A recent attack on a major retail chain resulted in stolen customer private information, including credit card information.

The report explained that a heating, ventilation, and air conditioning $($HVAC$)$ contractor copied the information to an external hard drive while servicing an air conditioner unit and later uploaded the data to a cloud storage resource.

A security engineer would classify this type of attack as which of the following?

Birthday attack

Supply chain attack

USB cable attack

Cloud$-$based attack