CVE-2021-1698 in Windows
Summary
by MITRE • 02/26/2021
Windows Win32k Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-1732.
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Analysis
by VulDB Data Team • 02/26/2021
This vulnerability represents a critical elevation of privilege flaw within the Windows Win32k subsystem that allows attackers to escalate their privileges from standard user level to system level execution. The vulnerability resides in the kernel-mode component responsible for handling graphical user interface operations and window management functions. Attackers can exploit this weakness by crafting malicious input or manipulating specific windowing system calls that traverse the user-mode to kernel-mode boundary. The flaw specifically impacts the validation mechanisms within Win32k's handling of certain graphics-related structures, potentially allowing arbitrary code execution with elevated privileges.
The technical implementation of this vulnerability involves improper validation of user-supplied data during window management operations. When legitimate applications interact with the graphical subsystem through Win32k APIs, malicious input can cause the kernel to process unvalidated data structures that lead to privilege escalation. This type of flaw falls under CWE-121 which describes stack-based buffer overflow conditions, though the specific implementation may involve more complex memory corruption patterns. The vulnerability demonstrates a classic kernel-mode privilege escalation vector where user-level code can manipulate kernel data structures through improper input validation.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with complete system control and access to all resources available to the Windows kernel. Successful exploitation enables adversaries to install malware, modify system files, access sensitive user data, and establish persistent backdoors within the target environment. This makes the vulnerability particularly dangerous in enterprise environments where a single compromised account could lead to complete network compromise. The vulnerability's impact aligns with ATT&CK technique T1068 which describes local privilege escalation through kernel exploits, and T1547 which covers registry run keys and startup folder modifications that attackers often employ after gaining elevated privileges.
Mitigation strategies should focus on immediate patch deployment from Microsoft as the primary defense mechanism against this vulnerability. Organizations should implement comprehensive monitoring for unusual system calls or kernel-mode activity that may indicate exploitation attempts. Network segmentation and privilege separation practices can limit the potential impact even if exploitation occurs. Additionally, disabling unnecessary graphical services and implementing application whitelisting policies can reduce attack surface exposure. Security teams should also deploy endpoint detection and response solutions capable of identifying anomalous behavior patterns associated with kernel-mode manipulation. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and highlights the risks associated with complex kernel-mode subsystems that handle privileged operations. Regular security assessments and vulnerability scanning should include checks for unpatched Win32k components to prevent exploitation attempts.