The 21 signatories support a number of steps, such as banning vendors who behave illegally, in a document agreed to last week in Paris.

CISA's director said that the vulnerability "is one of the most serious I've seen in my entire career, if not the most serious."

The $2 billion Austrian firm said on its website that an "ongoing" incident was affecting its ability to process orders.

The attacks were anything but unique. Still, they worked.