CVE-2021-42365 in Asgaros Forums Plugin
Summary
by MITRE • 11/29/2021
The Asgaros Forums WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient escaping via the name parameter found in the ~/admin/tables/admin-structure-table.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 1.15.13. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.
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Analysis
by VulDB Data Team • 12/02/2021
The Asgaros Forums WordPress plugin version 1.15.13 and earlier contains a critical stored cross-site scripting vulnerability that poses significant security risks to WordPress installations. This vulnerability exists within the administrative interface of the plugin, specifically in the admin-structure-table.php file where the name parameter is not properly sanitized or escaped. The flaw allows attackers with administrative privileges to inject malicious scripts that persist in the database and execute whenever the affected page is loaded by other users. The vulnerability particularly affects multi-site installations where unfiltered_html capabilities are restricted for administrators, creating an environment where even privileged users cannot bypass the sanitization mechanisms that should protect against such attacks.
The technical exploitation of this vulnerability occurs through the manipulation of the name parameter in the administrative structure table functionality. When administrators access the plugin's administrative interface, the unsanitized input is directly rendered back to users without proper HTML escaping or output encoding. This creates a persistent XSS vector where malicious scripts can be stored in the database and executed in the context of other users' browsers. The vulnerability is classified as a stored XSS due to the persistence of the malicious code in the server-side database rather than a reflected XSS where the payload is delivered through a malicious link. The flaw leverages the administrative access rights of the attacker to inject scripts that can then be executed in the browsers of other users who view the affected administrative pages, potentially enabling session hijacking, credential theft, or further exploitation of the compromised systems.
The operational impact of this vulnerability extends beyond simple script execution, as it creates opportunities for attackers to escalate privileges and compromise entire WordPress installations. When administrators with elevated permissions are targeted, the vulnerability can be used to gain persistent access to the administrative interface, allowing attackers to modify plugin settings, create new administrative users, or even install malicious plugins. The vulnerability affects installations where unfiltered_html is disabled, which represents a common security configuration in WordPress environments where administrators want to prevent the execution of potentially malicious code. However, the flaw demonstrates how even restricted environments can be compromised when plugins fail to properly validate and sanitize user inputs. The attack surface is particularly concerning in multi-site installations where administrators may have varying levels of access control and where the complexity of the security model can create unexpected vulnerabilities.
Organizations should implement immediate mitigations including updating to the patched version of the Asgaros Forums plugin, which addresses the insufficient escaping of the name parameter. Security administrators should also consider implementing additional protective measures such as restricting administrative access to trusted users only, implementing web application firewalls to detect and block malicious script injection attempts, and monitoring administrative interfaces for suspicious activity. The vulnerability aligns with CWE-79 which describes Cross-Site Scripting flaws, and may map to ATT&CK technique T1566.001 which covers social engineering through spearphishing. Organizations should also consider implementing Content Security Policy headers to limit the execution of unauthorized scripts, and conduct regular security audits of WordPress plugins to identify similar vulnerabilities that may exist in other third-party components. Proper input validation and output encoding should be enforced throughout the application to prevent similar issues from occurring in other areas of the codebase.