CVE-2021-36387 in Yellowfin
Summary
by MITRE • 10/14/2021
In Yellowfin before 9.6.1 there is a Stored Cross-Site Scripting vulnerability in the video embed functionality exploitable through a specially crafted HTTP POST request to the page "ActivityStreamAjax.i4".
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Analysis
by VulDB Data Team • 10/20/2021
The vulnerability CVE-2021-36387 represents a critical stored cross-site scripting flaw within the Yellowfin business intelligence platform affecting versions prior to 9.6.1. This vulnerability specifically targets the video embed functionality and can be exploited through a carefully crafted HTTP POST request directed at the ActivityStreamAjax.i4 page endpoint. The issue stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before it is stored and subsequently rendered in web pages. The flaw allows attackers to inject malicious scripts that persist in the application's database and execute whenever affected pages are accessed by other users, creating a significant vector for persistent malicious activity.
The technical exploitation of this vulnerability follows a pattern consistent with stored XSS attacks as classified under CWE-79, which describes improper neutralization of input during web page generation. Attackers can leverage this weakness by submitting malicious payloads through the ActivityStreamAjax.i4 endpoint, which processes video embedding requests. The vulnerability operates at the application layer where user input intended for video URL parameters or related metadata fields is not adequately sanitized before storage. When other users access pages containing the maliciously embedded video content, their browsers execute the injected scripts within the context of the vulnerable application, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of CVE-2021-36387 extends beyond simple script execution as it represents a persistent threat that can compromise multiple users over time. This vulnerability aligns with ATT&CK technique T1566.001 for initial access through malicious content and can facilitate further attacks such as credential harvesting through browser-based attacks. The stored nature of the vulnerability means that successful exploitation can affect numerous users without requiring repeated attacks, making it particularly dangerous for collaborative environments like business intelligence platforms where multiple stakeholders access shared dashboards and activity streams. Organizations using Yellowfin versions prior to 9.6.1 face significant risk of unauthorized access and data compromise through this persistent XSS vector.
Mitigation strategies for CVE-2021-36387 primarily involve upgrading to Yellowfin version 9.6.1 or later, which includes proper input validation and output encoding fixes for the affected functionality. Organizations should also implement additional defensive measures such as input sanitization at multiple layers, regular security testing of web applications, and monitoring for suspicious activity in the ActivityStreamAjax.i4 endpoint. The vulnerability demonstrates the importance of proper content security policies and input validation as outlined in OWASP Top 10 A03:2021 and A05:2021, where inadequate data validation leads to cross-site scripting vulnerabilities. Security teams should also consider implementing web application firewalls and regular penetration testing to identify similar stored XSS vulnerabilities in other components of their business intelligence infrastructure.