In order to prevent command windows from popping up during installation I am using the WIX built-in custom action CAQuietExec.

First I define the command line:

<CustomAction Id="A01" 
       Property="QtExecCmdLine" Value="&quot;MyExe.exe&quot; /password [PASSWORD]" />

NB: The PASSWORD property is defined as Hidden. This prevents the Windows installer from writing the property value to the log.

Then I call into the embedded WIX extension:

<CustomAction Id="A02" BinaryKey="WixCA" DllEntry="CAQuietExec" Execute="immediate" Return="ignore" />

This works fine.

However, when I go to the temp folder and open up the MSI log I see the following entry:

CAQuietExec: "C:\Program Files\MyExe.exe" /password INCLEARTEXT

I.e. the password is displayed in clear text and not hidden.

How do I prevent the CAQuietExec from logging the password in clear text?