Abuse CPANM by hacking its library loading process to allow injecting arbitrary code.

winrar.pl

#!/usr/bin/env perl
# FILENAME: unfatten.pl
# CREATED: 01/24/15 04:55:06 by Kent Fredric (kentnl) <kentfredric@gmail.com>
# ABSTRACT: Attempt to extract files from a codes fatpacked library.

use strict;
use 5.010001;
use warnings;

{

    package Capture;
    use Tie::Array;
    our @ISA = ('Tie::Array');

    sub TIEARRAY {
        my ( $classname, %args ) = @_;
        return bless {
            original => $args{original},
            storage  => $args{storage},
        }, $classname;
    }

    sub FETCH {
        my ( $self, $index ) = @_;
        return $self->{original}->[$index];
    }

    sub FETCHSIZE {
        my ($self) = @_;
        return scalar @{ $self->{original} };
    }

    sub UNSHIFT {
        my ( $self, @list ) = @_;
        push @{ $self->{storage} }, $_ for @list;
        die "Capture done";
    }
}

my $storage = [];

sub capture {
    my $original = [@INC];
    {
        local @INC;
        tie @INC, 'Capture', ( storage => $storage, original => $original );
        local $@;
        eval { require "/home/kent/perl5/perlbrew/bin/cpanm"; };
    }
    untie @INC;
    @INC = @{$original};
}
use Scalar::Util qw(blessed);
capture();
for my $elem ( @{$storage} ) {
    next unless ref $elem;
    next unless blessed $elem;
    my $class = blessed $elem;
    my $orig  = $class->can('INC');
    my $new   = sub {
        return unless $_[1] =~ qr{\AApp/cpanminus};
        print "Fetching $_[1]\n";
        return $orig->(@_);
    };
    {
        no strict 'refs';
        no warnings 'redefine';
        *{"${class}::INC"} = $new;
    }
    unshift @INC, $elem;
}

require App::cpanminus::script;
{
    my $old   = App::cpanminus::script->can('install_module');
    my $stack = [];

    sub pp_stack {
        printf "\e[31m%s\e[0m", join qq[->\n], map { $_->[0] } @{$stack};
    }
    my $new = sub {
        my ( $self, $module, $depth, $version ) = @_;
        push @{$stack}, [ $module, $depth, $version ];
        pp_stack;
        my $exit = $self->$old( $module, $depth, $version );
        pop @{$stack};
        return $exit;
    };
    {
        no strict 'refs';
        no warnings 'redefine';
        *{"App::cpanminus::script::install_module"} = $new;
    }
}
unless (caller) {
    my $app = App::cpanminus::script->new;
    $app->parse_options(@ARGV);
    exit $app->doit;
}

Crazy stuff!

Check my fork, a bit less crazy ;)