By Robert Lemos
4th December 2005
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
"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
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
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 =A9 2005, SecurityFocus
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