By Minal BopaiahIf you haven’t heard, Target had an extensive breach of its customers’ credit and debit card numbers over the Black Friday weekend, and details are still surfacing.According to The Wall Street Journal, the breach was national in scope and took place through brick-and-mortar stores, not through an online portal. But because customers’ credit and debit card numbers were stolen (presumably by tampering with machines that read the magnetic strip on the back of a card), online merchants will likely be affected.According to our How-To on Minimizing Chargebacks, subscription sites with low price points might be the first to be hit because of “carding,” which occurs when thieves test to see whether the card numbers they’ve swiped are still working or already cancelled by the owner. Because thieves don’t need a physical product, just real-time processing to test if the card works, digital content sites and card-not-present transactions are the most targeted.If you see such activity happening on your site, you can choose to halt card processing for 24 hours after a customer submits an order. That doesn’t mean you should deny access to your site for 24 hours; just be willing to give 24 hours free before collecting your first payment.In addition, the theft means that there will likely be a wave of new cards issued by credit and debit card companies. If you have Account Updater, you can rest assured that your Master Card and Visa users will have their numbers updated automatically. (American Express has a similar program to Account Updater called Continuity Billing). But if you don’t have such technology in place, get ready to update a bunch of accounts. (If you have the tech staff in place, you may want to create an onsite reminder to simplify the updating process.)