Discovering a vulnerability is only half the victory; the real triumph lies in effectively communicating that weakness to those who can fix it. Despite the increasing number of security researchers uncovering critical security vulnerabilities these days, many reports fail to inspire prompt action due to inconsistent reporting.
As a security researcher, you might wonder how to make your findings stand out and catalyze immediate remediation. The answer lies in adopting a universal language that bridges the gap between you and the developers: the Common Weakness Enumeration (CWE) system.
By integrating CWEs into your vulnerability reports, you can level up your reporting game, ensuring your discoveries are understood and prioritized to be fixed.
This approach can really enhance the impact of your work. I’ve seen bug bounty hunters get paid faster and even receive bonuses for the depth of information provided. And I’ve seen internal security testers get raises for consistently helping their dev team to remediate issues more quickly with the addition of CWE details.
In this article, I will show you how CWEs work and how to incorporate them into your vulnerability reports. I’ll even discuss some of the common mistakes you should avoid and how to maximize the impact of your reports.
Let’s get to it…
Understanding CWEs
What is a CWE?
The Common Weakness Enumeration (CWE) is a comprehensive list of software and hardware weakness types maintained by MITRE. It serves as a universal language for identifying and describing vulnerabilities in computer systems. By providing a standardized taxonomy, CWE enables security professionals to communicate more effectively about the nature of software flaws, regardless of the tools or methodologies they use.
Purpose and History
Established in 2006, CWE was created to address the growing need for a common framework to categorize software weaknesses. Before CWE, the lack of standardization led to confusion and miscommunication among security researchers, developers, and organizations.
CWE’s inception aimed to:
- Standardize Vulnerability Descriptions: Provide a clear and consistent way to describe software weaknesses.
- Facilitate Better Tool Integration: Allow different security tools to share information more effectively.
- Enhance Training and Awareness: Serve as an educational resource for understanding common security issues.
Over the years, CWE has evolved to include a wide array of weaknesses, from classic issues like buffer overflows to emerging concerns in hardware security.
CWE vs. CVE: What’s the Difference?
Mixing up CWE and CVE is common, but they serve distinct roles in the cybersecurity landscape.
- CWE (Common Weakness Enumeration)
- Definition: A catalog of software and hardware weakness types.
- Purpose: Helps identify and understand the underlying flaws that can lead to vulnerabilities.
- Example: CWE-79: Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’).
- CVE (Common Vulnerabilities and Exposures)
- Definition: A list of specific security vulnerabilities in software and firmware.
- Purpose: Provides unique identifiers for publicly known vulnerabilities, facilitating easier tracking and reference.
- Example: CVE-2021-44228, which refers to the Log4j vulnerability known as “Log4Shell.”
One way to clarify the differences is that when reporting your vulnerability, you want to determine what weaknesses were detected. If the software or hardware is confirmed to be vulnerable by security triage, then a specific CVE should be produced for the product, and that CVE should link back to the CWE in question.
How to Incorporate CWEs into Your Vulnerability Reports
What comes next is very opinionated. Many others in the industry may not agree with my approach here. But it has served me well over the years.
Identifying the Correct CWE
Step 1: Fully Understand the Vulnerability
Before you can map the vulnerability to a CWE, ensure you comprehensively understand the issue. Make sure you deeply understand how the vulnerability occurs, the affected components, and the potential impact.
Document the steps to reproduce the vulnerability reliably. Better yet, write a proof-of-concept exploit that demonstrates the vulnerability.
And finally, complete an impact assessment to determine the severity and potential exploitation scenarios.
Step 2: Consult the CWE Database
Once you understand the vulnerability, consult the official CWE database at cwe.mitre.org. It includes full search functionality that you can leverage to use keywords to help identify weaknesses.
However, I don’t want you to use that.
Instead, I want you to use the “Software Development View” (CWE-699).
Here’s why.
The CWE catalog has over 900 identified weaknesses, spanning from broad, conceptual flaws to specific, technology-related vulnerabilities. Each precise weakness is typically associated with a more abstract “parent” weakness, which may itself be linked to even higher-level categories, creating a hierarchical structure of interconnected weaknesses.
There are four types of weakness abstractions: Pillar, Class, Base, and Variant.
This picture from MITRE can clarify how they relate:
For vulnerability reports, you want to try to use the Base and Variant abstractions as they cover the technology and language in more detail, and are helpful to developers and security engineers.
This is why the Software Development View is so helpful. CWE-699 organizes a subset of ~400 CWEs around concepts frequently used or encountered in software development. By design, this view is only 2 levels deep. The top level has categories of developer-friendly concepts to facilitate easier navigation. Just remember that you should never map a vulnerability to a CWE Category.
The second level in the view contains Base level weaknesses. This is the starting point where you can map the vulnerability to the appropriate CWE.
Step 3: Match Vulnerability Characteristics
As you explore the categories in CWE-699, read each Base CWE title carefully. If it relates to the characteristics of your vulnerability, click it to get a more detailed view. Under “Relationships”, look to see if a more detailed Variant applies. If not, then the Base CWE may be the best choice. Otherwise, click into the specific Variant and use that.
Pay attention to the detailed descriptions, common consequences, and examples provided for each CWE. Check the related CWEs to ensure you are selecting the most accurate identifier.
Then document your reasoning. Briefly explain why this CWE was selected to aid understanding for everyone.
NOTE: If you are using tooling that supports CWEs look into which ones they are suggesting. SAST tools like SonarQube, Fortify, and Coverity automatically scan code, detect weaknesses, and assign CWE identifiers for you. So do some DAST tools like Burp Suite and OWASP ZAP.
Integrating CWEs without Overwhelming Your Report
Adding in details from the CWE you have identified should not overwhelm your report. Here are a few suggestions to make it easier for you:
- Include the CWE in the vulnerability report summary. For example: “This report details the Use of a Potentially Dangerous Function vulnerability (CWE-676) found in the admin API.”
- Explain the CWE in Simple Terms. Use straightforward language to make your report accessible to both technical and non-technical stakeholders. Be brief and clearly articulate what the CWE means and how it relates to the vulnerability.
- Use Consistent Formatting. Present all CWE identifiers and names in a consistent format throughout the report. Consider dedicating a section to “Associated CWEs” for clarity.
Balancing Technical Details with Clarity
Avoid over-technical jargon. Tailor your language to the knowledge of your audience. Remember you never know who may be reading your report. It’s not always highly technical application security professionals; it could be anyone from junior security triager new on the job to developers who have never seen this class of vulnerability before. When necessary, provide definitions for specialized terms and link to MITRE resources accordingly.
Provide concrete examples. Have a working PoC exploit available when possible. Hell, a sample exploit using cURL is good enough when feasible. Otherwise, include screenshots or screencasts that can demonstrate the exploitation of the vulnerability.
Link to CWE Entries. Direct readers of your vulnerability report to the official CWE page for more in-depth information. This allows interested parties like the developers working on remediation to explore the weakness further without overloading your report.
Additional Tips
Always highlight the impact when possible. Emphasize how the CWE relates to potential risks and business impacts. Use severity ratings or impact assessments aligned with the CWE’s typical consequences.
More importantly, offer remediation advice. You can provide solutions recommended in the CWE entry. Suggest specific changes or practices that can fix the vulnerability, including remediation code.
TIP: If the target’s codebase is published in a source code management system you have access to, do NOT generate a pull request to fix the vulnerability without getting permission from the security and/or development team first. The last thing anyone wants is a security vulnerability disclosed in public before the right stakeholders have had a chance to weigh in on the impact and communication requirements for disclosing the issue.
Common Mistakes to Avoid
Incorporating CWEs into your vulnerability reports can significantly enhance their effectiveness, but it’s important to avoid common pitfalls that can undermine your efforts. Here are some mistakes to watch out for that I have encountered and how to steer clear of them…
Misidentifying CWEs
If you don’t deeply understand the vulnerability enough to identify its characteristics, it’s easy to incorrectly map the wrong CWE to the issue. This can lead to confusion and miscommunication, causing delays in remediation, or worse yet, ineffective fixes. Developers may implement incorrect solutions if the weakness is mischaracterized, leaving the system vulnerable.
When in doubt, seek peer input. Don’t hesitate to discuss your findings with colleagues or within professional forums to validate your choice. On more than one occasion, I’ve helped people on Discord walk through their thinking and recategorize a vulnerability to a more appropriate CWE.
Overcomplicating Reports
With the details that a CWE entry provides, it is easy to include excessive amounts of information and unnecessary details that can overwhelm readers and obscure key points.
You don’t want stakeholders to disengage from overly complex reports, missing critical information.
Keep it concise. Focus on essential information that directly relates to the vulnerability and its impact. Link out to more details on the official CWE site to give those who need or want more information a place to go.
Ignoring the Audience
You need to tailor the content to the reader. Failing to consider the knowledge level and concerns of your audience can reduce the report’s effectiveness.
It may be helpful to include an “Executive Summary” that allows business stakeholders to get a glimpse of the impact to the organization while still providing details in the main report for the technical teams.
Adjust the depth of technical detail based on whether your readers are appsec professionals, developers, managers, or executives. Emphasize the consequences and risks that matter most to each stakeholder group.
And always provide context. Offer background information when necessary to ensure all readers can grasp the significance of your findings.
Overemphasizing CWEs at the Expense of Original Analysis
An over-reliance on CWEs can make reports feel templated and impersonal. Focusing solely on CWEs may omit crucial details unique to the vulnerability you are reporting.
Never lose sight of the specifics based on your own unique analysis.
CWEs lack the foresight to understand the real-world impact of a vulnerability. Discuss potential exploitation scenarios and the actual risk to the organization based on your understanding of the system and resources in play.
Not Providing Actionable Remediation Steps
Vague or unhelpful advice can actually harm your report. Simply identifying a vulnerability without offering solutions can hinder remediation efforts. And without clear steps, those responsible for fixing the issue may be unsure how to proceed.
But the opposite is also the case. In many situations, security researchers may not understand the entire architecture enough to make informed recommendations. It is always safer to make suggestions based on what you can see, and let developers take it from there.
Be humble. And be helpful whenever you can.
Be an advocate for the developers, not an adversary.
Conclusion
In the rapidly evolving landscape of security research, the role of clear and effective communication cannot be overstated. Discovering a vulnerability is only the first step; conveying it in a way that prompts swift understanding and action is where the true impact lies.
By incorporating CWEs into your vulnerability reports, you’re not just adding technical details — you’re adopting a universal language that bridges the gap between security researchers, developers, and organizational stakeholders.
Throughout this guide, we’ve explored how CWEs enhance the precision and professionalism of your reports. You’ve learned how to accurately identify and apply CWEs, avoid common mistakes, and implement strategies to maximize the impact of your findings.
As you continue your vital work in uncovering and reporting vulnerabilities, consider making CWEs an integral part of your reporting process. Doing so strengthens your reports and contributes to a collective effort to improve security practices across the industry.
If you have read this far, I want to thank you for your commitment to security and for striving to make a difference through excellence in vulnerability reporting. It is only by our collective effort will the industry grow stronger.
One last thing…
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