jsDelivr Content-Security-Policy Bypass Scanner

jsDelivr is a popular open-source Content Delivery Network (CDN) used extensively by web developers for hosting and serving web files such as JavaScript libraries, CSS files, fonts, and images. It is backed by multiple CDN providers to ensure reliability and speed and is widely utilized in projects ranging from personal websites to substantial corporate applications. Although highly beneficial for enhancing page speed and reliability, its improper use or configuration can expose applications to security vulnerabilities. The distribution and wide adoption of jsDelivr require stringent adherence to security practices to prevent exploitation. Inadequate security measures could lead to significant vulnerabilities being injected into applications through CDN files. Ensuring secure usage involves both developers and security teams working closely to maintain the integrity and security of web applications.

Cross-Site Scripting (XSS) vulnerabilities involve the injection of malicious scripts into trusted websites, compromising user data. The vulnerability occurs when an application includes untrusted data without proper validation or escaping, allowing attackers to execute scripts in a user's browser. Exploiting this vulnerability can lead to unauthorized access to session tokens, cookies, and other sensitive information. XSS attacks can alter the content and behavior of the pages, potentially redirecting users or altering site content without their knowledge. Ensuring effective Content Security Policy and proper input validation are critical measures in mitigating the risk of XSS. Organizations must employ comprehensive security measures to monitor and prevent such vulnerabilities effectively.

The identified vulnerability leverages the jsDelivr service to bypass Content Security Policy (CSP) protections, allowing for XSS attacks. It primarily targets web pages implementing insufficient CSP, where the 'Content-Security-Policy' header is improperly configured. An attacker can initiate this bypass by injecting specific script sources, such as those hosted on cdn.jsdelivr.net, into vulnerable endpoints. This bypass can be executed by exploiting endpoints where query parameters are inadequately sanitized and validated. The template includes payloads designed for fuzzing and injection to identify potential vulnerabilities within the implementation. Accurate detection of this vulnerability can aid in remediating the weak configuration by restricting allowed sources and validating input more rigorously.

Exploitation can result in unauthorized access to confidential information, impersonation of users, and manipulation of website content, impacting both users and website owners. Users may unwittingly disclose sensitive credentials such as login tokens, making them susceptible to further attacks or financial fraud. Affected companies can suffer reputational damage, operational disruptions, and financial losses resulting from breached systems and leaked user data. Such vulnerabilities highlight potential weaknesses in security practices and the need for thorough auditing and rectification. Implementing strict CSP and comprehensive security measures can mitigate such risks and prevent malicious exploitation. Continuous monitoring and adaptation of security protocols are crucial in addressing evolving threats and securing web applications effectively.

REFERENCES

• https://github.com/renniepak/CSPBypass/blob/main/data.tsv