Get raw value of property attribute using Reflection

I need to mark some properties as passwords so that they could be automatically screened. I found a standard attribute for that:

[PasswordPropertyText]
public string ThePassword { get; set; }

Following method checks if the attribute is there:

private static bool _isPassword(PropertyInfo p)
{
    PasswordPropertyTextAttribute passProp = (PasswordPropertyTextAttribute)p.GetCustomAttribute(typeof(PasswordPropertyTextAttribute));
    return (passProp != null); // Additional condition should go here
}

Now I would like to have my own logic here:

• [PasswordPropertyText] should result in true.
• [PasswordPropertyText(true)] should result in true.
• [PasswordPropertyText(false)] should result in false.

but the default value of PasswordPropertyTextAttribute.Password is false when the argument is omitted.

Is there any way to get the raw attribute value?