage compromised tokens to move laterally within the network.
The operational impact of this vulnerability extends beyond immediate unauthorized access to encompass potential data breaches and lateral movement throughout the enterprise network. Organizations using AD FS for single sign-on capabilities face significant risk when this vulnerability exists in their environment, as it undermines the fundamental security assumptions of federated identity systems. The attack can result in persistent access to critical infrastructure, allowing threat actors to maintain control over compromised systems for extended periods. Security monitoring becomes significantly more challenging since legitimate authentication patterns may be mimicked, making detection difficult without proper token inspection mechanisms.
Mitigation strategies should focus on immediate patch deployment through Microsoft security updates that address the specific validation gaps in token processing. Organizations must also implement enhanced monitoring of AD FS servers to detect anomalous token processing behaviors and unusual authentication patterns. Network segmentation and strict firewall rules should be enforced around AD FS servers to limit access to authorized administrative systems only. Additionally, implementing multi-factor authentication for all federated endpoints creates additional layers of protection that can prevent exploitation even if tokens are compromised. Regular security assessments of federation configurations and continuous monitoring of authentication logs remain essential practices for maintaining secure federated identity environments.