WebApp Sec mailing list archives

Re: Should or shouldn't block public ping to a website


From: Clement Dupuis <clement.dupuis () gmail com>
Date: Sun, 11 Sep 2011 23:39:56 +0100

Good day to all,

The problem is that people do not selectively allow ping types.  They
allow ICMP or they don`t.

A tool like LOKI could be used as a client server tool to leak data in
an out of your servers.

ICMP Timestaps queries could be used to find out how long a server has
been up and running which could indicate which critical path requiring
a reboot has been or has not been installed on the remote server.

Netmask queries can be done to further identify specific range of IP's
being used.

ICMP redirect could be used.

ICMP offers limited benefits, pingning a server only tell you the
stack is configured and working, it does not tell you anything about
the specific services on the device itself.   It host can respond to
pings but it does not mean the services running on top of it are
working properly.

Other than ICMP Type 3 error messages, there is little benefit in allowing ICMP.

Take care

Clement



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SecureNinja
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On Fri, Sep 9, 2011 at 11:46, Sandeep Cheema <51l3n7 () live in> wrote:

Why are you not allowing ICMP? Is the server itself exposed or behind a netscaler or some routing device? Even if 
it's not covered behind, you can allow ping. The only exploit with ping is the ping of death, which is obsolete now. 
Use a software IDS\IPS?

Regards, Sandeep

Sent from BlackBerry® on Airtel

-----Original Message-----
From: ShiYih Lye <shiyih.lye () my offgamers com>
Date: Mon, 5 Sep 2011 06:03:57
To: <webappsec () securityfocus com>; <pen-test () securityfocus com>
Subject: Should or shouldn't block public ping to a website

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



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