Web Application Security
Re: Should or shouldn't block public ping to a website Sep 07 2011 06:15AM
ShiYih Lye (shiyih lye my offgamers com) (2 replies)
hi,

What Todd said is pretty true, and that is what playing in my mind,
"what does blocking ICMP ping from public will buy me ?"

I have some other suggest me to use TCP traceroute to solve the issue
of not being able to get the traceroute result from my user during
troubleshooting. But the problem is, those website user just ordinary
shopper and they are almost all using Windows machine. Windows default
tracert is not able to do TCP traceroute, I believe. My site is
getting more weird routing issue from user around the world recently,
so I really need to know what part of my user's route is blocking us.
I can't ask a normal shopper to install network tools to help
troubleshoot the issue when what they want is a 5 minutes to settle
their needs. They will just go to other sites.

I think there is not much benefit of dropping ICMP from the public
compare with the bones it gives, at least for a ebusiness website,
doesn't it ? Anyone having different view is most welcome to chip in
your thought :)

Regards,
Lye

On Tue, Sep 6, 2011 at 11:35 PM, Todd Haverkos <infosec (at) haverkos (dot) com [email concealed]> wrote:
>
> ShiYih Lye <shiyih.lye (at) my.offgamers (dot) com [email concealed]> writes:
> > Hi,
> >
> > All this while I'm not allowing any public ping to the website I'm
> > maintaining, but it's making me tougher to troubleshoot should any
> > user from the globe having trouble to access our website, as I can't
> > make them to send a proper traceroute report.
> >
> > To your opinion, is it necessary to block public ping to a public
> > website ? Is this security practice still relevant in today exploit
> > technology ?
> >
> > And if you think it's still necessary, how do I make sure my user's
> > traceroute still work when all ICMP is dropped from public ?
> >
> > Thanks for any input, appreciated that.
> >
> > Regards,
> > Lye
>
> I agree with you--it's more headache than it's worth if supporting a
> public site with lots of users. Your site certainly isn't trying to
> hide, and attackers don't even need to actively scan to find it
> (i.e. search indexes surely know about it), you're in public dns
> likely at www.youdomain.com, vuln scanner's notion of "host aliveness"
> checks includes trying tcp connections to port 80 and many others.
> You might miss the crosshairs of _some_ script kiddies by not
> responding to ping, but really, what will that buy you?  Probably next
> to nothing.
>
> On the down side, telling people to "try to telnet to port 80" as a
> test of connectivity gets old quickly, and the issue you mention of
> traceroute is another good reason to forgo this anachronism.
>
> Of course as soon as we all agree on this, some obtuse overflow on
> maliciously formed ICMP packets will be discovered next week where
> denying ICMP will have saved us.   Ah, the risk management fun of
> balancing known and unknown unknowns. :-)
>
> Best Regards,
> --
> Todd Haverkos, LPT MsCompE
> http://haverkos.com/

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[ reply ]
Re: Should or shouldn't block public ping to a website Sep 09 2011 10:47PM
John Hall (j hall f5 com)
Re: Should or shouldn't block public ping to a website Sep 09 2011 01:12PM
Andre Correa (andre correa pobox com)


 

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