Zero-Day Advisory

Fortinet Discovers Microsoft Windows Network Connectivity Assistant Elevation of Privilege Vulnerability


Fortinet's FortiGuard Labs has discovered an elevation of privilege vulnerability in Microsoft Network Connectivity Assistant that allows adversaries to execute arbitrary code under system context.

The Network Connectivity Assistant (NCA) service provides DirectAccess connectivity status information as well as diagnostic support on the client. The NCA validates that DirectAccess is working end-to-end by attempting to reach internal resources defined by the administrator during the configuration of DirectAccess.

The vulnerability in the NCA service allows arbitrary program execution under system context. To exploit the vulnerability, an attacker would first have to log on to the system. Then the attacker could run a specially crafted application that could exploit the vulnerability and take control of the affected system.


FortiGuard Labs released the following FortiGate IPS signature which covers this specific vulnerability:

Released Sep 04, 2019

Users should apply the solution provided by Microsoft.


Fortinet reported the vulnerability to Microsoft on July 01, 2019.

Microsoft confirmed the vulnerability on July 22, 2019.

Microsoft released patch for the vulnerability on September 10, 2019.


This vulnerability was discovered by Wayne Low of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.