Known vulnerabilities are No.
Winkler, author of Corporate Espionage and the forthcoming book Security for System and Network Administrators due out in March, recently revised his estimate of the number of hackers, saying there now are 50,000 to 100,000 worldwide - up from an estimated 35,000 to 50,000 two years ago. They are mostly teenagers who know how to exploit known vulnerabilities, according to Winkler. Beyond that, the number of hackers who are good enough to write their own tools has grown from 1,000 to somewhere between 5,000 and 10,000, and the number of most highly skilled hackers now stands at about 1,000. These are people who like to play with software and figure out how to find exploits into the software. That requires lots of good technical talent and knowing how to do software testing.