Alexis Kestler
Hi there! As a fellow cybersecurity enthusiast, I know you’ll agree that staying on top of vulnerabilities and risks is critical in today’s threat landscape. This is where CVE and CVSS come in as vital concepts for any security pro to master. Let me walk you through what these key acronyms mean, how they work, and why properly leveraging CVE and CVSS data can power up your vulnerability management to new levels.
What is a CVE?
First, CVE stands for Common Vulnerabilities and Exposures. It is a dictionary of publicly disclosed cybersecurity vulnerabilities, each with a unique ID number. CVEs serve as a common language to describe flaws in software or systems.
The CVE system was launched back in 1999 by MITRE Corporation, the same non-profit that maintains the ATT&CK framework. Since then, CVE has become the industry standard for identifying vulnerabilities with over 160,000 entries and counting!
Each CVE entry includes basic details like:
- CVE identifier number – e.g. CVE-2021-44228
- Brief description of the vulnerability
- When the CVE record was created
- References to security advisories or technical info
You can browse the main CVE List online at cve.org. But enhanced CVE databases like NVD and CVEDetails are better for searching vulnerabilities and digging into technical references.
Now the key thing about CVEs is that they are simply a dictionary of vulnerabilities at a high level. CVEs do not assess the risk or severity of flaws in any way. They just identify and describe vulnerabilities in a common language we all understand.
CVEs by the Numbers
Let‘s look at some key stats on CVEs:
- There are over 160,000 CVEs assigned as of February 2023
- On average, about 16,000 new CVEs were added per year over the last 5 years
- The year 2021 saw a record number of 22,694 new CVEs
- About 60 new CVEs are assigned every working day
- The top vendors with the most CVEs are Microsoft, Apple, Google, Oracle, Cisco, Linux, IBM
As you can see, new vulnerabilities just keep flooding in as software complexity increases. Monitoring new CVEs gives you visibility into what flaws exist so you can assess potential risk.
What is CVSS?
This brings us to CVSS. CVSS stands for Common Vulnerability Scoring System. It is a framework to assign severity scores to vulnerabilities, focused on understanding risk.
CVSS was created by FIRST, an organization focused on improving cybersecurity worldwide. The latest CVSS version is 3.1, which adds updates to stay current.
At a high level, CVSS analyzes three aspects of a vulnerability:
- Exploitability – how easy is it to exploit the flaw?
- Scope – how widespread are the affected systems or components?
- Impact – how much damage can be done if exploited?
It then calculates numerical scores from 0.0 to 10.0 to represent the severity, with 10.0 being extremely critical. There are 3 different CVSS scores:
- Base Score – inherent risk qualities of a flaw
- Temporal Score – evolving real-world indicators
- Environmental Score – customized to your systems
The Base Score is by far the most widely published CVSS rating. Temporal and Environmental scores provide additional context.
CVSS Scoring Scale
Here is how CVSS Base Scores are mapped to severity levels:
| Score | Severity |
| 0.0 | None |
| 0.1 – 3.9 | Low |
| 4.0 – 6.9 | Medium |
| 7.0 – 8.9 | High |
| 9.0 – 10.0 | Critical |
Generally vulnerabilities with a Base Score of 7.0 or higher are the most critical and require priority attention. But any CVSS score should be evaluated in context of your specific systems and tolerance for risk.
CVSS Usage Trends
Looking at NVD data, we can see how CVSS scores break down:
- About 12% of CVEs have no CVSS score assigned
- Around 48% of CVEs fall in the Medium severity range
- Only 10% of CVEs are rated Critical severity
- On average, 750 new Critical CVEs were added yearly over the last 5 years
Although critical vulnerabilities are less common, CVSS helps you quickly identify them among thousands of CVEs. Prioritizing the most severe flaws is key for effective vulnerability management.
Why are CVE and CVSS important?
Now that we’ve covered what CVE and CVSS are, let’s discuss why they matter so much in cybersecurity.
Identification of Vulnerabilities
CVE serves as the core dictionary that gives each known vulnerability a unique identifier that is widely recognized across the industry. Instead of vague descriptions, we can reference specific flaws by their CVE ID.
Risk Awareness
Monitoring newly discovered CVEs provides insight into flaws in the software and systems you use. This awareness of potential vectors helps assess your exposure.
Prioritization Based on Severity
The CVSS scores assigned to CVEs enable you to intelligently prioritize which vulnerabilities pose the most urgent threats. Going after critical risks first is key.
Streamlined Mitigation
Combining a CVE ID with its CVSS score provides the context needed to respond quickly. You can pinpoint flaws, evaluate environment-specific risks, and implement fixes.
Metrics for Managing Vulnerabilities
CVE and CVSS data feeds powerful metrics. For example, you can set goals for addressing X% of critical vulnerabilities within Y days based on CVSS ratings.
Together, CVE and CVSS provide indispensable context for making strategic security decisions and minimizing cyber risks.
Real-World CVEs and CVSS Scores
To really cement your understanding, let me walk through some famous real-world vulnerabilities using their CVE IDs and CVSS ratings:
CVE-2021-44228 – Log4j Remote Code Execution
- CVE ID – CVE-2021-44228
- CVSS – 10.0 (Critical)
- Summary – Remote code execution in Log4j logging library
- Impact – Full server compromise remotely
This extremely severe Log4j vulnerability put countless organizations at massive risk until patched. The critical CVSS rating quickly alerted security teams to prioritize fixing this ubiquitous logging component.
CVE-2017-0144 – EternalBlue Exploit in SMB
- CVE ID – CVE-2017-0144
- CVSS – 8.1 (High)
- Summary – Remote code execution via SMB
- Impact – Wormable attack; enabled major outbreaks like WannaCry ransomware
This high severity Windows SMB flaw enabled worms which spread globally causing massive disruptions before patches were available. The CVSS score highlighted the urgency to apply fixes.
CVE-2014-6271 – Shellshock in Bash
- CVE ID – CVE-2014-6271
- CVSS – 10.0 (Critical)
- Summary – Remote code execution via environment variables in Linux/UNIX Bash shell
- Impact – Complete compromise of unpatched servers
This critical remote code execution vulnerability sent shockwaves through the Linux/UNIX world. The maximum CVSS rating left no doubt that patching was an emergency.
As you can see from these examples, the CVE ID pinpoints the specific flaw, while CVSS clarifies the severity level to drive urgent action.
How to Leverage CVE and CVSS
Here are some tips to leverage CVE and CVSS more effectively in your security programs:
Monitor New Vulnerabilities Daily
Make checking for new CVEs part of your daily or weekly vulnerability monitoring routine. Subscribe to email alerts from CVE Numbering Authorities or vulnerability databases.
Focus on CVSS 7.0+ Vulnerabilities
Filter vulnerabilities by CVSS scores and zero in on those with ratings of 7.0 or higher, indicating high/critical severity.
Cross-Reference Vendor Advisories
Vendor security advisories will often reference relevant CVE IDs and severity ratings. Combine vendor alerts with CVE/CVSS data.
Search CVE Databases
Frequently search CVE databases like NVD to find vulnerabilities by keyword, CVE ID, or CVSS score.
Include CVE IDs in Documentation
Reference CVE IDs prominently in vulnerability remediation processes, progress reports, and security documents.
Incorporate CVE/CVSS Into Tools
Integrate CVE and CVSS data feeds into security tools like vulnerability scanners and ticket trackers.
Educate Your Team
Train developers, sysadmins, and security analysts on properly interpreting and leveraging CVE/CVSS.
Consistently applying these best practices helps minimize blind spots and maximize risk reduction.
Key Takeaways on CVE and CVSS
Let‘s recap the key lessons on CVE and CVSS:
- CVEs identify and describe known vulnerabilities with a standard numbering scheme.
- CVSS evaluates the severity of vulnerabilities on a 0-10 scale based on multiple metrics.
- Prioritizing vulnerabilities for remediation based on CVSS scores enables risk-based allocation of resources.
- Monitoring CVE/CVSS helps security teams respond quickly to fix critical flaws.
- Organizations should leverage CVE/CVSS across vulnerability management programs for optimal results.
I hope this overview has helped demystify these two cornerstones of modern vulnerability analysis. Properly understanding and leveraging CVE and CVSS data will boost your ability to intelligently assess and manage cyber risks.
The key is combining identification of flaws via CVE with prioritization based on CVSS severity ratings. This powers effective vulnerability remediation and risk reduction. By adopting CVE/CVSS best practices, you can tackle vulnerabilities like a pro!
