Yes, -s is very bad, but I hadn't realized just how bad until you posted this.... Among the many globals that I could tweak with -s were $< $> $) and $( which should raise a huge security flag for anyone whos read perlvar. For instance, when saved as evildashs.pl, and envoked as:

% ./evildashs.pl -\<=0 -\>=0 -\(=0 -\)=0

The following code might raise some eyebrows.... 

#! /usr/bin/perl -wsT
use strict;

print "\$) = ", $), "\n";
print "\$( = ", $(, "\n";
print "\$< = ", $<, "\n";
print "\$> = ", $>, "\n";

__END__

=head1 OUTPUT
$) = 0
$( = 0
$< = 0
$> = 0

[download]
I don't think this actually gives the process any new powers, but it would allow someone to execute code that was only supposed to be invoked as root.

Oh, right. I should include the obligatory link to Getopt::Std and Getopt::Long for a much better way to handle command line options.

-Blake

In reply to Re: perl -s is evil? by blakem
in thread perl -s is evil? by malloc

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