CVE-2020-1396 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists when Windows improperly handles calls to Advanced Local Procedure Call (ALPC).An attacker who successfully exploited this vulnerability could run arbitrary code in the security context of the local system, aka 'Windows ALPC Elevation of Privilege Vulnerability'.
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Analysis
by VulDB Data Team • 10/30/2020
The Windows ALPC elevation of privilege vulnerability represents a critical security flaw that enables attackers to escalate their privileges from standard user level to system level access. This vulnerability specifically targets the Advanced Local Procedure Call implementation within the Windows operating system, which serves as a high-performance inter-process communication mechanism used extensively throughout the Windows kernel and user applications. The flaw arises from improper handling of ALPC calls, creating an exploitable condition that allows malicious code execution with elevated privileges. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-264, which describes permissions, privileges, and access controls issues. The ATT&CK framework categorizes this as privilege escalation through system services, specifically targeting the Windows kernel's inter-process communication mechanisms.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious ALPC messages that trigger improper validation within the Windows kernel. The flaw allows an attacker to manipulate the security context of ALPC calls, effectively bypassing normal access controls that should prevent unauthorized privilege escalation. This typically involves exploiting memory corruption issues or improper input validation within the ALPC subsystem, enabling code execution in kernel mode with system-level privileges. The vulnerability is particularly dangerous because ALPC is fundamental to Windows system operations, used by numerous system components including the Windows Management Instrumentation, Windows Defender, and various Windows services. Attackers can leverage this weakness to gain complete system control, potentially leading to data exfiltration, persistent backdoors, or further network infiltration.
The operational impact of this vulnerability extends beyond immediate privilege escalation, as it provides attackers with a persistent foothold in targeted systems. Once exploited, attackers can maintain system-level access without requiring additional authentication or exploitation vectors. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern for enterprise environments. Security researchers have noted that this vulnerability is particularly challenging to detect because the exploitation occurs at the kernel level, making traditional endpoint protection solutions less effective. The exploitability factor is considered moderate to high, as it requires local access to the system but can be leveraged by attackers who have already gained initial access through other means such as phishing or web-based attacks.
Organizations should implement multiple layers of defense to mitigate this vulnerability, beginning with immediate patch deployment from Microsoft Security Updates. The vulnerability requires a system restart to fully remediate, making it critical for administrators to plan and execute patching schedules carefully. Network segmentation and privilege minimization practices should be enforced to limit the potential impact if exploitation occurs. Security monitoring should include detection of unusual ALPC activity patterns and anomalous system calls that might indicate exploitation attempts. The National Institute of Standards and Technology recommends implementing the principle of least privilege and maintaining up-to-date security baselines. Additionally, organizations should consider implementing application whitelisting policies and monitoring for suspicious kernel-mode activity, as these measures can provide additional protection against exploitation attempts. Regular security assessments and vulnerability scanning should include checks for unpatched systems running affected Windows versions to ensure comprehensive coverage of this critical vulnerability.