CVE-2016-0020 in Windows
Summary
by MITRE
Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, and Windows 7 SP1 mishandle DLL loading, which allows local users to gain privileges via a crafted application, aka "MAPI DLL Loading Elevation of Privilege Vulnerability."
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/03/2022
The vulnerability identified as CVE-2016-0020 represents a critical privilege escalation flaw in multiple Microsoft Windows operating systems including Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, and Windows 7 SP1. This issue stems from improper handling of dynamic link library (DLL) loading mechanisms within the Windows MAPI (Messaging Application Programming Interface) subsystem. The vulnerability specifically affects systems where the MAPI component is installed and actively used, creating a pathway for local attackers to elevate their privileges from standard user level to system level access. The flaw manifests when the system loads DLL files in an insecure manner that does not properly validate the source or integrity of loaded components, allowing malicious code to be executed with elevated privileges. This vulnerability operates under the broader category of DLL loading vulnerabilities, which are classified under CWE-74 and CWE-155 in the Common Weakness Enumeration catalog, specifically addressing issues related to improper handling of dynamic libraries and insecure library loading practices.
The technical exploitation of this vulnerability occurs through a crafted application that leverages the insecure DLL loading behavior within the MAPI subsystem. When a local user executes a specially crafted application, the system's DLL loading mechanism fails to properly validate the location or authenticity of required libraries, allowing an attacker to place a malicious DLL in a location where it will be loaded by the vulnerable MAPI process. This process typically involves placing the malicious DLL in a directory that is searched before the legitimate system directories, taking advantage of the Windows DLL search order mechanism. The vulnerability is particularly concerning because it allows a local user to escalate privileges without requiring remote access or complex attack vectors, making it a significant concern for system administrators and security professionals. The attack vector relies on the principle that applications should not be allowed to load DLLs from arbitrary locations, a fundamental security principle that is violated in this scenario.
The operational impact of CVE-2016-0020 is substantial as it provides local attackers with a straightforward method to achieve system-level privileges, which can lead to complete system compromise. Once an attacker successfully exploits this vulnerability, they can gain full control over the affected system, potentially allowing them to install malware, modify system files, access sensitive data, or establish persistent backdoors. The vulnerability affects enterprise environments where multiple users may have standard accounts but require elevated privileges to perform administrative tasks, creating a significant risk for organizations that do not maintain strict security controls. The impact extends beyond individual systems to potentially affect entire network infrastructures, especially when combined with other exploitation techniques or when the compromised system serves as a gateway to other network resources. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques, specifically targeting the T1068 (Local Port Forwarding) and T1548.002 (Abuse Elevation Control Mechanism) tactics, demonstrating how insecure DLL loading can be leveraged to bypass standard security controls and gain unauthorized access to system resources.
Mitigation strategies for CVE-2016-0020 should focus on both immediate patching and operational security measures. Microsoft released security updates that address this vulnerability through proper DLL loading mechanisms and enhanced validation of library sources. Organizations should prioritize applying the relevant security patches as soon as possible, particularly for systems that are not running the latest Windows versions or are running unsupported operating systems. Additionally, implementing security controls such as application whitelisting, enforcing strict DLL search order policies, and monitoring for suspicious DLL loading activities can help reduce the risk of exploitation. System administrators should also consider disabling unnecessary MAPI functionality where possible and ensuring that only trusted applications have access to potentially vulnerable components. The vulnerability serves as a reminder of the critical importance of secure coding practices and proper DLL loading mechanisms, emphasizing the need for developers to follow secure programming guidelines that prevent insecure library loading behaviors. Organizations should also implement regular vulnerability assessments and penetration testing to identify and remediate similar insecure practices within their systems and applications.