Sparrowvsrevolution writes "Maybe instead of zero-day vulnerabilities, we should call them -312-day vulnerabilities. That's how long it takes, on average, for software vendors to become aware of new vulnerabilities in their software after hackers begin to exploit them, according to a study presented by Symantec at an Association of Computing Machinery conference in Raleigh, NC this week. The researchers used data collected from 11 million PCs to correlate a catalogue of zero-day attacks with malware signatures taken from those machines. Using that retrospective analysis, they found 18 attacks that represented zero-day exploits between February 2008 and March of 2010, seven of which weren't previously known to have been zero-days. And most disturbingly, they found that those attacks continued more than 10 months on average – up to 2.5 years in some cases – before the security community became aware of them. 'In fact, 60% of the zero-day vulnerabilities we identify in our study were not known before, which suggests that there are many more zero-day attacks than previously thought — perhaps more than twice as many,' the researchers write."