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Re: [Full-disclosure] SSH brute force blocking tool

From: J. Oquendo (silinfiltrated.net)
Date: Mon Nov 27 2006 - 15:41:43 CST

Tavis Ormandy wrote:
> On Mon, Nov 27, 2006 at 04:21:19PM -0500, gabriel rosenkoetter wrote:
>> Mea culpa. Tavis's exploit doesn't so scary things, although he's
>> right you should really be doing a bit more sanitization of (evil)
>> user-supplied input, given that you're (insisting that you) run as
>> root.
> Gabriel, I was referring to this line:
> awk '!/#/ && /\./ && !a[$0]++
> {print "iptables -A INPUT -s "$1" -i eth0 -d '$ifaddr' -p TCP --dport 22
> -j REJECT"}' /etc/hosts.deny |\
> awk '/iptables/ && !/#/ && !/-s -i/'|sh
> (note the |sh), $1 can be controlled by specially crafted attempted
> logins.
> Thanks, Tavis.

That specially crafted attempt would be a HUGE raping of TCP/IP. How do
you supposed it would be possible for someone to insert 0wn3ed or any
other variable outside of an IP address?

J. Oquendo
sil . infiltrated net http://www.infiltrated.net

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