CVE-2018-17583 in WP Fastest Cache Plugin
Summary
by MITRE
The WP Fastest Cache plugin 0.8.8.5 for WordPress has XSS via the rules[0][content] parameter in a wpfc_save_exclude_pages action.
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Analysis
by VulDB Data Team • 08/29/2023
The WP Fastest Cache plugin version 0.8.8.5 for WordPress contains a cross-site scripting vulnerability that allows attackers to inject malicious scripts into the application's web interface. This vulnerability specifically affects the wpfc_save_exclude_pages action handler where the rules[0][content] parameter is processed without adequate input validation or output sanitization. The flaw exists in the plugin's handling of user-supplied data within the cache exclusion rules configuration, creating an opportunity for malicious actors to execute arbitrary JavaScript code in the context of authenticated admin sessions.
The technical implementation of this vulnerability stems from insufficient sanitization of the rules[0][content] parameter during the wpfc_save_exclude_pages action processing. When administrators configure cache exclusion rules, the plugin accepts user input directly into the content field without proper encoding or validation of potentially malicious content. This allows an attacker to inject script tags or other malicious payloads that will execute whenever the affected page is rendered or processed. The vulnerability is particularly dangerous because it targets the administrative interface of WordPress, where users have elevated privileges and access to sensitive system functions.
The operational impact of this vulnerability extends beyond simple script execution, as it can lead to complete administrative compromise of WordPress installations. An attacker who successfully exploits this XSS vulnerability can hijack administrator sessions, modify website content, install malware, or escalate privileges within the WordPress environment. The attack vector requires minimal privileges since the vulnerability exists in a function that processes administrative inputs, making it accessible to users who can access the plugin's configuration interface. This creates a significant risk for websites where multiple users have administrative access or where the plugin configuration is exposed to untrusted parties.
Security mitigations for this vulnerability should focus on input validation and output encoding at multiple layers. The plugin developers must implement proper sanitization of all user inputs, particularly those used in configuration parameters that are later rendered in web contexts. Input validation should occur at the point of data entry, ensuring that only expected content types are accepted for the rules[0][content] parameter. Output encoding must be applied when rendering any user-supplied content within HTML contexts to prevent script execution. Organizations should also implement network-level protections such as web application firewalls that can detect and block suspicious payloads targeting this specific vulnerability. Regular security audits of WordPress plugins and core systems should be conducted to identify similar input validation flaws that could lead to more severe exploitation vectors.
This vulnerability aligns with CWE-79, which describes cross-site scripting flaws in software applications, and represents a classic example of insecure input handling in web applications. From an ATT&CK perspective, this weakness maps to T1213.002 for Data from Information Repositories and T1566.001 for Phishing, as the vulnerability can be exploited through social engineering to gain initial access to administrative interfaces. The attack surface is particularly concerning in enterprise environments where WordPress installations may be exposed to external networks or where multiple users have access to plugin configuration interfaces, making this vulnerability a critical target for exploitation by threat actors seeking persistent access to web applications.