Previously unknown “zero-day” software vulnerabilities are mysterious and intriguing as a concept. But they’re even more noteworthy when hackers are spotted actively exploiting the novel software flaws in the wild before anyone else knows about them. As researchers have expanded their focus to detect and study more of this exploitation, they’re seeing it more often. Two reports this week from the threat intelligence firm Mandiant and Google’s bug hunting team, Project Zero, aim to give insight into the question of exactly how much zero-day exploitation has grown in recent years.
Mandiant and Project Zero each have a different scope for the types of zero-days they track. Project Zero, for example, doesn’t currently focus on analyzing flaws in Internet-of-things devices that are exploited in the wild. As a result, the absolute numbers in the two reports aren’t directly comparable, but both teams tracked a record high number of exploited zero-days in 2021. Mandiant tracked 80 last year compared to 30 in 2020, and Project Zero tracked 58 in 2021 compared to 25 the year before. The key question for both teams, though, is how to contextualize their findings, given that no one can see the full scale of this clandestine activity.