Windows Defender Application Control Security Feature Bypass Vulnerability

A security feature bypass vulnerability exists in Windows Defender Application Control (WDAC) which could allow an attacker to bypass WDAC enforcement. An attacker who successfully exploited this vulnerability could circumvent Windows PowerShell Constrained Language Mode on the machine.

To exploit the vulnerability, an attacker would first have to access the local machine, and then place PowerShell into Constrained Language mode. By doing that an attacker could leverage script debugging to abuse signed modules in an unintended way.

The update addresses the vulnerability by correcting how PowerShell functions in Constrained Language Mode.