CVE-2021-20688 in Click Ranker
Summary
by MITRE • 04/07/2021
Cross-site scripting vulnerability in Click Ranker Ver.3.5 allows remote attackers to inject an arbitrary script via unspecified vectors.
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Analysis
by VulDB Data Team • 04/11/2021
The CVE-2021-20688 vulnerability represents a critical cross-site scripting flaw discovered in the Click Ranker plugin version 3.5, exposing web applications to significant security risks. This vulnerability falls under the category of client-side injection attacks that can be exploited by remote attackers without requiring authentication or privileged access. The vulnerability stems from inadequate input validation and output encoding mechanisms within the plugin's codebase, creating an avenue for malicious actors to execute arbitrary scripts in the context of a victim's browser session. The unspecified vectors indicate that the attack surface encompasses multiple potential entry points where user-supplied data is not properly sanitized before being rendered back to users.
The technical implementation of this XSS vulnerability demonstrates a classic flaw in web application security where the Click Ranker plugin fails to adequately sanitize user input before processing and displaying it on web pages. This weakness allows attackers to inject malicious JavaScript code through various input fields or parameters that the plugin handles. The vulnerability's classification aligns with CWE-79 which specifically addresses Cross-Site Scripting flaws in web applications. When exploited, the XSS vulnerability can enable attackers to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious websites, or harvest sensitive information from authenticated sessions. The impact is particularly severe because the vulnerability affects a plugin that likely handles user interactions and data processing, making it a prime target for exploitation.
The operational impact of CVE-2021-20688 extends beyond simple data theft, as it can facilitate more sophisticated attacks within the target environment. Attackers can leverage this vulnerability to establish persistent access through session hijacking, execute malicious commands on behalf of legitimate users, or deploy additional malware. The remote nature of the attack means that exploitation can occur from anywhere on the internet without requiring physical access to the target system. This vulnerability directly maps to several ATT&CK techniques including T1566.001 for initial access through malicious links and T1059.007 for command and scripting interpreter usage. Organizations running affected versions of Click Ranker face potential data breaches, unauthorized access to sensitive information, and possible compromise of user accounts, especially if the plugin is used in environments with authenticated users or handles personal identifiable information.
Mitigation strategies for CVE-2021-20688 should prioritize immediate remediation through plugin updates to versions that address the XSS vulnerability. System administrators must ensure that all instances of Click Ranker are updated to the latest secure version that implements proper input validation and output encoding mechanisms. Additionally, implementing Content Security Policy headers can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded and executed. Input validation should be strengthened to sanitize all user-supplied data before processing, while output encoding must be implemented to ensure that any potentially malicious content is rendered harmless when displayed to users. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other plugins or components of the web application ecosystem, as this vulnerability demonstrates the importance of maintaining up-to-date software and implementing robust security controls throughout the application stack.