CVE-2017-17094 in WordPress
Summary
by MITRE
wp-includes/feed.php in WordPress before 4.9.1 does not properly restrict enclosures in RSS and Atom fields, which might allow attackers to conduct XSS attacks via a crafted URL.
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Analysis
by VulDB Data Team • 01/16/2023
The vulnerability identified as CVE-2017-17094 represents a critical cross-site scripting flaw within the WordPress content management system affecting versions prior to 4.9.1. This issue resides in the wp-includes/feed.php file which handles the generation of RSS and Atom feeds that are commonly used for syndicating content across different platforms and services. The vulnerability stems from insufficient input validation and sanitization of enclosure URLs within feed generation processes, creating an avenue for malicious actors to inject arbitrary JavaScript code into feed content that can subsequently be executed by unsuspecting users who consume these feeds through various feed readers or content aggregation services.
The technical nature of this vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws where untrusted data is improperly incorporated into web pages without proper validation or sanitization. Attackers can exploit this weakness by crafting malicious URLs containing JavaScript payloads and embedding them within enclosure fields of RSS or Atom feeds. When WordPress generates these feeds, the malicious content is not properly escaped or filtered, allowing the injected scripts to execute in the context of users' browsers when they access the affected feeds through compatible readers or aggregators. This particular flaw operates at the application layer and can be classified under the ATT&CK technique T1566.001 which involves the use of malicious feeds and content to deliver attacks.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform a wide range of malicious activities including session hijacking, data exfiltration, and redirection to malicious sites. Users who consume WordPress feeds through third-party applications or browser extensions become potential victims, making this a vector that affects not just WordPress administrators but also end users who consume content through various syndication methods. The vulnerability is particularly concerning because it operates silently in the background and can be exploited through legitimate feed consumption patterns, making detection difficult for security monitoring systems.
Mitigation strategies for CVE-2017-17094 primarily involve upgrading to WordPress version 4.9.1 or later where the vulnerability has been patched through proper input validation and sanitization of enclosure URLs in feed generation. Organizations should also implement feed validation mechanisms and content filtering to prevent the ingestion of malicious feeds into their systems. Security teams should monitor feed consumption patterns and consider implementing web application firewalls that can detect and block suspicious feed content. Additionally, administrators should regularly audit their WordPress installations for outdated versions and ensure that all plugins and themes are also updated to prevent exploitation through other attack vectors that might compound the risk. The patch implemented by WordPress developers specifically addresses the improper handling of user-supplied enclosure data by ensuring that URLs are properly sanitized before inclusion in generated feeds, thereby preventing the execution of malicious scripts through this particular attack surface.