my $datafile=<file with binary data>;
my $searchdata=<file with string to be replaced>;
my ($FH,$buf, $cut);
binmode($FH);
open ($FH, $datafile);
read($FH, $buf, 10000);
chop($buf);
close ($FH);
open ($FH,$searchdata );
read($FH, $cut, 100);
chop($cut);
close($FH);
my $result = index($buf,$cut);
print "position: $result\n";