, SecurityFocus 2006-07-07
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Some security experts have doubts whether the model will ever be able to make better than a rough estimate of the number of vulnerabilities that will likely to be found in a particular application.
The prediction of the number of vulnerabilities from general trend data may gloss over too many important details to be of real value, said Gerhard Eschelbeck, chief technology officer for anti-spyware firm Webroot Software.
"This is a little bit like predicting the next earthquake," Eschelbeck said. "It's a valuable area of research but it may not, in the end, be practical."
Because vulnerability researchers' interest in finding flaws in a particular product can be fickle, general trends could be swamped by other variables. In July, for example, Microsoft's Internet Explorer browser will likely see an uncharacteristically large number of vulnerabilities found because one researcher has decided to release a bug each day of the month. Market forces could also throw off the models, since a handful of companies now pay for previously unknown flaws, a situation that could cause researchers to stay interested in older operating systems.
Moreover, the discovery of less serious flaws is far less important than critical vulnerabilities that could lead to remote compromises, Eschelbeck said.
"It is not just about the number, but about the severity," he said. "Just the pure number does not mean a lot without the context."
If such limitations could be overcome, the ability to predict the future number of software flaws could have big benefits, said Brian Chess, chief scientist with source-code analysis tool maker Fortify. For example, the assumption that vulnerabilities will always be present in software may suggest a better strategy for dealing with the issues. Developers can choose to put their resources into finding the more serious issues, he said.
"If you accept that flaws can't be gotten rid of, you can decide which mistakes you are going to make and which ones are not acceptable," Chess said, "Even though you cannot predict which line of codes will have the vulnerabilities, you can push the actual class of vulnerabilities one way or another."
In the end, even if the research does not produce accurate predictions, accepting that you will have security problems and learning to deal with the aftermath of releasing a software product are important lessons, he said.
"The next thing you build will have security problems just like the last thing you did, but let's make sure that when we have a vulnerability, we can deal with it," Chess said. "I think that is an evolution in the way that people think about building security into their software."