use strict;
use Data::Dumper;

my $Incoming = 'uno="one" Blah blah dos="two"  * More Noise* tres="three"';
my %att= (PREEXISTING=>"val1", ANOTHER=>"Val2");
my %temp = $Incoming=~m/\W*(\w+)="([^"]+)"/ig;
$att{uc $_}=$temp{$_} for keys %temp;
print Dumper \%att;

#--- Output --
#$VAR1 = {
#          'TRES' => 'three',
#          'UNO' => 'one',
#          'DOS' => 'two',
#          'ANOTHER' => 'Val2',
#          'PREEXISTING' => 'val1'
#        };