CVE-2014-9036 in WordPress
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in WordPress before 3.7.5, 3.8.x before 3.8.5, 3.9.x before 3.9.3, and 4.x before 4.0.1 allows remote attackers to inject arbitrary web script or HTML via a crafted Cascading Style Sheets (CSS) token sequence in a post.
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Analysis
by VulDB Data Team • 03/02/2022
The vulnerability identified as CVE-2014-9036 represents a critical cross-site scripting flaw affecting multiple versions of the WordPress content management system. This vulnerability specifically targets the CSS parsing functionality within WordPress, creating a pathway for remote attackers to execute malicious scripts in the context of a victim's browser. The flaw exists in WordPress versions prior to 3.7.5, 3.8.x prior to 3.8.5, 3.9.x prior to 3.9.3, and 4.x prior to 4.0.1, making it a widespread concern affecting a significant portion of the WordPress ecosystem during that period. The vulnerability stems from insufficient input validation and sanitization of CSS content within WordPress posts, particularly when processing CSS token sequences that contain malicious code.
The technical nature of this vulnerability involves the improper handling of CSS content during the rendering process of WordPress posts. When users create or edit posts containing specially crafted CSS sequences, the WordPress parser fails to adequately sanitize these inputs before displaying them to end users. This allows attackers to embed malicious JavaScript code or HTML within CSS tokens, which then executes when other users view the affected posts. The vulnerability specifically leverages the way WordPress processes CSS within its post rendering pipeline, where CSS properties and values are not sufficiently escaped or validated before being rendered in the browser context. This creates a classic XSS attack vector where the malicious payload is executed in the victim's browser session, potentially leading to session hijacking, data theft, or further exploitation.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the ability to compromise user sessions and execute arbitrary commands within the context of legitimate WordPress users. Attackers can craft malicious posts containing CSS-based payloads that, when viewed by other users, can steal cookies, redirect users to malicious sites, or perform actions on behalf of the victim. The vulnerability is particularly dangerous because it can be exploited through content that appears legitimate to users, making it difficult to detect and prevent. Given that WordPress powers a significant portion of websites globally, this vulnerability could potentially affect thousands of sites, creating a substantial attack surface for malicious actors. The attack requires no special privileges or authentication, as it operates entirely through the public-facing post creation and viewing functionality of WordPress.
Mitigation strategies for CVE-2014-9036 primarily focus on immediate version upgrades to patched WordPress releases, with administrators urged to update to versions 3.7.5, 3.8.5, 3.9.3, or 4.0.1 respectively. Additionally, implementing proper input validation and sanitization measures can provide temporary protection, though this approach is less reliable than upgrading. Security headers such as Content Security Policy can offer additional protection by limiting script execution capabilities in browsers. Organizations should also consider implementing web application firewalls to detect and block suspicious CSS content patterns. This vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and maps to ATT&CK technique T1566 for initial access through malicious content. The remediation process requires comprehensive testing of the updated WordPress installation to ensure compatibility and functionality, while also implementing monitoring to detect any exploitation attempts. Regular security audits and patch management processes should be established to prevent similar vulnerabilities from occurring in the future.