CVE-2018-3773 in metascrape Module
Summary
by MITRE
There is a stored Cross-Site Scripting vulnerability in Open Graph meta properties read by the `metascrape` npm module <= 3.9.2.
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Analysis
by VulDB Data Team • 03/11/2020
The vulnerability CVE-2018-3773 represents a critical stored cross-site scripting flaw within the metascrape npm module version 3.9.2 and earlier. This vulnerability arises from the module's improper handling of Open Graph meta properties when scraping web content, creating an avenue for malicious actors to inject persistent script code into affected applications. The issue stems from the module's failure to adequately sanitize user-supplied data from Open Graph tags, which are commonly used by web applications to define rich content previews when URLs are shared on social media platforms. When applications utilizing metascrape process and store these meta properties without proper input validation, the malicious scripts become permanently embedded within the application's data store, making them persistent across user sessions and potentially affecting multiple users.
The technical exploitation of this vulnerability occurs through the manipulation of Open Graph meta tags in web pages that are being scraped by the metascrape module. Attackers can craft malicious HTML content containing script tags or other XSS payloads within Open Graph properties such as og:title, og:description, or og:image. When the vulnerable module processes these properties, it fails to implement proper output encoding or sanitization mechanisms, allowing the malicious code to be stored and subsequently executed when the scraped content is rendered in web browsers. This stored XSS vulnerability operates at the application layer and can be particularly dangerous because the malicious scripts are not limited to a single request but remain persistent within the application's data storage, potentially affecting all users who encounter the compromised content.
The operational impact of CVE-2018-3773 extends beyond simple data theft or defacement, as it can enable attackers to perform session hijacking, redirect users to malicious domains, or execute arbitrary code within the context of affected applications. The vulnerability affects any application that relies on the metascrape module for content scraping and storage, particularly those implementing social sharing features or content aggregation systems. The persistence of the stored scripts means that even if the original source page is patched, the malicious content remains embedded in the application's database, requiring thorough data cleanup and application restarts to fully remediate the issue. Organizations using vulnerable versions of metascrape may experience unauthorized access to user sessions, data exfiltration, or complete compromise of their content management systems, especially in environments where scraped content is displayed without proper sanitization.
Mitigation strategies for CVE-2018-3773 require immediate action to upgrade the metascrape npm module to version 3.9.3 or later, which includes proper input sanitization and output encoding mechanisms. Security teams should implement comprehensive input validation for all scraped content, particularly focusing on Open Graph meta properties and other user-supplied data. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws, and demonstrates characteristics consistent with ATT&CK technique T1566.001 related to spearphishing attachments. Organizations should also implement web application firewalls to detect and block suspicious script content, conduct thorough security audits of all third-party modules, and establish automated monitoring for malicious content in scraped data. Regular dependency updates and security scanning processes are essential to prevent similar vulnerabilities from being introduced through third-party libraries. Additionally, implementing proper output encoding when displaying scraped content and maintaining detailed logs of all scraping activities can help detect and respond to exploitation attempts. The vulnerability serves as a critical reminder of the importance of input validation in web applications and the potential consequences of insufficient sanitization of user-supplied content in content scraping and aggregation systems.