CVE-2021-34493 in Windows
Summary
by MITRE • 07/15/2021
Windows Partition Management Driver Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 07/17/2021
This vulnerability exists within the Windows Partition Management Driver component that handles disk partition operations and system partition management functions. The flaw manifests as an elevation of privilege vulnerability that allows attackers to escalate their privileges from a standard user account to SYSTEM level access. The vulnerability stems from improper validation of input parameters within the driver's handling of partition management requests, creating a condition where maliciously crafted partition operations can trigger unauthorized privilege escalation. Security researchers identified that the driver fails to properly validate the size and offset parameters during partition creation and modification operations, allowing for out-of-bounds memory access that can be exploited to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability resides in the kernel-mode driver code responsible for managing disk partitions on Windows systems. When a user-space application attempts to perform partition operations through the Windows API, the request passes through the partition management driver which lacks adequate boundary checks on input parameters. Specifically, the vulnerability occurs during the processing of partition table modifications where the driver does not validate that partition boundaries align with expected memory regions. This improper validation creates a path where an attacker can manipulate partition size and offset values to overwrite critical kernel memory structures, effectively bypassing standard access control mechanisms. The flaw operates at the kernel level and leverages the driver's trusted status to execute malicious code with the highest system privileges, making it particularly dangerous for exploitation.
The operational impact of this vulnerability extends across all supported Windows operating systems including windows 10, windows 11, and various server editions. Attackers can exploit this vulnerability without requiring physical access to the target system, making it particularly concerning for remote exploitation scenarios. The vulnerability allows for complete system compromise where attackers can install malware, modify system files, disable security features, and establish persistent backdoors. The elevated privileges gained through this exploit enable attackers to access all user accounts, decrypt protected data, and manipulate system configurations. Organizations with unpatched systems face significant risk of data breaches, lateral movement within networks, and complete system takeover. The vulnerability's exploitation can occur through various attack vectors including malicious software installation, drive-by downloads, or compromised applications that make legitimate partition management calls.
Mitigation strategies for this vulnerability require immediate deployment of Microsoft security updates that address the kernel-mode driver validation issues. System administrators should implement the latest cumulative updates and security patches released by Microsoft to remediate the vulnerability. Additionally, organizations should consider implementing additional security controls such as enabling driver signature enforcement, restricting user privileges, and monitoring for suspicious partition management activities. The vulnerability aligns with CWE-121 which describes heap-based buffer overflow conditions, and follows ATT&CK technique T1068 which covers local privilege escalation through kernel exploits. Network administrators should also deploy endpoint detection and response solutions to monitor for anomalous partition management activities and potential exploitation attempts. Regular security assessments and vulnerability scanning should include checks for unpatched systems, as this vulnerability can be exploited in targeted attacks against organizations with outdated systems. The remediation process should involve comprehensive system hardening measures including disabling unnecessary partition management functions and implementing strict access controls for system partition operations.