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TUCoPS :: Unix :: General :: hide.txt

Covering Up Actions in UNIX




                     UNIX  Abuse Collection
              Written By ZeeBee Australia Jan 1990


     Ok Hacksters...we all know the importance of a good 
understanding of the UNIX V operating system, but I find that 
just an understanding alone is quite simply not enough.

     Our little articles are not intended for those wishing to 
gain an understanding of the UNIX environment.  Instead, we aim 
to show you how to truly ABUSE the UNIX system to it's fullest 
potential.(And lets face it, UNIX really does have some really 
great abusable features!)..so....grab your UNIX accounts and 
passwords, and lets go!


                **UNIX ABUSE COLLECTION PART 01**
           ****INVISIBILITY AND COVER UP TECHNIQUES***

     One thing that really used to bug me about using a UNIX 
system was that I always felt like someone was watching me.  It's 
just too easy to see what other users are doing, and as soon as 
you discover something good, everyone else sees what you are 
doing, and VOOM!...there goes your big secret.  System operators 
too, can easily pinpoint just who is stuffing around with their 
system simply by seeing what processes are running under your 
name.  So, I set out to find ways around this.

     One way to cover up what you are doing is to find and copy 
the command that you wish to perform.  As an example, just say I 
want to cat a whole load of bullshit to someones terminal, but I 
dont want anyone to see that I am executing the cat command.  
First of all I find the cat command.  On most systems it will be 
somewhere in the /bin directory.  Once you have found the command 
you must copy it (if possible) to your own directory and rename 
it to something inconspicuous.  Most commands can be found 
somewhere in the /bin or /usr/bin directories, but if you cant 
find them, just look at your path list and see where UNIX is 
looking for them. (typing echo $PATH is one way to view your path 
list.)
     Keep it in mind that not all commands are copyable (do an ls 
-al and look at the access flags to see if they are) if the 
access flags have an 'r' in the column 3rd from the far right, 
then you can read it, ie copy it !
     One advantage to this technique is that if you find a bug 
with a certain command, you have a copy of the faulty code, so 
even if the computer staff fix the bug, you will have the old 
version !  Neat !

     BUT! Don't worry if you can't copy the file!  The following 
technique will do just the same job, without the need to copy the 
file.  To do this you will need to write a program in C, compile 
it, and place it somewhere where it is safe for you to call 
whenever you want.


This is the small, and usefull piece of code:

main()
{
     execl("/bin/ls","a.out","-l",(char *)0);
}
     

     The above piece of code will execute the ls -l command, but 
will generally show up as a.out -l whenever someone has a look at 
what you are doing!
     The "/bin/ls" is the path of the 'ls' command.  Put the path 
of any program you wish to execute here.
     The "a.out" is what anyone else will think you are running. 
Put anything you want here.  The command doesnt even have to 
exist!
     The "-l" is the flag being passed to the ls command.  You 
cant cover up flags which are passed.  Damn!


     So, by using this, you can run any program with execute 
access and make it look like you are running something else.  You 
could even put in a whole path where I put the "a.out" and 
really confuse the shit out of people when they go looking for 
this great program you are running.

     While we are on the topic, I would just like to stress the 
importance of continually checking to see what others on the 
system are doing.  I find the "w -d" "ps -fu USERNAME" and "ps -
fa" commands to be most usefull at this.  On one system I was 
actually able to see system operators creating new accounts, and 
the account names and passwords were being passed. So one of the 
processes being executed by some priveleged user looked like 
this:

megauser  273 10:00:12  createaccount john zephyr ;

* In the above example, john is the account name, zephyr is the 
password.*

We got about 100 accounts that day !

     And remember, as soon as any new toy is installed on the 
system, somebody will be using it, so just keep an eye on them to 
see what they do.



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