keyplyr - 8:26 am on Jul 31, 2012 (gmt 0)
You'll see they all are Chrome browsers. I've been seeing them for about 6 months. Sometimes they are followed by other tell-tale signs that this is the Chrome security check. As I said above, there are also a couple other appendages that sometimes occur. Sorry I forget the others, but they are along the same lines: undefined, warning, safe, etc (those are not the exact terms, but you get the idea.)
I don't use Chrome very much as I have all my tools with Firefox. But along the same lines, I've seen the red warning page alerts when Firefox has a web page classified as a threat. When Chrome does this, I believe these "undefined" (and other appended terms) end up in the server logs when the user then clicks through that warning, gaining the added parameter (appended term.) This shouldn't happen, but it does sometimes.