full-disclosure - Idle scan rediscovered!!!

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Date: Fri May  5 18:33:13 2006
From: blancher at cartel-securite.fr (Cedric Blancher)
Subject: Idle scan rediscovered!!!

Le vendredi 05 mai 2006 ? 18:49 +0200, Cedric Blancher a ?crit :
> As standard 2.4/2.6 kernels behaviour is to set DF flag to 1, and IPID
> to 0, it's a very bad candidate for an idle host.

Mitigating this...

1. there's Marco Ivaldi finding posted on Bugtraq
2. There seem to be something with ACK packets to exploit for
   idle-scanning:

	hping3 -A -r host -p 80

Gives back exploitable incremental IPID on a Linux 2.6.15 box.

Note that default ip_conntrack_tcp_loose of 3 prevents theses packets to
get flaged as INVALID by conntrack.

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