The other monks have the regex solution covered, but here's the non-regex version.

my $str = 'CTTCTTCTTCTT';
my $pat = 'CTTCTT';
my $pos = 0;
while (($pos = index($str, $pat, $pos)) >= 0) {
   print $pos, "\n";
   $pos++;
}
__END__
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