CVE-2021-34637 in Post Index Plugin
Summary
by MITRE • 08/03/2021
The Post Index WordPress plugin is vulnerable to Cross-Site Request Forgery via the OptionsPage function found in the ~/php/settings.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 0.7.5.
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Analysis
by VulDB Data Team • 08/06/2021
The Post Index WordPress plugin version 0.7.5 and earlier contains a critical cross-site request forgery vulnerability that stems from inadequate input validation and missing security tokens in the OptionsPage function. This vulnerability exists within the php/settings.php file where the plugin fails to implement proper CSRF protection mechanisms, making it susceptible to malicious exploitation by attackers who can manipulate the plugin's administrative functions. The flaw allows unauthorized individuals to execute arbitrary web scripts through forged requests that appear to originate from legitimate administrators, creating a significant security risk for WordPress installations using this plugin.
The technical implementation of this vulnerability demonstrates a classic CSRF weakness where the plugin's settings page does not validate the presence of a valid nonce token or other anti-CSRF measures before processing administrative requests. Attackers can craft malicious requests that exploit the plugin's OptionsPage function to modify plugin settings, inject malicious scripts, or potentially escalate privileges within the WordPress environment. This vulnerability directly maps to CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses in web applications, and aligns with ATT&CK technique T1213.002 for Credential Access through manipulation of web application inputs.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with a potential foothold for more sophisticated attacks within the WordPress ecosystem. An attacker who successfully exploits this CSRF vulnerability could modify plugin configurations, potentially redirecting users to malicious sites, injecting persistent XSS payloads, or altering the plugin's behavior to serve as a backdoor. The vulnerability affects all WordPress installations using the affected plugin version, making it particularly dangerous as it requires minimal technical expertise to exploit and can be automated through various attack vectors. This weakness significantly undermines the security posture of affected systems and could lead to complete compromise if combined with other vulnerabilities.
Mitigation strategies should prioritize immediate plugin updates to version 0.7.6 or later where the CSRF protection has been implemented. System administrators should also consider implementing additional security measures such as web application firewalls that can detect and block suspicious request patterns, enforcing strict content security policies to prevent script execution, and monitoring for unauthorized administrative changes. The WordPress security community should also consider implementing automated scanning tools that can identify vulnerable plugins and alert administrators to potential risks. Organizations using this plugin should conduct comprehensive security assessments of their WordPress installations and ensure that all plugins are regularly updated to address known vulnerabilities, as this particular flaw represents a preventable security risk that could have been mitigated through proper implementation of CSRF protection mechanisms.