my $file1 = "C:\\temp\\file1.txt";
my $file2 = "C:\\temp\\file2.bat";

open (FILE1,"$file");
open (FILE2,"$file2");

my @file1 = <FILE1>;
my @file2 = <FILE2>;

close (FILE1);

foreach my $search_string (@file1)
{
    if (grep /$search_string/,@file2)
    {
        while (<FILE2>)
        {
            s/$search_string/"******"/g;
            print FILE2;
        }
    }
}
close (FILE2);