Federal flaw database commits to grading system
My vuln is worse than yours
A federal database of software vulnerabilities funded by the US Department of Homeland Security has decided on a common method of ranking flaw severity and has assigned scores to the more than 13,000 vulnerabilities currently contained in its database, the group announced last week.
The National Vulnerability Database, unveiled in August , completed its conversion over to the Common Vulnerability Scoring System , a industry initiative aimed at standardizing the severity rankings of flaws. The CVSS gives vulnerabilities a base score based on their severity, a temporal score that measures the current danger - which could be lessened by a widely available patch, for example - and an environmental score that measures an organization's reliance on the vulnerable systems.
"There does not exist or ever will exist a perfect technique for scoring vulnerability impact," Mell said. "CVSS appears to work very effectively and it was better than my current scoring system and so it made sense to adopt it."
The move to the Common Vulnerability Scoring System gives the flaw-ranking initiative a major boost. Created by security researchers at networking giant Cisco, vulnerability management software provider Qualys and security company Symantec, the CVSS has not been used widely, though many companies are considering scoring flaws with the system. (SecurityFocus is owned by Symantec.)
The grading of the previous vulnerabilities on the CVE list solves a problem that hampered adoption of the Common Vulnerability Scoring System, said Gerhard Eschelbeck, chief technology officer for Qualys and one of the founding members of the CVSS team.
"With the introduction of CVSS as a standardized vulnerability scoring system, the question appeared, how do we go back and score all the historical vulnerabilities released?" he said. "It is very encouraging to see NVD has taken on this big task, providing comprehensive CVSS scoring for even historical vulnerabilities."
To date, no software vendor has yet graded vulnerabilities in its product using the Common Vulnerability Scoring System. Microsoft, for example, has its own severity-grading system and has considered but not committed to supporting the CVSS. Microsoft's current scoring system - rating flaws as one of four levels of severity - works well for its customers, said a spokesperson for the software giant. The company did not rule out a future move to the ranking system, however.
Some software makers worry that rating vulnerabilities could have some legal implications. For example, if a company gave a flaw a low rating and then that issue was used as an avenue for a costly attack, the firm could be held liable for its severity ranking. Such worries have caused companies to take their time debating the merits of adopting the Common Vulnerability Scoring System, said Gavin Reid, team lead for the CVSS program at the Forum of Incident Response and Security Teams (FIRST) , which was chosen to host the CVSS project.
"I think there is significant hurdles for people adopting the scoring system," said Reid, who also works for Cisco, one of the companies that supported the creation of the CVSS. "But once one or two of them start using it, I think we will see a lot more adopting CVSS."
For that reason, the National Vulnerability Database's decision to use the scoring system and the group's ranking of more than 13,000 previous vulnerabilities has given CVSS a major boost, Reid said.
The NVD is managed by National Institute of Standards and Technology (NIST)  but funded through the Department of Homeland Security. The group's staff adds 16 new vulnerabilities to the the database each day, up from 8 per day in August , and keeps a variety of current statistics, including a measure of the workload that the release of such flaws has on network administrators.
The National Vulnerability Database (NVD) is an initiative funded by the US Department of Homeland Security to boost the preparedness of the nation's Internet and computer infrastructure, as called for by the Bush Administration's National Strategy to Secure Cyberspace . Other DHS initiatives, such as the US Computer Emergency Readiness Team (US-CERT) , release some information on serious vulnerabilities, but do not try to create a complete collection of critical and non-critical flaws.
The NVD piggybacks on the Common Vulnerability and Exposures (CVE) to do just that. The CVE, a listing of serious vulnerabilities maintained by the Mitre Corporation, expands on the Internet Catalog (ICAT)--a previous NIST project--that archived the vulnerabilities defined by the Common Vulnerability and Exposures list.
The NVD team scored the vulnerabilities using an automated process. The CVE database only had about 80 percent of the information needed to give an exact score, Mell said, so the group has generated the scores based on the information at hand and labeled each one "approximate."
The CVE definitions are one of the standards that the National Vulnerability Database depends on. The database also uses the Open Vulnerability and Assessment Language (OVAL) to describe the security issues in a standard language, NIST's Mell said.
"The reason we chose CVSS as opposed to another scoring system was that we believe in standards," Mell said. "If everyone uses a different scoring system, then the effectiveness of each scoring system is limited."
Currently, the database gets nearly 1.5 million hits a month from the private sector as well as government and academic users, Mell said. The group also provides a calculator for companies to generate an environmental score based on the vulnerable systems and the company's use of those systems.
Copyright © 2005, SecurityFocus 
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