Microsoft has received a small number of reports from customers and others about continued activity exploiting a vulnerability affecting the Netlogon protocol (CVE-2020-1472) which was previously addressed in security updates starting on August 11, 2020. If the original guidance is not applied, the vulnerability could allow an attacker to spoof a domain controller account that could be used to steal domain credentials and take over the domain.
Deploying the August 11, 2020 security update or later release to every domain controller is the most critical first step toward addressing this vulnerability. Once fully deployed, Active Directory domain controller and trust accounts will be protected alongside Windows domain-joined machine accounts. We strongly encourage anyone who has not applied the update to take this step now. Customers need to both apply the update and follow the original guidance as described in KB4557222 to ensure they are fully protected from this vulnerability. We have updated the FAQs in that original guidance from August to provide further clarity.
- UPDATE your Domain Controllers with an update released August 11, 2020 or later.
- FIND which devices are making vulnerable connections by monitoring event logs.
- ADDRESS non-compliant devices making vulnerable connections.
- ENABLE enforcement mode to address CVE-2020-1472 in your environment.
Organizations that deploy Microsoft Defender for Identity (previously Azure Advanced Threat Protection) or Microsoft 365 Defender (previously Microsoft Threat Protection) are able to detect adversaries as they try to exploit this specific vulnerability against their domain controllers.
Finally, we have emphasized our previous guidance to relevant government agencies. For example, we contacted the Cybersecurity and Infrastructure Security Agency (CISA) which has issued an additional alert to remind state and local agencies, including those involved in the U.S. elections, about applying steps necessary to address this vulnerability.
VP Engineering, MSRC