Letsencrypt acme-challenge on wordpress or asp.net

I have been trying without success to generate security certificates for my company using Let's Encrypt. My company uses WordPress 3.9.7 for its main website and I am not allow to upgrade to a newer version since that is handled by a third party company. The website is running on top of Internet Information Services 7.5 on Windows Server 2008 R2. My question is: How can I make wordpress handle http://www.company.com/.well-known/acme-challenge/mftvrU2brecAXB76BsLEqW_SL_srdG3oqTQTzR5KHeA ? I have already created a new empty page and a new template that returns exactly what let's encrypt is expecting but wordpress keeps returning a 404 for that page. My guess is that the problem arise with the dot(.) at the beginning of the route (".well-known") but I don't know how to solve that on wordpress.

I am also able to use an asp.net mvc website and make IIS point to that website for a while. Not a good idea though since clients may not be able to reach our website for a few minutes, but still an option. Then the question is: How can I create a controller or a route with a dot(".") at the beginning of the name? Help will be really appreciated.

For ASP.Net MVC or Web Forms, with certain Routing configs, you'll end up treating this URL as something for the Routing Engine to hand off to the MVC/Forms Handler, not a static file return. The result will be a 404 or a 503. The solution is surprisingly very simple:

If you haven't already, place the Challenge file:

Create the necessary dirs - .well-known is tricky mostly because Microsoft is lazy, but you can either do it from cmdline or create the folder as .well-known. and Windows Explorer will notice the workaround and remove the trailing period for you.
Inside \.well-known\acme-challenge place the challenge file with the proper name and contents. You can go about this part any way you like; I happen to use Git Bash like echo "oo0acontents" > abcdefilename

Then make a Web.Config file in the acme-challenge dir with these contents:

<?xml version = "1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <staticContent>
            <clear />
            <mimeMap fileExtension = ".*" mimeType="text/json" />
        </staticContent>

        <handlers>
            <clear />
            <add name="StaticFile" path="*" verb="*" modules="StaticFileModule,DefaultDocumentModule" 
            resourceType="Either" requireAccess="Read" />  
        </handlers>
    </system.webServer>
</configuration>

Source: https://github.com/Lone-Coder/letsencrypt-win-simple/issues/37

Done. The file will start returning instead of 404/503 allowing the Challenge to complete - you can now Submit and get your domain validated.

Aside: The above code snippet sets the content-type to json, a historical requirement that is no longer relevant to letsencrypt. The current requirement is there is no requirement - you can send a content-type of pantsless/elephants and it'll still work.