Hi all. Yes, as the title states, here's another variable expansion plea. You see, a friend of mine has a hand-rolled template parser, and won't accept my advice to check CPAN and use one of the undoubtedly better tested versions.

So I figure I'm going to give him a list of examples of why his hand-rolled system is insecure. A little scare tactic to spread the word, if you will. (: I was wondering if you, as the perlmonks.org userbase, could give me a few examples of your own, as to why the following code is insecure - the more disturbing, the better: 

#!/usr/bin/perl

my ($template, $F_H,$file);

$file = "file.txt";
if( open $F_H, $file )
{
    local $/ = undef;
    $template = <$F_H>;
    close($F_H);
}

$template =~ s/\[(\$[\w\[\]\{\}\'\"]*)\]/$1/eeg;
print "Content-type: text/plain\n\n";
print $template;

[download]
file.txt is filled with 'variables' that look like [$this] - I've already found that i can call lots of perlvar ($0, $ENV{HOME}) from it, as well as such niceties as [${system'ls'}] etc. Please note that I'm disregarding the lack of use strict and -w, as I can only fight one battle at a time. ):

Can anyone find anything else insecure about it?

Thanks,

strfry()

In reply to Yet Another Variable Expansion Problem by strfry()

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