> On Thursday 30 Oct 2003 5:11 pm, Yannick Warnier wrote:
> > Le jeu 30/10/2003 � 17:56, Gary Stainburn a �crit :
> > > You can write $0 as well as reading it, which will change what appears
> > > when you run ps etc.
> > >
> > > This can be usefull for security reasons such as hiding sensitive data
> > > passed on the command line, and also for returning status
information for
> > > daemons.
> >
> > How? Could you explain that for me?
> >
> > Thanks,
> > Yannick
>
> security
>
> if you have the script:
>
> mylogon -u username -p password
>
> and someone (doesn't have to be root) runs
>
> ps ax
>
> they will see the command line that started the process, including your
> username and password.
>
> by having the command
>
> $0='mylogon -u xxxx -p xxxx';
>
> near the top of your script the data is hidden from prying eyes.
>
This should *NOT* be used for security purposes. It is very instance and
system dependent, from perldoc perlvar:
$0 Contains the name of the program being executed. On some oper-
ating systems assigning to $0 modifies the argument area that
the ps program sees. This is more useful as a way of indicat-
ing the current program state than it is for hiding the program
you�re running. (Mnemonic: same as sh and ksh.)
Note for BSD users: setting $0 does not completely remove
"perl" from the ps(1) output. For example, setting $0 to "foo-
bar" will result in "perl: foobar (perl)". This is an operat-
ing system feature.
Security through obscurity bad.....
http://danconia.org
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