use strict;
use warnings;

use Data::Dumper;

my $s = q{   ABC: 123 xyz: 100    def: YYY    aaa: ZZZ};

my %extract =
   map { split m{\s*:\s*} }
   split m{(?<!:)\s+}, $s;

print Data::Dumper->Dumpxs( [ \ %extract ], [ q{*extract} ] );