CVE-2021-42282 in Windows
Summary
by MITRE • 11/10/2021
Active Directory Domain Services Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 08/21/2026
This vulnerability represents a critical elevation of privilege flaw in Microsoft Active Directory Domain Services that allows attackers to escalate their privileges from a standard user account to domain administrator level. The vulnerability stems from improper validation of the SAM Account Name attribute during the authentication process, creating a pathway for malicious actors to exploit the system's trust mechanisms. Unlike other related vulnerabilities such as CVE-2021-42278 and CVE-2021-42287, this specific flaw operates through a distinct attack vector involving the manipulation of account names and service principal names within the directory service infrastructure.
The technical exploitation of CVE-2021-42282 occurs when an attacker can authenticate to a domain controller using a valid user account and then leverage the flawed validation logic to create or modify accounts with elevated privileges. The vulnerability specifically targets the way Active Directory processes the SAM Account Name field, allowing attackers to bypass normal authentication checks by manipulating the account name format. This flaw enables the creation of domain-level accounts with administrative privileges without requiring legitimate administrative credentials, fundamentally undermining the security model of the directory service. The issue manifests when the system fails to properly validate that the SAM Account Name attribute matches the expected format and constraints during authentication operations.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with a persistent backdoor into domain environments that can be leveraged for lateral movement and data exfiltration. Once exploited, the attacker gains the ability to modify domain objects, create new administrative accounts, and potentially compromise the entire Active Directory infrastructure. The vulnerability affects multiple Windows Server versions including Windows Server 2016, Windows Server 2019, and Windows Server 2022, making it particularly dangerous in enterprise environments where these systems are commonly deployed. Organizations with default Active Directory configurations are especially vulnerable, as the attack requires minimal privileges to execute successfully and can be automated using readily available exploitation tools.
Security professionals should implement immediate mitigations including the deployment of Microsoft's security patches, the enforcement of strong account naming conventions, and the implementation of additional authentication controls such as multi-factor authentication. The vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate system access. Organizations should also monitor for unusual account creation patterns and implement network segmentation to limit the potential impact of successful exploitation. The flaw demonstrates the importance of proper input validation and attribute checking in directory services, as outlined in CWE-20 which addresses improper input validation. Additional defensive measures include the implementation of privileged access management solutions, regular security assessments of Active Directory configurations, and the enforcement of least privilege principles across all domain accounts to minimize the potential damage from successful exploitation attempts.