Recently I've been seeing a major uptick in the following type of requests to my Apache logs:

> 
> "GET /CHANGELOG.txt HTTP/1.1" 404 211
> 
> 
> 

About a month ago, I received none. Now I receive a dozen or so each day. Occasionally they are accompanied by other more obvious vulnerability scans, but usually they come by themselves.

They are all coming from IP addresses that would be *very* unusual for users of our server.

I'm not particularly worried about a direct security threat, because they are 404. 

However my question is:

* Is this actually a vulnerability scan? If so, which one?
* If it isn't, does anyone know what it is? Have others been having these recently too?