In an email to affected customers, the company said attackers may have accessed email addresses and hashed passwords stored in its customer files. Simian says on its website that it serves around 500,000 customers across its three brands Reclameland, Drukland and Flyerzone. It has not said how many were affected by the breach, but that only a small number of customers had their credit card details intercepted. Simian said it had reported the breach to the Dutch data protection authority AP and filed a report with police. The attack is the latest in a run of data breaches at Dutch companies, following the CEVA incident and, earlier this year, a mass hack at telecoms provider Odido.