bingbing - 9:56 am on Sep 28, 2012 (gmt 0)

"it doesn't really matter how the url was discovered"

Not even if it was malware or a malicious act. That would matter to us.

"accidentally stumble"

As has been stated, Bing does not guess URLs so no "accidental stumbling" has occured either. Other posters above concur with this.

Microsoft are investigating and say they are "concerned". We know it is not an issue our end as all files have been scanned and these URLs do not exist anywhere publically (and they are not in Bing/Google index either).

There was no 200 OK response. They got 404 in fact, according to the server logs.

"security through obscurity"

The folder had a IP restriction, but not a 401/3, so there is no security breach. We just want to know how it finds the addresses in the first place.

No one's whining here Phranque =;)