CVE-2020-1472

Se presenta una vulnerabilidad de elevación de privilegios cuando un atacante establece una conexión de canal seguro Netlogon vulnerable hacia un controlador de dominio, usando el Netlogon Remote Protocol (MS-NRPC), también se conoce como "Netlogon Elevation of Privilege Vulnerability".

A flaw was found in the Microsoft Windows Netlogon Remote Protocol (MS-NRPC), where it reuses a known, static, zero-value initialization vector (IV) in AES-CFB8 mode. This flaw allows an unauthenticated attacker to impersonate a domain-joined computer, including a domain controller, and possibly obtain domain administrator privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

An elevation of privilege vulnerability exists when an attacker establishes a vulnerable Netlogon secure channel connection to a domain controller, using the Netlogon Remote Protocol (MS-NRPC). An attacker who successfully exploited the vulnerability could run a specially crafted application on a device on the network. To exploit the vulnerability, an unauthenticated attacker would be required to use MS-NRPC to connect to a domain controller to obtain domain administrator access. Microsoft is addressing the vulnerability in a phased two-part rollout. These updates address the vulnerability by modifying how Netlogon handles the usage of Netlogon secure channels. For guidelines on how to manage the changes required for this vulnerability and more information on the phased rollout, see How to manage the changes in Netlogon secure channel connections associated with CVE-2020-1472 (updated September 28, 2020). When the second phase of Windows updates become available in Q1 2021, customers will be notified via a revision to this security vulnerability. If you wish to be notified when these updates are released, we recommend that you register for the security notifications mailer to be alerted of content changes to this advisory. See Microsoft Technical Security Notifications.

Tom Tervoort discovered that the Netlogon protocol implemented by Samba incorrectly handled the authentication scheme. A remote attacker could use this issue to forge an authentication token and steal the credentials of the domain admin. This update fixes the issue by changing the "server schannel" setting to default to "yes", instead of "auto", which will force a secure netlogon channel. This may result in compatibility issues with older devices. A future update may allow a finer-grained control over this setting. Various other issues were also addressed.

Microsoft's Netlogon Remote Protocol (MS-NRPC) contains a privilege escalation vulnerability when an attacker establishes a vulnerable Netlogon secure channel connection to a domain controller. An attacker who successfully exploits the vulnerability could run a specially crafted application on a device on the network. The vulnerability is also known under the moniker of Zerologon.