WAF Bypass

WAF Bypass

Overview of the Vulnerability

A Web Application Firewall (WAF) protects applications from attacks such as Cross-Site Scripting (XSS), SQL injection, and malicious strings using pattern matching and traffic analysis. Some applications will completely rely on WAFs as their primary defense. By bypassing the WAF, an attacker can gain direct access to an application’s server via a specifically crafted payload.

Business Impact

WAF bypass can result in reputational damage and indirect financial loss for the business through the impact to customers’ trust in the application’s security of user accounts. If an attacker successfully gains direct access to the server it can lead to user account compromise and data exfiltration.

Steps to Reproduce

1. Use a browser to navigate to: {{URL}}

2. Access the application by sending the following payload to the endpoint {{value}}:

{{payload}}

Proof of Concept (PoC)

The screenshot(s) below demonstrates the WAF bypass:

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Guidance

Provide a step-by-step walkthrough with a screenshot on how you exploited the vulnerability. Your submission must include evidence of the vulnerability and not be theoretical in nature. This can be using a screenshot of both pages side by side with the address bar in the screenshot, or if the domain is not protecting its IP Address, a DIG showing the record for the domain and IP Address.

Describe what the impact of the WAF bypass and what an attacker can achieve after bypassing it. Do not access or attempt to access sensitive information. Do not access Personally Identifiable Information (PII).

Recommendation(s)

Deploy WAFs following best practices and ensure it is configured to protect the web application from common exploits. Additionally, enable logging and monitoring of traffic.