I heard an interesting question the other day: What’s the difference between a vulnerability scanner and a SIEM? Qualys and Nessus are examples of vulnerability scanners. Arcsight and Splunk are examples of SIEMs.
To a security practitioner, the tools couldn’t be much more different, but not everyone is a security practitioner.
On a basic, fundamental level, a vulnerability scanner deals in what’s missing in the environment and what could happen as a result of those things that are missing. A SIEM deals in what actually has happened and is happening.

David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.
