A series of DDoS attacks in April targeted online payment processing firms Authorize-IT and 2Checkout. Both those attacks were later attributed to extortion schemes in which attackers threatened to knock the firms’ web sites offline. Authorize.net’s statement included no information about the motivations of the attackers. All three firms are widely used by small web hosting companies and other online merchants who need to accept credit cards but don’t have their own merchant account.

Authorize.net said it “employs a number of industry standard hardware and software tools and strategies as a defense against DDoS attacks,” but was “implementing additional technology solutions, engaging with industry experts in the area of DDoS attacks and working with law enforcement officials.”