CVE-2016-3226 in Windows
Summary
by MITRE
Active Directory in Microsoft Windows Server 2008 R2 SP1 and Server 2012 Gold and R2 allows remote authenticated users to cause a denial of service (service hang) by creating many machine accounts, aka "Active Directory Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 10/08/2024
The vulnerability identified as CVE-2016-3226 represents a critical denial of service weakness within Microsoft Active Directory services running on Windows Server 2008 R2 SP1 and Windows Server 2012 environments. This flaw specifically targets the directory service's handling of machine account creation processes, creating a scenario where authenticated attackers can systematically consume system resources through excessive account provisioning. The vulnerability operates at the core of Active Directory's account management infrastructure, where legitimate authentication is required to exploit the weakness, making it particularly concerning for enterprise environments where privileged access is maintained.
The technical mechanism behind this vulnerability stems from insufficient validation and resource management during the machine account creation process within Active Directory. When authenticated users submit requests to create numerous machine accounts, the system fails to properly throttle or limit the rate of account creation, leading to resource exhaustion that manifests as service hangs and system unresponsiveness. This behavior aligns with CWE-400, which categorizes resource exhaustion vulnerabilities as those that allow attackers to consume system resources beyond normal operational limits. The flaw essentially creates a scenario where the directory service becomes overwhelmed by legitimate authentication requests that are designed to be abusive in nature, causing the service to become unresponsive to other legitimate operations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire enterprise directory services infrastructure. Organizations relying on Active Directory for authentication, authorization, and identity management face significant risks when this vulnerability is exploited, as it can render critical services unavailable to legitimate users and systems. The service hang condition affects not only the immediate directory service but can also cascade to dependent systems that rely on Active Directory for user authentication and access control. This vulnerability particularly impacts environments where machine accounts are frequently created as part of standard operations, making the attack surface larger and more difficult to predict and defend against. The attack pattern aligns with ATT&CK technique T1499.004, which covers "Network Denial of Service" and specifically addresses service availability attacks that target directory services.
Mitigation strategies for CVE-2016-3226 should focus on implementing proper account creation controls and monitoring mechanisms within Active Directory environments. Organizations should establish limits on machine account creation rates and implement automated monitoring to detect unusual patterns of account provisioning. The implementation of proper access controls and least privilege principles can help reduce the attack surface by limiting which authenticated users can create machine accounts. Microsoft released patches and updates to address this vulnerability, and organizations should ensure all affected systems are properly updated. Additionally, implementing network segmentation and monitoring solutions can help detect and respond to exploitation attempts before they cause significant service disruption. Security teams should also consider implementing account lifecycle management policies that automatically review and remove unused machine accounts to minimize potential attack vectors.