Como você relata e corrige as descobertas do XSS para seus clientes ou partes interessadas?

Starting with detailed description about XSS, what's it? why does it happend, Mention the vulnerable endpoint which needs to be remediated. Also Mentioning highest possible Impact Write step by step proof of concept that anyone, even non technical staff, can follow it and reproduce the vulnerability. Offer remediation depending on the backend language , if there's a packages which could filter it out like HTMLencode, Dom purify , etc.. Or manually should be filtered using black and white list (White list is preferred)

An XSS report should provide a comprehensive overview of the findings, the impact, and the evidence of the vulnerability. This should include a summary of the scope, objectives, and methodology of the test, as well as a description of the XSS type and the affected parameter, URL, or input field. Additionally, you should include a screenshot or video of the exploit to demonstrate the injected code and resulting output. Furthermore, it is important to explain the impact and potential scenarios that an attacker could leverage, as well as rate the severity and likelihood of the vulnerability based on a standard scale such as CVSS. Lastly, provide a reference to a reputable source that explains the vulnerability and its mitigation.

An XSS report should include a clear description of the vulnerability, the steps to reproduce it, the potential impact, and remediation recommendations. It should also include any relevant screenshots or code snippets.

Include the detailed description, explaining what is vulnerable and why (exact injection point on specific endpoint). Explain what could be the highest impact. Write step by step proof of concept that anyone, even non technical staff, can follow it and reproduce the vulnerability.

Generally speaking, I've never had a report that was just for XSS. That said, all findings, especially XSS, should include: - Steps to reproduce the XSS finding - Screenshots to prove you exploited an XSS vulnerability - Recommendation(s) on remediation - Severity/Criticality Level - URL where the vulnerability exists - CVE, if available - CVSS score - Impact - other data points your client feels are applicable to their organization.

Impact of an XSS vulnerability 1. XSS Explained:XSS allows attackers to inject malicious code into a website. Example: Imagine a hacker altering your site to steal user credentials." 2. Business Impact:XSS compromises user data, harms trust, and damages the brand.Legal penalties and financial losses are possible. 3. Urgency:Fix this critical vulnerability promptly. 4. Legal and Ethical Reminder:Addressing XSS is essential for data protection and ethical practices.

The impact of XSS should be communicated in terms of potential harm to the business or users. This could include unauthorized access to sensitive data, defacement of the website, or other malicious activities.

When evaluating XSS impact, take into consideration any effective controls that may be mitigating certain attack types. Is a content security policy set? Is it set correctly? Is httponly set on all cookies? Generating an alert box does not equal stealing a user's cookies, and hinting at the possibility of doing so when controls are clearly in place to mitigate the risk will hurt the trust of your reporting.

In conveying the gravity of XSS vulnerabilities, I've found that storytelling resonates well with stakeholders. For instance, during a client engagement in the financial sector, we uncovered an XSS flaw in their online banking portal. By illustrating how an attacker could inject malicious scripts to hijack customer sessions and steal sensitive financial information, we painted a vivid picture of the potential repercussions. I emphasized the urgency of addressing the issue promptly to safeguard their customers' trust and avoid regulatory penalties. Utilizing plain language and relatable examples, I underscored the imperative for immediate action and underscored the potential reputational damage and financial losses if left unaddressed.

Explain potential consequences (data theft, account takeover, etc.) Highlight affected user data or functionality Provide real-world examples or scenarios

If technology stack of the web application is identified or previously known, the penetration tester should tailor the recommendation and include a specific function to be called which must encode the user input to prevent it from being rendered as an active element. While this approach works in most of the cases, it would break the HTML editors throughout the application because the user’s input is encoded. In this case, the input should be sanitized in order to remove: - “script” HTML tags - all JavaScript event handlers Additionally, implementing a secure Content-Security-Policy response header would be a plus. It should forbid inline JS from being executed, and also forbid the import of external scripts to only trusted domains.

Remediation recommendations should be specific and actionable. This could include input validation, output encoding, use of HTTP-only cookies, and updating or patching any vulnerable software.

To provide effective remediation recommendations for XSS: General Guidelines: Recommend practices like input validation, output encoding, and implementing CSP. Specific Solutions: Provide actionable steps such as code modifications or configuration changes. Include Examples: Offer code snippets or configuration examples to illustrate implementation. Verification Method: Suggest a way to verify the effectiveness of the solution. Reference Reliable Sources: Link to OWASP or similar for detailed guidance and additional information.

In addition to specific remediation recommendations for XSS vulnerabilities, it's important to promote a culture of security awareness within the organization. This can be done by providing training for developers on secure coding practices and the importance of web security. Regular security audits and code reviews can help catch vulnerabilities early. Using automated security testing tools can also make it easier to find XSS issues and other security problems. By focusing on education and proactive measures, organizations can better protect themselves against XSS and similar threats.

The best approach to remediation is 1. Give a general approach about how to fix, for example : filter inputs 2. Give a specific example, for example : Use a specific function in PHP that filters the input So That you give them hint with example, but not limiting them to a specific solution.

Regular follow-ups are important to ensure that the recommended actions have been taken and that the vulnerability has been effectively mitigated. This could involve re-testing the application or conducting a full security audit.

From my experience, the key to effective follow-up on XSS findings lies in maintaining clear communication channels and providing ongoing support to clients. After presenting our XSS report, we established regular check-ins to address any questions or concerns and offer guidance on implementing remediation measures. We emphasized the importance of conducting thorough retests post-remediation to ensure the vulnerabilities were adequately addressed. By fostering a collaborative approach and providing comprehensive documentation, we facilitated a smoother remediation process and instilled confidence in our clients' security posture.

The best follow up is the follow up which 1. You support the developer in fixing the vulnerability 2. Explain the finding further if needed 3. Retest the vulnerability to ensure fixing works

We can follow up with developers by providing assistance as they work on fixing the XSS vulnerabilities. We can explain use of security headers and secure coding practices. Once the XSS vulnerabilities have been addressed, conduct thorough testing to verify that the fixes are effective. Re-test the affected pages and input fields to ensure that they are no longer vulnerable to XSS attacks.

Following up on XSS findings is a crucial final step in your report. I believe you should ensure that your clients or stakeholders have received and understood your recommendations. Establishing a clear communication channel and offering support for any questions they may have is essential. Additionally, conducting a retest or verification scan to confirm that the issues have been resolved and that no new vulnerabilities have emerged is important. Documenting the results of this retest and providing a final report summarizing the findings, remediation efforts, and any improvements made is key. I think that by implementing this follow-up process, you can reinforce accountability and help maintain a strong security posture.

A good penetration tester would demonstrate the impact by providing clear reproduction steps, using carefully crafted payloads to maximize the impact. Executing “alert(1)” is simply not enough - it proves nothing to the client. Proof of concept must be carefully crafted in order to demonstrate one of the following attacks: - stealing session cookie or token - session-ride your way to sensitive “gadget” API calls in order to change the user’s email or password (in case it does not require current password) - modify the DOM of the page to show a phishing page, sending the entered credentials to your webserver - extract the contents of the victim’s DOM

As a penetration tester, I believe it’s essential to continually improve your XSS reporting skills to deliver value and build trust with clients and stakeholders. Seeking feedback from peers, mentors, or supervisors can provide valuable insights based on their experience. Staying updated on the latest trends, tools, and techniques for XSS testing and reporting is also crucial for enhancing your skills. Additionally, reviewing your own reports to identify strengths, weaknesses, and areas for improvement can help you refine your approach. By actively pursuing these strategies, you can become more effective in your reporting and contribute to stronger security practices.

To improve your XSS reporting skills: Seek Feedback: Get input from peers, mentors, or supervisors. Stay Updated: Keep abreast of trends, tools, and techniques in XSS testing. Self-Review: Evaluate your own reports to identify strengths and weaknesses. Continuous Learning: Learn from experience and update your skills accordingly.

Continuous learning and staying updated with the latest security trends and best practices are key to improving your XSS reporting skills. Participating in security forums, attending workshops or webinars, and obtaining relevant certifications can also be beneficial.

Continue learning to exploit all the types of XSS on Portswigger Academy or other similar online labs. Blind XSS can be often missed. Keep on top of latest trends or tools for example Portswigger released a new tool called DOM Invader which is a browser tool installed in Burp's inbuilt browser. It assists in detecting DOM XSS vulnerabilities using various sources and sinks, including web messages and prototype pollution.

Always ensure that your testing and reporting activities are conducted ethically and with proper authorization. Also, remember that while XSS is a serious vulnerability, it is just one of many potential security issues. A comprehensive security strategy should consider all aspects of application security. Remember, effective communication is key when reporting XSS findings. The goal is not just to identify vulnerabilities, but to provide the necessary information and guidance to help your clients or stakeholders mitigate these vulnerabilities and enhance their overall security posture. It’s important to present your findings in a clear, understandable manner and to provide actionable recommendations for remediation.

Continual education and awareness are paramount in the fight against XSS vulnerabilities. In addition to addressing immediate concerns, I advocate for ongoing training sessions and workshops to empower stakeholders with the knowledge and skills needed to identify and mitigate XSS risks proactively. By fostering a culture of security awareness within organizations, we can cultivate a collective vigilance against emerging threats. Furthermore, integrating security testing into the development lifecycle enables early detection and mitigation of vulnerabilities, minimizing the likelihood of XSS issues surfacing in production environments

Learn to chain vulnerabilities thus increasing the risk example XSS + CSRF: By combining these, an attacker can create a malicious payload that, when executed by a victim with an active session, performs unauthorised actions on a target website. This could include changing account settings, making financial transactions, or even initiating actions with elevated privileges. Others to consider, XSS + SSRF, XSS + Open Redirects, XSS + SQL Injection. It can also go the other way as well for example Open redirect to XSS.

Take into account legal and compliance implications, integrate findings into existing security processes, and prioritize education and awareness efforts for developers and users.