CVE-2015-4089 in WP Fastest Cache Plugin
Summary
by MITRE
Multiple cross-site request forgery (CSRF) vulnerabilities in the optionsPageRequest function in admin.php in WP Fastest Cache plugin before 0.8.3.5 for WordPress allow remote attackers to hijack the authentication of unspecified victims for requests that call the (1) saveOption, (2) deleteCache, (3) deleteCssAndJsCache, or (4) addCacheTimeout method via the wpFastestCachePage parameter in the WpFastestCacheOptions/ page.
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Analysis
by VulDB Data Team • 11/17/2019
The CVE-2015-4089 vulnerability represents a critical cross-site request forgery flaw in the WP Fastest Cache WordPress plugin, affecting versions prior to 0.8.3.5. This vulnerability exists within the optionsPageRequest function in the admin.php file, which handles administrative operations for the caching plugin. The flaw allows remote attackers to exploit the authentication mechanism by tricking users into executing unauthorized actions on the vulnerable WordPress site, potentially leading to complete administrative compromise of the affected installation.
The technical implementation of this CSRF vulnerability stems from the lack of proper authentication verification within the optionsPageRequest function. When users navigate to the WpFastestCacheOptions/ page and interact with the wpFastestCachePage parameter, the system fails to validate that requests originate from legitimate administrative sessions. This parameter directly controls access to four critical methods: saveOption, deleteCache, deleteCssAndJsCache, and addCacheTimeout, which can be invoked without proper CSRF token validation or session verification. The vulnerability manifests because the plugin relies on the presence of a valid WordPress admin session rather than implementing robust CSRF protection mechanisms that would prevent unauthorized requests from being processed.
The operational impact of this vulnerability extends beyond simple data manipulation, as it provides attackers with the capability to execute administrative functions that could completely compromise a WordPress site. Successful exploitation could enable attackers to delete critical cache files, modify plugin configuration settings, or even add malicious cache timeouts that could persist across the site's operation. The unspecified victims mentioned in the vulnerability description indicate that any authenticated user session could be hijacked, making this particularly dangerous in environments where multiple administrators or users have access to the WordPress backend. This vulnerability directly maps to CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses in software applications.
From an attacker's perspective, this vulnerability operates through social engineering techniques where users are tricked into visiting malicious websites or clicking on compromised links that automatically submit requests to the vulnerable WordPress installation. The attacker could craft malicious pages that, when visited by an authenticated administrator, would silently perform cache deletion or configuration changes. The attack vector aligns with ATT&CK technique T1078.004, which describes legitimate credentials usage for persistence and privilege escalation. The vulnerability's impact is amplified by the fact that it affects a widely used caching plugin, meaning that successful exploitation could compromise numerous WordPress installations simultaneously.
The recommended mitigation strategy involves immediate upgrading to WP Fastest Cache version 0.8.3.5 or later, which includes proper CSRF token validation and session verification mechanisms. Additionally, administrators should implement proper input validation and output encoding practices to prevent similar vulnerabilities in other plugin components. Security monitoring should include detection of unauthorized cache modifications and configuration changes, while network-level protections such as web application firewalls can help identify and block malicious requests attempting to exploit this vulnerability. The fix implemented in version 0.8.3.5 should include proper verification of user sessions and implementation of anti-CSRF tokens for all administrative functions, following industry best practices for secure web application development and aligning with OWASP Top 10 security recommendations for preventing cross-site request forgery attacks.