Microsoft has issued an updated warning for a critical security vulnerability in Active Directory Domain Services, tracked as CVE-2025-21293.
This flaw could permit an attacker who has already gained initial access to a system to escalate their privileges, potentially gaining complete control over the affected domain controller and undermining the security of the network infrastructure.
The vulnerability is categorized as an “Elevation of Privilege” issue stemming from an improper access control weakness, formally identified as CWE-284.
According to Microsoft’s advisory, an attacker who successfully exploits this flaw could elevate their privileges to the SYSTEM level.
Gaining SYSTEM privileges is the highest level of access on a Windows system, allowing an attacker to perform any action without restriction.
This includes installing malicious software, modifying or deleting critical data, and creating new administrative accounts, which could be used to establish persistence within the network.
The vulnerability was initially reported on January 14, 2025, with Microsoft providing an update on September 9, 2025, to offer further clarity.
Exploit Conditions And Assessment
Microsoft has assessed the exploitability of this vulnerability as “Exploitation Less Likely.” A key factor in this assessment is the attack vector, which requires an attacker to first log on to the target system.
This means the flaw cannot be exploited remotely by an unauthenticated user. The adversary must possess valid credentials, which could be obtained through tactics like phishing, credential stuffing, or exploiting a separate vulnerability.
Once authenticated, the attacker would need to run a specially crafted application to trigger the flaw and escalate their privileges.
At the time of the latest update, the vulnerability had not been publicly disclosed, and there were no reports of it being actively exploited in the wild.
Despite the prerequisite of prior access, the severity of the potential impact makes patching a critical priority for IT administrators.
An attacker with SYSTEM-level control on a domain controller can compromise the entire Active Directory forest, putting all domain-joined resources at risk.
Organizations are strongly advised to apply the security updates released by Microsoft to protect their domain controllers from this threat.
This incident serves as a reminder that a defense-in-depth security strategy, which includes regular patching, network segmentation, and monitoring for anomalous user activity, is essential to defend against multi-stage attacks that leverage local privilege escalation vulnerabilities.
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The post Microsoft Warns of Active Directory Domain Services Vulnerability, Let Attackers Escalate Privileges appeared first on Cyber Security News.
