I have a web app which emails me exceptions automatically. This morning there was an error relating to a url: /Catalog/LiveCatalog?id=ylwpfqzts

id is invalid (should be a guid) and caused an error parsing. Everything was handled correctly, and an error page is returned. But what was odd is that the user-agent reported itself as Googlebot and the IP is registered to Google.

The URL would never have been generated by my web app but doesn't look particularly malicious.


If your app is like a lot of CMS, it may return the index page even if the page being access does not exist. You should create a custom 404 page which Google should adhere to.

Some more info: http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=93641

  • Thanks for the link. The site currently returns a 500 status code (with a custom page). I'll look at changing it to a 404, but I don't want to cause pages to get unindexed if there was a genuine bug in the code rather than bad inputs. – Rob Walker Feb 7 '11 at 15:36

It possible it's simple a bug in GoogleBot (it does happen). Or it could be a URL that you previously used and just hasn't been dropped from Google's sitemap for your site, however doubtful if you say that was never a valid URL.

There is also a slim chance that is was someone testing for exploits in your site by fiddling with URLs. I say slim cause it's not hard to fake as GoogleBot slightly harder to fake Google IP though.

For the moment I would write it off as a GoogleBot glitch but keep an eye out for it happening again.

  • It has been happening once a day for the last several days, always between 3am and 4am EST and always with a different random string from the id. The site has fairly light traffic and I doubt it would attract the attention of anyone wanting to find an exploit. – Rob Walker Feb 7 '11 at 15:34

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