CVE-2018-13849 in Instagram-clone
Summary
by MITRE
edit_requests.php in yTakkar Instagram-clone through 2018-04-23 has XSS via an onmouseover payload because of an inadequate XSS protection mechanism based on preg_replace.
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Analysis
by VulDB Data Team • 06/25/2024
The vulnerability identified as CVE-2018-13849 affects the edit_requests.php component of a yTakkar Instagram-clone application version released on or before April 23, 2018. This represents a cross-site scripting weakness that allows attackers to inject malicious JavaScript code into the application's user interface through improper input validation mechanisms. The vulnerability specifically manifests when the application processes user-supplied data containing onmouseover event handlers without adequate sanitization, creating a persistent security risk for all users interacting with the platform.
The technical flaw stems from an inadequate XSS protection mechanism that relies on preg_replace functions for input filtering. This approach demonstrates a fundamental misunderstanding of web application security principles and fails to properly sanitize user input before rendering it within the application's interface. The preg_replace function, while useful for string manipulation, does not provide comprehensive protection against XSS attacks when used in isolation without proper context-aware sanitization. The vulnerability allows attackers to inject malicious payloads that execute in the context of other users' browsers, potentially leading to session hijacking, credential theft, or further exploitation of the application's functionality.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with persistent access to user sessions and potentially sensitive application data. When users view pages containing malicious payloads, the injected JavaScript code executes automatically in their browsers, creating opportunities for attackers to steal cookies, session tokens, or perform actions on behalf of authenticated users. This vulnerability particularly affects social media applications where user-generated content is prevalent, as it enables attackers to compromise the entire user base through a single injection point. The persistence of this vulnerability means that once exploited, malicious code can affect all users until the application is properly patched and the malicious content is removed from the database.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and output encoding mechanisms that adhere to established security standards such as those defined in the CWE-79 category for Cross-Site Scripting. The application should employ context-specific output encoding before rendering any user-supplied content, utilizing libraries such as HTMLPurifier or similar security-focused components that properly handle various attack vectors. Additionally, implementing Content Security Policy headers can provide an additional layer of protection against unauthorized script execution. The security team should also conduct comprehensive code reviews to identify similar patterns throughout the application and implement proper threat modeling to prevent similar vulnerabilities in future development cycles. This vulnerability serves as a reminder of the importance of proper input validation and the dangers of relying on incomplete or overly simplistic sanitization approaches in web application security.