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Date: Tue, 11 Dec 2012 22:42:11 +0000 (GMT)
From: Hurgel Bumpf <>
To: "" <>, Mario Vilas <>
Cc: "" <>
Subject: Re: Google's robot.txt handling

Hi guys,

thank you for your valuable feedback.

The question was raised, what prevents somebody to build a script to scan for the robots.txt manually. Seriously, let's call it just common sense. The time and effort invested does not pay off very well. 

This is why google is very useful in that way. Thousands of servers indexing the files in no time for free. 


Coman the Intensivecarian

 Von: Jeffrey Walton <>
An: Mario Vilas <> 
Gesendet: 22:38 Dienstag, 11.Dezember 2012
Betreff: Re: [Full-disclosure] Google's robot.txt handling
On Tue, Dec 11, 2012 at 4:11 PM, Mario Vilas <> wrote:
> I think we can all agree this is not a vulnerability. Still, I have yet to
> see an argument saying why what the OP is proposing is a bad idea. It may be
> a good idea to stop indexing robots.txt to mitigate the faults of lazy or
> incompetent admins (Google already does this for many specific search
> queries) and there's not much point in indexing the robots.txt file for
> legitimate uses anyway.
I kind of agree here. The information is valuable for the
reconnaissance phase of an attack, buts its not a vulnerability per
se. But what is to stop the attacker from fetching it himself/herself
since its at a known location for all sites? In this case, Google
would be removing aggregated search results (which means the attacker
would have to compile it himself/herself).

Google removed other interesting searches, such as social security
numbers and credit card numbers (or does not provide them to the
general public).


> On Tue, Dec 11, 2012 at 2:01 PM, Scott Ferguson
> <> wrote:
>> > If I understand the OP correctly, he is not stating that listing
>> > something
>> > in robots.txt would make it inaccessible, but rather that Google indexes
>> > the robots.txt files themselves,
>> <snipped>
>> Well, um, yeah - I got that.
>> So you are what, proposing that moving an open door back a few
>> centimetres solves the (non) problem?
>> Take your proposal to it's logical extension and stop all search engines
>> (especially the ones that don't respect robots.txt) from indexing
>> robots.txt. Now what do you do about Nutch or even some perl script that
>> anyone can whip up in 2 minutes?
>> Security through obscurity is fine when couple with actual security -
>> but relying on it alone is just daft.
>> Expecting to world to change so bad habits have no consequence is
>> dangerously naive.
>> I suspect you're looking to hard at finding fault with Google - who are
>> complying with the robots.txt. Read the spec. - it's about not following
>> the listed directories, not about not listing the robots.txt.  Next
>> you'll want laws against bad weather and furniture with sharp corners.
>> Don't put things you don't want seen to see in places that can be seen.
>> >
>> >
>> > On Mon, Dec 10, 2012 at 8:19 PM, Scott Ferguson <
>> > () gmail com> wrote:
>> >
>> >
>> >     /From/: Hurgel Bumpf <l0rd_lunatic () yahoo com>
>> >     /Date/: Mon, 10 Dec 2012 19:25:39 +0000 (GMT)
>> >
>> > ------------------------------------------------------------------------
>> >     Hi list,
>> >
>> >
>> >     i tried to contact google, but as they didn't answer my email,  i do
>> >
>> > forward this to FD.
>> >
>> >     This "security" feature is not cleary a google vulnerability, but
>> >
>> > exposes websites informations that are not really
>> >
>> >     intended to be public.
>> >
>> >     Conan the bavarian
>> >
>> > Your point eludes me - Google is indexing something which is publicly
>> > available. eg.:- curl http://somesite.tld/robots.txt
>> > So it seems the solution to the "question" your raise is, um,
>> > nonsensical.
>> >
>> > If you don't want something exposed on your web server *don't publish
>> > references to it*.
>> >
>> > The solution, which should be blindingly obvious,  is don't create the
>> > problem in the first place. Password sensitive directories (htpasswd) -
>> > then they don't have to be excluded from search engines (because listing
>> > the inaccessible in robots.txt is redundant).  You must of missed the
>> > first day of web school.

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