a scam or dishonest scheme to gain benefit from systems that either allow it on a technicality or have no way of stopping it

This word is generally used in phrases like rorting the system, a rort at tax-payers' expense, That's a complete rort!. It implies that the rorter is abusing a privilege or getting something for nothing, or defrauding some organisation of money. The meaning is similar to scam, but a scam is usually at the expense of ordinary people whereas a rort is at the expense of a government, company or other organisation.