How good are you at scoring security vulnerabilities, really? Boffins seek infosec pros to take rating skill survey

January 8, 2021 TH Author

A German academic is running a study into the effectiveness of vulnerability scores – and is hoping the research will shed more light on the occasionally controversial system.

By running a survey on whether infosec bods think the Common Vulnerability Scoring System (CVSS) is a useful tool for assessing security flaws, Dr Zinaida Benenson of Friedrich-Alexander Universität Erlangen-Nürnberg’s IT Security Infrastructure Lab in Germany hopes to further the infosec world’s understanding of how reliable the system really is.

While the survey hopes to gain up to 300 respondents, Benenson was coy about precisely what she’s hoping to prove or disprove, but she did drop The Register a hint about the current state of CVSS scoring.

In preliminary research, Benenson and her fellow researchers asked a handful of infosec bods to allocate CVSS scores to 10 sample vulnerabilities, as a way of testing how consistent their scoring was.

“I’m not naming the vulnerabilities, because some of them are now in the survey, but just to give you a feeling…” she said, sending us a partial table of scores from that exercise:

vuln 1: 4.7, 5.4, 6.1, 6.3, 7.3, 7.5
vuln 2: 3.0, 4.8, 5.0, 5.4, 6.5, 7.1, 7.6, 8.4
vuln 3: 4.7, 6.8, 7.2, 8.2, 9.0, 9.8
[...]
vuln 7: 3.1, 4.2, 4.8, 5.3, 6.5, 7.5, 8.3, 9.3
[...]
vuln 10: 0.0., 3.7, 5.3, 8.2, 8.8

“Some of the scores were of course the same for different experts, but on the whole, there wasn’t much agreement,” Benenson added. “And I’m not picking especially weird vulnerabilities, all 10 of them were rated like this.”

The CVSS survey can be found here.

CVSS was invented in 2005 when Cisco, Microsoft, Qualys, Symantec and others joined forces to announce the scoring system we all know and, er, love. In the decade-and-a-half since then, CVSS has become the standard at-a-glance measure of a given vulnerability’s severity, with the worst reaching 10.0 on the system’s ten-point scoring scale.

Scores are commonly allocated to vulnerabilities along with a Common Vulnerabilities and Exposure (CVE) number, which has led to the undesirable practice of researchers “collecting” high-severity CVEs by using dubious methods.

A recent example of a 10.0-rated CVEs was a VMware vCenter vuln that allowed anyone at all to remotely create an admin-level account. Lower down the scale, but still significant, was a CVSS 7.8-graded flaw in ConnectWise’s Automate product that allowed someone with user credentials to remotely run commands on an Automate instance.

Referring to the table of varied CVSS scores she showed us, Benenson said: “We are not saying that CVSS experts are not skilful. We are trying to find factors behind the fact that the scores are so different. Actually, the scores are supposed to be the same across different actors; this is the idea of CVSS.” ®