CVE-2021-24879 in SupportCandy Plugin
Summary
by MITRE • 02/07/2022
The SupportCandy WordPress plugin before 2.2.7 does not have CSRF check in the wpsc_tickets AJAX action, nor has any sanitisation or escaping in some of the filter fields which could allow attackers to make a logged in user having access to the ticket lists dashboard set an arbitrary filter (stored in their cookies) with an XSS payload in it.
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Analysis
by VulDB Data Team • 02/11/2022
The vulnerability identified as CVE-2021-24879 affects the SupportCandy WordPress plugin version 2.2.6 and earlier, representing a critical security flaw that combines multiple exploitation vectors. This vulnerability specifically targets the wpsc_tickets AJAX action endpoint within the plugin's codebase, where the developers failed to implement proper Cross-Site Request Forgery protection mechanisms. The absence of CSRF validation creates a significant attack surface that allows malicious actors to manipulate the plugin's functionality through crafted requests. The flaw is particularly dangerous because it operates within the ticket lists dashboard where authenticated users maintain access, making it a prime target for privilege escalation attacks.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization practices within the plugin's filter handling mechanism. Attackers can exploit this weakness by crafting malicious requests that set arbitrary filter parameters in user cookies, effectively bypassing the standard security controls. These filter parameters are stored in the user's browser cookies and subsequently executed when the dashboard loads, creating a persistent cross-site scripting vulnerability. The vulnerability's exploitation pathway demonstrates poor security hygiene in data handling, as the plugin fails to properly sanitize or escape filter fields that are subsequently used in the user interface rendering process. This pattern of inadequate input sanitization directly aligns with CWE-79, which describes cross-site scripting vulnerabilities resulting from insufficient escaping of user-controllable data.
The operational impact of CVE-2021-24879 extends beyond simple XSS exploitation, as it enables attackers to manipulate the ticket management interface in potentially harmful ways. When a victim with access to the ticket lists dashboard loads the page, their browser executes the malicious XSS payload stored in their cookies, potentially leading to session hijacking, data exfiltration, or further privilege escalation. The vulnerability's effectiveness is amplified by the fact that it requires no special privileges beyond a valid user session, making it particularly dangerous in environments where multiple users have access to the support ticketing system. This weakness creates opportunities for attackers to establish persistent access to sensitive customer support data, potentially exposing confidential information about clients and their issues.
Mitigation strategies for this vulnerability should focus on immediate plugin updates to version 2.2.7 or later, which includes the necessary CSRF protection and input sanitization measures. Administrators should also implement additional security layers such as Content Security Policy headers to limit the execution of malicious scripts, and consider implementing web application firewalls to detect and block suspicious AJAX requests. The vulnerability's classification under the ATT&CK framework would place it within the credential access and persistence domains, specifically mapping to techniques involving session hijacking and malicious code execution. Regular security audits of WordPress plugins should include verification of CSRF protection mechanisms and input sanitization practices to prevent similar vulnerabilities from emerging in the future. Organizations should also consider implementing user session monitoring and alerting systems to detect unusual activities that might indicate exploitation attempts against such vulnerabilities.