CVE-2023-21768 in Windows
Summary
by MITRE • 01/11/2023
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability.
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Analysis
by VulDB Data Team • 03/09/2023
The Windows Ancillary Function Driver for WinSock represents a critical elevation of privilege vulnerability identified as CVE-2023-21768 that affects multiple Windows operating systems including Windows 10, Windows 11, and various Windows Server versions. This vulnerability resides within the ancillary function driver component that manages socket operations and network communications, specifically impacting the way the system handles privilege escalation during socket function calls. The flaw allows an unauthenticated attacker to potentially execute arbitrary code with elevated privileges, effectively bypassing standard security controls that normally prevent unauthorized access to system resources.
The technical root cause of this vulnerability stems from improper input validation within the WinSock ancillary function driver implementation. When processing certain network requests or socket operations, the driver fails to properly validate the privileges associated with incoming requests, creating a condition where malicious input can manipulate the driver's behavior to elevate system privileges. This represents a classic privilege escalation flaw that aligns with CWE-264, which specifically addresses permissions, privileges, and access controls within software systems. The vulnerability manifests when the driver processes certain IOCTL (Input/Output Control) requests that should require administrative privileges but instead accept requests from lower-privileged accounts.
From an operational perspective, this vulnerability presents significant risk to enterprise environments where Windows systems are deployed. Attackers can exploit this flaw without requiring authentication, making it particularly dangerous in environments where network exposure is high or where systems may be compromised through other attack vectors. The attack surface extends to any system that utilizes WinSock functionality, including web servers, database servers, and desktop systems that handle network communications. The vulnerability's exploitation potential is enhanced by its ability to function across multiple Windows versions, increasing the overall attack surface and reducing the effectiveness of version-specific mitigations.
The impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation can lead to complete system compromise and persistent access. The attacker gains the ability to execute code with kernel-level privileges, potentially allowing for full system takeover, data exfiltration, and establishment of backdoors. This aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" and demonstrates how vulnerabilities in system drivers can be leveraged to achieve unauthorized access to critical system resources. Organizations running affected systems face potential data breaches, service disruptions, and compliance violations that could result in significant financial and reputational damage.
Organizations should implement immediate mitigations including applying the relevant Microsoft security updates, disabling unnecessary network services, and implementing network segmentation to limit exposure. Security monitoring should focus on unusual socket activity and privilege escalation attempts, while endpoint detection and response solutions should be configured to flag suspicious driver behavior. The vulnerability also highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that reduce the attack surface of Windows systems. Additionally, organizations should review their access control policies to ensure that only necessary network services are exposed to external networks, and consider implementing additional security controls such as application whitelisting to prevent exploitation of this and similar vulnerabilities.