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
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