I'd do it this way:

use strict;
use warnings 'all';
use Regexp::Common;

while (<DATA>) {
    if (/$RE{net}{MAC}{hex}{-sep => '-'}{-keep}/i) {
        print "New string is: ", substr ("$5$6$7" => 1), "kk\n";
    }
}

__DATA__
Physical Address. . . . . . . . . : 00-B0-D0-87-52-19
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.45.10.166
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Abigail