[11063] in bugtraq
Re: Checkpoint FW-1 identification
daemon@ATHENA.MIT.EDU (Jochen Bauer)
Sat Jul 17 23:54:44 1999
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Message-Id: <19990717131720.A1850@luna.theo2.physik.uni-stuttgart.de>
Date: Sat, 17 Jul 1999 13:17:21 +0200
Reply-To: Jochen Bauer <jtb@THEO2.PHYSIK.UNI-STUTTGART.DE>
From: Jochen Bauer <jtb@THEO2.PHYSIK.UNI-STUTTGART.DE>
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To: BUGTRAQ@SECURITYFOCUS.COM
In-Reply-To: <19990716082652.63061.qmail@securityfocus.com>; from Tim Hirst on
Fri, Jul 16, 1999 at 08:26:52AM -0000
On Fri, Jul 16, 1999 at 08:26:52AM -0000, Tim Hirst wrote:
> Hi all,
>
> This is not a bug but is instead a common procedural error.
> If a remote attacker performs a port scan on a network and
> finds a machine with ports 256, 257, and 258 open then it is
> a sure bet that they are running a Checkpoint FW-1 firewall.
Such a kind of firewall identification method also exists for AltaVista
Firewall (at least for Firewall97). In the default configuration there
are "traps" listening on ports 26/tcp, 27/tcp, 28/tcp and 29/tcp.
/etc/services:
[...]
ftp 21/tcp
telnet 23/tcp
strafe1 26/tcp
strafe2 27/tcp
strafe3 28/tcp
strafe4 29/tcp
smtp 25/tcp
time 37/tcp
[...]
If one connects to one of these ports, they generate the event of a
"connection attempt on unused port". As these "traps" are started by
inetd when a connection attempt occurs
/etc/inetd.conf
[...]
strafe1 stream tcp nowait root /usr/dfws/etc/strafe strafe
strafe2 stream tcp nowait root /usr/dfws/etc/strafe strafe
strafe3 stream tcp nowait root /usr/dfws/etc/strafe strafe
strafe4 stream tcp nowait root /usr/dfws/etc/strafe strafe
[...]
one can do a stealth scan on those ports to identify AltaVista Firewalls
(you know what to try next, don't you?) without the firewall detecting
the scan.
Jochen Bauer
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