Microsoft Netlogon Privilege Escalation Vulnerability

CheckOps priority index

7.6/10 Patch within 7 days

Severity5.5

Probability9.9

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 99.4% higher than 99.9% of CVEs

CVSS 3.1 5.5 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:

Exploited for 1,826 days 03 Nov 2021

CISA due date 03 May 2022 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)03 Nov 2021
Exploited in EUVD (ENISA)03 Nov 2021
Used by ransomwareyes
EPSS above 10 %99.4%
No account, over the networkno

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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.

Affected products

Windows Server 2012Windows Server 2019 (Server Core installation)Windows Server 2016Windows Server 2012 R2Windows Server 2012 (Server Core installation)Windows Server 2008 R2 Service Pack 1Windows Server version 20H2Windows Server 2019Windows Server 2008 R2 Service Pack 1 (Server Core installation)Windows Server version 2004Windows Server, version 1909 (Server Core installation)Windows Server, version 1903 (Server Core installation)Windows Server 2012 R2 (Server Core installation)Windows Server 2016 (Server Core installation)Netlogon

Affected versions

6.2.0 <publication
10.0.0 <publication
6.3.0 <publication
6.1.0 <publication
6.0.0 <publication

Weaknesses (CWE)

CWE-330

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

17 Aug 2020
Published
03 Nov 2021
Exploitation reported (ENISA)
03 Nov 2021
Added to the KEV catalog
03 May 2022
CISA remediation due date
26 Sept 2026
EPSS peak: 99.4%

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