There are a number of ways of going about providing a solution to your problem. I have gone for a simple regex;

#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dumper;

my @lines = ( "[HAVE 1324,2,32,324,5,643]", "[HAVE 4,213,5432,4]");
for my $line (@lines) {
    my @numbers;
    while ($line =~ /(\d+)/g) {
        push @numbers, $1;
    }
    print Dumper \@numbers;
}
[download]

Produces the following output;

$VAR1 = [
          '1324',
          '2',
          '32',
          '324',
          '5',
          '643'
        ];
$VAR1 = [
          '4',
          '213',
          '5432',
          '4'
        ];
[download]

You could use s/// to remove the extra characters and use split on the commas if you like.