133 lines
4.9 KiB
Plaintext
133 lines
4.9 KiB
Plaintext
==Phrack Inc.==
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Volume One, Issue Six, Phile 5 of 13
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===============================================================================
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------------
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Unix Nasties
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------------
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By Shooting Shark
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Written on April 3, 1986
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===============================================================================
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Summary: Methods of sabotaging your favorite Unix system.
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Preface: I do not advocate utilizing ANY of the methods I put forth in this
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file. Unix is a cool operating system, perhaps one of the best
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systems ever designed in many respects. If you have access to a Unix
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system, you should LEARN UNIX AND LEARN C, because that is where the
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money is in the computer world. However, Unix is a relatively
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insecure operating system which is easy to fuck up. This file
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explains a few ways of doing so.
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Crash The System
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----------------
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Unix has no built-in provision for the maximum amount of disk space allowed per
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user. Thus, one user can grab all the disk space on the system and effectively
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prevent anyone else from writing to the disk. A simple way of grabbing all the
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disk space is to create subdirectory after subdirectory until it is no longer
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possible. Here are a few ways of doing it.
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1> Create a file with the following lines:
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mkdir subdir
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cd subdir
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source /u1/mydir/crash
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Call it crash. The last line ("source /u1/mydir/crash") should be altered
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so that it will look for the file in your directory. If your directory is
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/u3/students/jeff, the last line should say "source
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/u3/students/jeff/crash". After you write the above file, type:
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% source crash
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and wait...within a few minutes the program will abort because it won't
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have any more room on the disk. Neither will anyone else.
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2> Here's a more elegant way of doing the same thing. Create this "endless
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loop" shellscript:
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while : ; do
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mkdir subdir
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cd subdir
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done
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and then "source" the file. If you are in the "sh" shell (if you are, you
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will probably have a "$" prompt) you can type "while : ; do" from the $
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prompt. You will then get a > prompt. Type the next three lines and sit
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back.
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3> If you'd like to set the process in motion and hang up, and the file is
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called crash, type:
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% nohup source crash &
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and log off. This will start it as a background process, allowing you to
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log off. However, log off QUICKLY, since if you used the first example for
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your crash file, it will also eat up background processes like crazy which
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will also fuck up the system to some extent. Which brings us to...
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Slow Down The System Immensely
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------------------------------
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There are many ways of doing this, the method being creating a sufficiently
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large number of background processes. Here's one specific example. Create a
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file called "slow1" with the following lines:
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w &
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source slow1
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create a file called "slow2" with:
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source slow1 &
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source slow2
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and execute slow2 with
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% slow2
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or
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% slow2 &
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This will create 25 background processes, each one running 25 background
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processes. The system will hardly move after you've got each one running.
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Messing Up A Directory
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----------------------
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Many file-handling commands use "-" options. Create a file with a "-" at the
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beginning of its name by doing this:
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cat > -filename
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[now type a few lines, maybe something rude like "ha ha you can't delete this
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file".] Type a ^D (control-d) to end input. You now have a file called
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-filename in your directory. It will be VERY difficult to remove this file.
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If you were to try rm (remove) -filename or mv (rename) -filename, the rm or mv
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program would interpret -filename as an option, not a file, and would give you
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an error message telling you that -filename was not a valid option...thus, the
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file stays there obnoxiously.
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Create a couple of hundred files with "-" as the first characters in their
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names...it will be a royal pain for the person who is blessed with these new
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files, and they will probably just have to get a new login.
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Conclusion
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The use of any of these techniques is quite irresponsible, and if anyone did
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this to my Unix system, I'd be quite pissed. That is why I strongly recommend
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that you never use these tricks.
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So Long,
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Shooting Shark
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"Some people have a bad attitude, and I say, if they want to act tough, beat
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'em up!" - Blue Oyster Cult
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-------------------------------------------------------------------------------
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For more information on UNIX sabotage and cracking, see the following articles:
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Ritchie, Dennis M. [he wrote Unix] "On the Security of UNIX." Programmers
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Manual for UNIX System III Volume II. Supplementary Documents.
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Filipski, Alan and Hanko, James. "Making UNIX Secure." BYTE Magazine, April
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1986, pp 113-128.
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===============================================================================
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