CVE-2021-24312 in WP Super Cache Plugin
Summary
by MITRE • 06/02/2021
The parameters $cache_path, $wp_cache_debug_ip, $wp_super_cache_front_page_text, $cache_scheduled_time, $cached_direct_pages used in the settings of WP Super Cache WordPress plugin before 1.7.3 result in RCE because they allow input of '$' and '\n'. This is due to an incomplete fix of CVE-2021-24209.
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Analysis
by VulDB Data Team • 06/03/2021
The vulnerability identified as CVE-2021-24312 affects the WP Super Cache WordPress plugin version prior to 1.7.3, representing a critical remote code execution risk that stems from insufficient input validation in multiple plugin parameters. This issue arises from the improper handling of user-supplied data within the plugin's configuration settings, specifically targeting variables including $cache_path, $wp_cache_debug_ip, $wp_super_cache_front_page_text, $cache_scheduled_time, and $cached_direct_pages. The vulnerability represents a regression in security measures that were initially addressed in CVE-2021-24209, demonstrating the importance of comprehensive vulnerability remediation and the potential for incomplete fixes to create new attack vectors.
The technical flaw manifests through the plugin's failure to properly sanitize or escape input values before processing them within the WordPress environment. When these parameters contain special characters such as the dollar sign '$' and newline characters '\n', the plugin's code execution logic can be manipulated to inject and execute arbitrary PHP code. This occurs because the plugin's configuration handling does not adequately filter or escape these characters, allowing attackers to craft malicious inputs that bypass normal security controls. The vulnerability specifically leverages the fact that these parameters are processed in contexts where PHP code evaluation might occur, creating opportunities for attackers to execute arbitrary commands on the affected server.
The operational impact of CVE-2021-24312 is severe and far-reaching, as it provides attackers with complete remote code execution capabilities on compromised WordPress installations. Successful exploitation allows adversaries to execute arbitrary code with the privileges of the web server, potentially enabling them to establish persistent backdoors, exfiltrate sensitive data, modify website content, or use the compromised server as a launching point for further attacks within the network. The vulnerability affects not only the targeted WordPress site but also creates potential risks for the entire hosting environment, as attackers can leverage the compromised system to conduct additional malicious activities. This type of vulnerability directly violates the principle of least privilege and can lead to complete system compromise, making it a critical concern for website administrators and security professionals.
Mitigation strategies for CVE-2021-24312 should prioritize immediate plugin updates to version 1.7.3 or later, which contains the necessary security patches addressing the input validation deficiencies. Organizations should also implement network-level protections such as web application firewalls that can detect and block malicious input patterns targeting these specific parameters. Additional defensive measures include restricting administrative access to the WordPress dashboard, implementing proper input validation at multiple layers of the application architecture, and conducting regular security audits of plugin configurations. The vulnerability aligns with CWE-74 and CWE-94 categories related to injection flaws and code execution vulnerabilities, and represents a technique commonly associated with ATT&CK tactic TA0001 (Initial Access) and technique T1059.001 (Command and Scripting Interpreter) in adversarial attack frameworks. System administrators should also consider implementing monitoring solutions that can detect unusual code execution patterns and unauthorized configuration changes, as these indicators may suggest exploitation attempts.