CVE-2021-1689 in Windows
Summary
by MITRE • 01/13/2021
Windows Multipoint Management Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/09/2024
This vulnerability resides within the Windows Multipoint Management functionality, specifically affecting the Windows Multipoint Server 2016 and Windows Server 2019 operating systems. The flaw represents a critical 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 multipoint management service implementation, creating a pathway for malicious code execution with elevated privileges.
The technical exploitation of CVE-2021-1689 occurs through a flaw in the Windows Multipoint Management service where insufficient input sanitization permits attackers to manipulate service parameters and gain unauthorized access to system resources. This vulnerability is classified under CWE-20 as "Improper Input Validation" and specifically relates to CWE-787 "Out-of-bounds Write" when the service processes malformed input data. The flaw manifests when the multipoint management service fails to properly validate the length and content of incoming parameters, allowing attackers to craft malicious payloads that trigger buffer overflow conditions or privilege escalation sequences.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary code with SYSTEM privileges, potentially leading to complete system compromise. Attackers can leverage this vulnerability to install persistent backdoors, modify system files, access sensitive data repositories, and establish footholds for further lateral movement within network environments. The vulnerability affects organizations running Windows Multipoint Server 2016 and Windows Server 2019, particularly those with multiple user accounts or remote access capabilities that utilize the multipoint management services. This makes it especially dangerous in enterprise environments where the service may be exposed to untrusted network segments or where administrative accounts have elevated privileges.
Security professionals should implement immediate mitigations including applying Microsoft security patches released in the May 2021 Patch Tuesday updates, disabling unnecessary multipoint management services, and implementing network segmentation to limit access to affected systems. The vulnerability aligns with ATT&CK technique T1068 "Exploitation for Privilege Escalation" and may also map to T1059 "Command and Scripting Interpreter" when attackers execute malicious code post-exploitation. Organizations should conduct comprehensive vulnerability assessments to identify systems running affected multipoint management services and implement monitoring for suspicious privilege escalation activities. The remediation process requires careful consideration of service dependencies and potential impact on legitimate business operations, as disabling the multipoint management service may affect authorized user access to shared computing resources.