Vulnerability in Windows Defender Application Control Let Hackers Bypass It’s Security Feature

Microsoft released a new security update for the vulnerability that affected Windows Defender Application Control (WDAC) that allows a local attacker to bypass the WDAC security feature.

Windows Defender Application Control restricts which applications users are allowed to run and the code that runs in the system core. WDAC also block unsigned scripts and MSIs, and Windows PowerShell runs in Constrained Language Mode.

According to Microsoft advisory, An attacker who successfully exploited this vulnerability could circumvent PowerShell Core Constrained Language Mode on the machine.

In order to exploit this vulnerability, the Attacker first gains administrator access to the local machine where PowerShell is running in Constrained Language mode which leads an attacker leverage script debugging to abuse signed modules and access resources in an unintended way.

The vulnerability affects PowerShell Core prior to the following versions:

PowerShell Core VersionFixed in
6.16.1.5
6.26.2.2

If you want to check whether the system is vulnerable follow the below instruction that suggested here,

  1. Run pwsh -v, then, check the version in the table in Affected Software to see if your version of PowerShell Core is affected.
  2. If you are running a version of PowerShell Core where the executable is not pwsh or pwsh.exe, then you are affected. This only existed for a preview version of 6.0.

If you find that your system running with an affected version, you can download the latest version here at PowerShell Core Releases page.

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