0 to 1 on EPSS

About this episode

Jay Jacobs didn't set out to rewrite vulnerability prioritization—he set out to keep working on data he loved. After helping build Verizon's DBIR alongside Wade Baker, the two spun up Cyentia Institute to do the same kind of research without Verizon attached to it. Two of Cyentia's earliest customers happened to be holding opposite halves of the same puzzle: Kenna had scan data and vulnerability sightings across hundreds of companies, and Fortinet had detections of what attackers were actually exploiting. "What if we bring this together?" turned into a side experiment, then a Black Hat paper, then EPSS—and eventually into Empirical Security, where Jay is Chief Data Scientist to give the score a permanent home. In this episode, Jay tells Mehul the full arc: why only two to five percent of vulnerabilities ever get exploited and what broke his "food supply" theory of attacker behavior, why CVSS is really measuring a practitioner's perception of how bad a vector string looks, the delicate conversations at Kenna about giving away a proprietary score, and the naming theory behind making "EPSS" rhyme with the thing it was replacing. He also gets specific about the machinery—why Metasploit is a strong signal and Exploit-DB is a weak one, why nobody hand-assigns weights, where the "23% more accurate" stat in v5 actually comes from—and closes with the gun-to-the-head threshold answer that surprises almost everyone who hears it: not 0.9, but 0.03