use File::Find;

find(
  sub {
    return unless
      $File::Find::name =~ m{^/var/log/HOSTS/([^/]+)/([^/]+)/(\d+)/(\d+)/(\d+)/(.*)$};

    my( $dir1, $dir2, $year, $month, $day, $file ) =
      ( $1,    $2,    $3,    $4,     $5,   $6    );

    # do stuff with $file
  },
  '/var/log/HOSTS'
);