[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <AANLkTikgAYb_MrIVP0-ZMXnOrzdlJXtuNAJTwxmdmu8G@mail.gmail.com>
Date: Tue, 25 May 2010 02:03:16 -0700
From: Paul Lesniewski <paul@...irrelmail.org>
To: Thijs Kinkhorst <thijs@...ian.org>
Cc: oss-security@...ts.openwall.com, security-2010@...irrelmail.org,
Max Olsterd <max.olsterd@...il.com>, security@...de.org
Subject: Re: [SquirrelMail-Security] CVE Request for Horde and
Squirrelmail
On Sun, May 23, 2010 at 5:39 AM, Thijs Kinkhorst <thijs@...ian.org> wrote:
> On sneon 22 Maaie 2010, Max Olsterd wrote:
>> But someone gave me an explanation, with a live hacking demo, and it was
>> awesome : this guy has been able to scan the LAN of an international ISP
>> whereas there was a firewall blocking incoming packets to the LAN (DMZ +
>> internal LAN) !!!
>>
>> How ?
>>
>> He had an account on the squirrelmail (ISP) and he has been able to create
>> an exploit for the advisory we are talking about here. Thanks to that, he
>> asked squirrelmail to scan some ranges of IP addresses that were private
>> (10.x.x.x) and unreachable from the outside of this ISP (NAT). Then he
>> found multiple interesting hosts with unpatched services, which gave him
>> an idea of how secure it was for real when you are inside. He also used
>> the DNS scanning attack that was described in the slides of HITB, by
>> bruteforcing names, and he found other IP addresses (but a firewall
>> blocked the scan so deep on the LAN).
>
> That this is possible is inherent in providing the ability to your users to
> configure any POP3 server they want to retreive email. The whole idea of the
> POP3 fetch mail plugin is to allow to connect to other servers. And hence if
> you want to provide this functionality there will always be the possibility
> that someone connects to a local machine, and there's no real solution to that
> given the premise.
But there *is* a solution to the fact that they can connect to *any*
port on a local machine using this method. There isn't really a good
reason not to simply restrict the port number to the standard POP3
port, which would then remove the possibility that someone can use
SquirrelMail to port-scan your internal network. The next release of
SquirrelMail will do just that, and provide administrators a
configuration option where they can add other allowable port numbers,
or open it back up to any and all port numbers if they so feel they
need to.
> It is a choice to not patch internal services but any
> adminsitrator has the responsibility to determine what 'internal' means and
> who will have access to this network.
>
> And note that still the only thing you, as an authenticated user, can do is
> connect to those ports within a POP3 context.
Indeed, however, a port scan is still more than some administrators want.
> The only new idea that this research adds, is that they've scripted the
> changing of the pop3 server info so they can increase the amount of
> hosts/ports to connect to in a given timeframe. But even if this wouldn't be
> scriptable, it would still be possible for the user to specify POP3 servers by
> hand (as that is the goal of the plugin) and hence any network setup that
> can't deal with this but does enable the plugin, is broken by design.
>
> It's only a matter of scaling that they add. Anything that is 'vulnerable'
> with this, is already vulnerable if this scripting wouldn't be possible.
I don't think the question is about whether or not the vulnerability
can be scripted. The issue is that there *is* a vulnerability at all
(albeit a very minor one). I have thus applied for a CVE recently and
can report back when I receive it.
--
Paul Lesniewski
SquirrelMail Team
Please support Open Source Software by donating to SquirrelMail!
http://squirrelmail.org/donate_paul_lesniewski.php
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
