Strange?inx=<URL> page requests

Any ideas?

[ofnimira]

I wrote a small PHP script for my webpages so that if?inx=1 was added to the end of the URL then it would show an index of the site on the page. Since I've done that I've been getting strange page requests of the form <My Page>?inx=<Another URL> . It looks like a bot, as it typically requests 10-20 pages, about a second apart, although it doesn't look at robots.txt. Of the 10 - 20 requests, there are always three of the form shown, with different URLs for the <Another URL> part. So what can it be?

Referrer Spam?- well its a bit indirect (the referrer is always blank).
Blog Spam? - (i.e. thinking that it will show the <Another URL> instead of my page, which it doesn't). Well I'm pretty sure that these don't come from links.

The IP addresses seem to be from all over the place, and the User agent is just Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; .NET CLR 1.1.4322)

Any ideas?

[wilderness]

There was a recent thread in the Apacher Server forum regarding the vulnerability of adding phrases into your link URL's and the ability of others to hijack the URL's as a result.

There's also a similar thread in the Google News forum.