Howdy, and welcome to the Monastery!

I've never used Net::LDAP (or any kind of LDAP), but looking at its and Net::LDAP::Filter's documentation, I think that there is no such thing as a flag to ignore whitespace.

Unfortunately filters can't contain regular expressions either (nobody ever takes a cue from Perl, it seems!), but they can use alternation, so you could use (|(extensionAttribute1=$data)(extensionAttribute1=$data )) as a filter and see if that works. Needless to say this will only catch a single whitespace. (And it's untested to boot.)

While I'm commenting, BTW, I really recommend using a module such as Text::CSV for handling CSV files. There's no need to reinvent the wheel, and code such as

my @fields = split "," , $line;
my $data = $fields[5];
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will break in the presence of quoted strings containing commas.