A North Korea-sponsored hacking group is believed to have stolen the credit card information of shoppers who purchased products from certain American and European online stores for more than a year.

Dutch cyber security firm Sansec said Monday that hackers linked to the "APT Lazarus/HIDDEN COBRA” group were found to have hacked into online stores for digital payment "skimming" from as early as May 2019.

Digital skimming involves intercepting credit card information during online store purchases by implanting a malware code.

The affected retailers include international fashion chain Claire's, camera retailer Focus Camera and jewelry seller Wings Jewelry and Gifts.

The company assessed that North Korea, whose hacking mostly involved banks and the South Korean cryptocurrency markets, has extended its portfolio to digital skimming.