Linked article pretty much said...
Feb. 3 JAL has made a statement that there have been unauthorized login of some of JMB accounts. Some miles were exchanged to Amazon.com gift cards and as of Feb. 2 JAL has identified total of several hundred thousand yens worth of unauthorized Amazon.com gift cards were issued from seven JMB accounts. JAL is also suspecting additional 60 or so JMB accounts were affected and miles were stolen in some form.
JAL has indicated that somebody has obtained passwords of JMB accounts which were affected. JAL has not made a statement regarding how passwords were stolen. JAL has reported the incidents to the police, and meanwhile JAL has temporary suspended Amazon.com gift card exchange from JMB and asked Amazon.com to void gift cards involved in unauthorized log in of JMB accounts.