How can you prepare for a zero-day attack

On Nov. 24, 2021, an Alibaba Cloud Security engineer noticed that a certain string of text, when inserted into Java’s logging utility Log4j, could execute remote code.

Cue the alarms, as vendors, security experts, and end-users spread the word about the hole in the massively used software, including US Secretary of Homeland Security Alejandro Mayorkas.

Companies had no time—ahem, zero days—to fix the problem, as a race began between patch-makers and threat actors looking to exploit the open systems. The industry-wide distress signal aimed to prevent the zero-day vulnerability from becoming a zero-day attack. But what exactly is a zero-day attack?