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Bugtraq: fpf module and packet fragmentation:local/remote DoS.

fpf module and packet fragmentation:local/remote DoS.

From: XR Agent <prp_sc_at_antionline.org>
Date: Sat, 2 Jun 2001 13:45:26 -0700
('binary' encoding is not supported, stored as-is) Fpf kernel module by |CyRaX| [cyrax_at_pkcrew.org] (www.pkcrew.org) alters linux tcp/ip stack to emulate other OS'es against nmap/queso fingerprints using parser by FuSyS that reads nmap-os-fingerprints
for os emulation choice.

However, attempts to send fragmented packets to local or remote machine with nmap (-sS -f, -sN -f, -sX -f, -sF -f, -sA -f) or hping (hping -f) using host with loaded fpf.o lead to kernel panic ("Aiee, killing interrupt handle. Kernel panic: Attempted to kill the idle task ! In interrupt handler - not syncing.") if run from console or force immediate reboot if the packet sending tool is run from an xterm. When fpf.o - running machine recieves nmap / hping fragmented packets from remote hosts system freezes.

Security through obscurity was never a pefect solution, but in the current case there is also a hefty price to pay: complete inability of tcp/ip stack of "obscured" machine to deal with packet fragmentation.

Tested on Slackware 7.1 kernel 2.2.16 (i386).

Regards,

      _clf3_ (PrP_Sc_at_antionline.org)
     
      Veneficio, ergo sum.

   

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Received on Jun 04 2001

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