Bugtraq mailing list archives

Re: CheckPoint FW1 BUG


From: Hugo.van.der.Kooij () CAIW NL (Hugo.van.der.Kooij () CAIW NL)
Date: Sat, 15 Jul 2000 00:44:45 +0200


On Fri, 14 Jul 2000, uh Clem wrote:

On Fri, 14 Jul 2000 Hugo.van.der.Kooij () caiw nl wrote:

The first thing to do is to strip the host the FW-1 software is to be
installed on. Securing the OS before even starting to install the firewall
is essential.

When the firewall itself is dependant upon service being active, this is
somewhat difficult. See below.

FW-1 does not depend on any of these services! So they shouldn't be left
alive. Lance Spitzner wrote an article on how you should harden the
system. (Basically removing all those services.)

See also: http://www.enteract.com/~lspitz/papers.html

After installation you should secure the FW-1 software from any access to
the machine you don't explicitly want. Always pay attention to the implied
rules which can be made visible and should be thoroughly checked.

One of the other things we observed was the extremely poor state of
permissions that Firewall-1's installation leaves things in. As far as I
could tell, there was no option to run the firewall services as an
alternate user besides SYSTEM. Some would argue this is necessary, but it
really isn't; NT provides well documented APIs for adding specific
priviledges to a given user's token. These kind of mistakes are generally
present in win32 software written by people who haven't bothered to learn
the platform.

The vision is that this machine is a dedicated firewall. So no services
should be running. I'm unfamiliar with NT internals but it needs to
intervene on a rather low level (between NIC and IP stack) and wether such
an installation would be feasible without running as administrators is
unknown to me.

However it is quite unclear why accessing a port would cause a firewall
process to 100%. But FW-1 v4.0 SP4 is NOT certified for NT 4.0 SP6a and it
is recommended you upgrade to FW-1 v4.0 SP6 asap.

Ports 1030-103x are where registered RPC services are listening, much like
32767-328xx on Solaris. The ports are assigned by the RPC mapper (port 135
on NT, port 111 on Solaris) in the order the RPC services are
started. What I think is happening here is that the firewall-1 service in
question is running as an RPC service (frightening, eh?) and only expects
local connections.

FW-1 does not use RPC itself at all. I've seen a couple of dozen of
installations of FW-1 on just about any platform (besides Linux at present
;-) an know it runs on very bare systems.

Hugo.

--
Hugo van der Kooij; Oranje Nassaustraat 16; 3155 VJ  Maasland
hvdkooij () caiw nl     http://home.kabelfoon.nl/~hvdkooij/
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