use warnings;
use strict;

use XML::TreeBuilder;

my $xml =q(<?xml version="1.0"?>
 <response>
  <files>
   <file file_url="http://server.domain/file1.exe">
    file1.exe
   </file>
   <file file_url="http://server.domain/file2.zip">
    file2.zip
   </file>    
  </files>
 </response>
);

my $tree = XML::TreeBuilder->new ();

$tree->parse ($xml);

my @fileElts = $tree->find ('file');
my %file_url;

$file_url{$_->attr ('file_url')} = $_->as_text () for @fileElts;

print "$_: $file_url{$_}\n" for keys %file_url;

##</code><code>##

http://server.domain/file2.zip: 
    file2.zip
   
http://server.domain/file1.exe: 
    file1.exe