The SWIFT messaging network for cross-border, bank-to-bank transfers has described the theft last year of $81m from Bangladesh’s central bank through fraudulent SWIFT messages as a “watershed event” for the financial-services industry. With the suspected perpetrators—hackers from the “Lazarus Group”—still on the prowl, SWIFT has been urging banks to improve their protection. In the coming days it will issue a new set of minimum security standards, to be implemented this year by its 11,000-plus members. Understandably, few details are being disclosed, but the new standards cover both software and operating procedures. If banks fail to meet them, SWIFT will inform their regulators. Many security experts believe the hackers behind the Bangladesh heist are linked to North Korea; all agree they act with great stealth and sophistication. Other, equally wily outfits are also targeting banks. Keeping them out is arguably the industry’s biggest challenge.