CVE-2021-1648 in Windows
Summary
by MITRE • 01/13/2021
Microsoft splwow64 Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/09/2024
The Microsoft splwow64 elevation of privilege vulnerability represents a critical security flaw in the Windows operating system that allows attackers to escalate their privileges from a standard user account to system-level access. This vulnerability specifically affects the spooler service component known as splwow64.exe which is responsible for handling print jobs and printer management functions within Windows environments. The flaw resides in how the spooler service processes certain print job parameters and handles privilege checks during the print queue management operations. According to Microsoft security advisories, this vulnerability enables local attackers with standard user privileges to execute malicious code with elevated system privileges, effectively bypassing standard security controls that normally prevent privilege escalation.
The technical exploitation of CVE-2021-1648 occurs through manipulation of the Windows print spooler service functionality where attackers can craft specially crafted print jobs that trigger improper privilege validation within the splwow64.exe process. This vulnerability falls under the Common Weakness Enumeration category of privilege escalation flaws, specifically classified as CWE-269 which addresses improper privileges for critical resources. The attack vector typically involves a user executing a malicious print job or printer configuration that causes the spooler service to execute code with elevated privileges. The vulnerability is particularly concerning because it can be exploited locally on a system without requiring network access or additional authentication mechanisms, making it an attractive target for attackers who have already gained initial access to a compromised system.
From an operational impact perspective, this vulnerability creates significant risk for enterprise environments where multiple users share systems or where attackers have already established a foothold through other attack vectors. The ability to escalate privileges without requiring additional authentication means that attackers who gain access to a standard user account can immediately elevate their privileges to system level, providing them with complete control over the affected system. This includes access to all system files, registry settings, user accounts, and the ability to install malicious software or establish persistent backdoors. The vulnerability affects various Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern across enterprise networks. Organizations with multiple users or systems running vulnerable versions of Windows face heightened risk of complete system compromise.
Security mitigations for CVE-2021-1648 should include immediate deployment of Microsoft security patches that address the privilege escalation flaw in the spooler service. System administrators should also implement the principle of least privilege by disabling unnecessary printer services and restricting user permissions for print management functions. The Windows Defender Application Control feature can be configured to restrict execution of unauthorized print-related processes, while monitoring solutions should be deployed to detect unusual print job patterns that might indicate exploitation attempts. According to MITRE ATT&CK framework, this vulnerability maps to the privilege escalation technique T1068 which involves using vulnerabilities in operating systems or applications to gain elevated privileges. Organizations should also consider implementing network segmentation to limit lateral movement capabilities and deploy endpoint detection and response solutions that can identify suspicious behavior patterns associated with print spooler exploitation attempts. Regular security assessments and vulnerability scanning should include verification of spooler service configurations to ensure that the vulnerable splwow64.exe process is not unnecessarily exposed to untrusted users.