How to creatively kill your system...

enigma_0Z · 10-17-2006, 11:05 AM

Just like the title says, how to creatively kill your system... (assume root access)

And root devs are /dev/hda1 (/boot), /dev/hda2 (swap), /dev/hda3 (/)

I'll just post the one everyone knows...

** NOT CREATIVE **

Code:

rm -rf /

OK, now here's mine:

Code:

dd if=/dev/urandom of=/dev/hda bs=512 count=1

raska · 10-17-2006, 11:23 AM

Set It On Fire!!!!! LOL

Dragineez · 10-17-2006, 11:27 AM

Silly, yes - deleting all files from your hard drive will destroy the system. Not worth mentioning. Now:

Code:

:(){ :|:& };:

That's a bit more clever, and it won't destroy your computer in the process.

pwc101 · 10-17-2006, 11:34 AM

oh come on, that's not fair! is there an explanation?...

Dragineez · 10-17-2006, 12:07 PM

I found this posted by another user on this forum. It is a Fork Bomb which creates a function that calls itself infinitely, consuming all process slots on the computer and freezing it.

crazyjimbo · 10-17-2006, 12:49 PM

Code:

alias ls="echo bash: ls: command not found"

It won't kill your system, but will seriously annoy anyone else who tries to use it!

raska · 10-17-2006, 01:06 PM

Quote:

Originally Posted by crazyjimbo

Code:

alias ls="echo bash: ls: command not found"

It won't kill your system, but will seriously annoy anyone else who tries to use it!

But by just typing:

Code:

$ which ls
/usr/bin/ls
$ \ls
avoids aliases

it's easy to beat that one

crazyjimbo · 10-17-2006, 01:11 PM

I know it isn't bulletproof, but would your first thought really be that someone has messed with your aliases? Maybe it would, but it sure wasn't mine! This worked on me like a treat.

raska · 10-17-2006, 01:14 PM

Quote:

Originally Posted by crazyjimbo

...but would your first thought really be that someone has messed with your aliases?....

LOL you are right, likely I would think that /usr got umounted or corrupted somehow

frob23 · 10-17-2006, 02:28 PM

Code:

:(){ :|:& };:

Code:

fork() {
    fork | fork &
}

fork

This is a more concise example of the above fork. That line spawns two versions of the program each time around and both those form two more, etc.

For a fun way...

Code:

chmod -Rf 0000 /*

Makes every file on the system unreadable, unwritable, and unexecutable. And it's fun to try and add execute persmissions back when chmod can't be run.

I like this because everything still there... so tempting... but so completely ruined. Reinstall time because you'll never get the permissions right again.

b0uncer · 10-17-2006, 02:34 PM

How about a live-cd

taylor_venable · 10-17-2006, 02:55 PM

Quote:

Originally Posted by frob23

Code:

chmod -Rf 0000 /*

I could have sworn I've been in situations before where this wouldn't work because it removed execute permission from the toplevel directory first, then tried the children. But I can't get it to work now, so maybe I'm thinking of chown instead...

Anyway, this being irreparable hinges on making / non-exec, but that means all you'd have to do to fix it is use a live CD and mount this partition somewhere the parent directory has exec bit set. Right?

Freex · 10-17-2006, 03:02 PM

Quote:

I found this posted by another user on this forum. It is a Fork Bomb which creates a function that calls itself infinitely, consuming all process slots on the computer and freezing it.

I used to do this on windows xp with batch files ... try running a program if you're pagefile is over 2GB and your real memory is only 512MB

In *NIX, if i wish to log out quicky i just enter (as root) killall x
works all of the time

frob23 · 10-17-2006, 03:53 PM

Quote:

Originally Posted by taylor_venable

I could have sworn I've been in situations before where this wouldn't work because it removed execute permission from the toplevel directory first, then tried the children. But I can't get it to work now, so maybe I'm thinking of chown instead...

Anyway, this being irreparable hinges on making / non-exec, but that means all you'd have to do to fix it is use a live CD and mount this partition somewhere the parent directory has exec bit set. Right?

Not quite. This command changes all the permissions of all the files and directories on the system. The part which makes it impossible to repair (at least without a reboot to clean media like a live CD) is that the tools you need to fix this (chmod in this case) can't be run because they don't have execute permission.

Yeah, it's also true that you can't navigate the filesystem thanks to the removal of the read and execute bits from directories (which makes it more frustrating).

Fixing this is more complicated than just mounting it somewhere else. You need to boot into a clean filesystem, like from a live CD, and repair all the permissions back to what they should be. It's probably easier to reinstall the base system and then go through and redo the user partitions by hand with a default umask of 0700 for directories and 0600 for files... and then let them make it less restrictive as they want.

There is nothing to prevent this command from running to completion because it's already in memory and running when it changes it's own permissions on disk.

Examples after running it:

Code:

# ls
ls: permission denied
# echo *
altroot bin boot dev etc home kern lib libexec mnt netbsd proc rescue root sbin stand tmp usr var
# cd bin
# echo *
[contents cut for space but shows all files]
#chmod +x /bin/ls
chmod: permission denied

All the files are still there but you can't use them or any of the utilities. Echo is a shell-builtin as is cd... so they still function although I'm shocked that you can cd still, that may be a function of how netbsd treats root though. Yeah, this is a netbsd system but the effect is the same everywhere.

St.Jimmy · 10-17-2006, 04:33 PM

how about a cron that greped *.* every minute and displayed the output? that would tick me off REAL bad