Source: cve@mitre.org
Cross-site scripting (XSS) vulnerability in feedlist/handler_image.php in the FeedList plugin 2.61.01 for WordPress allows remote attackers to inject arbitrary web script or HTML via the i parameter.
FeedList plugin 2.61.01 for WordPress is vulnerable to a cross-site scripting (XSS) attack, allowing attackers to inject malicious code into web pages viewed by users. This vulnerability, exploitable via the i parameter in feedlist/handler_image.php, could lead to account compromise, data theft, or website defacement.
Step 1: Payload Delivery: An attacker crafts a malicious URL containing JavaScript code within the i parameter of the feedlist/handler_image.php script. For example: http://vulnerable-site.com/wp-content/plugins/feedlist/feedlist/handler_image.php?i=<script>alert('XSS')</script>.
Step 2: User Interaction: A user, either directly or indirectly (e.g., through a link on a compromised site or a phishing email), visits the malicious URL.
Step 3: Code Execution: The vulnerable handler_image.php script processes the URL, including the attacker-supplied JavaScript code in the i parameter. Because the input is not sanitized, the injected JavaScript is included in the HTML response.
Step 4: Browser Rendering: The user's web browser renders the HTML response, executing the injected JavaScript code. This could include displaying an alert box (as in the example), stealing cookies, or redirecting the user to a malicious website.
The vulnerability stems from insufficient input validation and output encoding within the feedlist/handler_image.php script. Specifically, the script fails to properly sanitize the i parameter, which is used to dynamically generate image URLs. This allows an attacker to inject arbitrary HTML or JavaScript code into the parameter. When a user views a page containing the crafted URL, the injected code is executed within the context of the user's browser, enabling the attacker to perform actions on behalf of the user, such as stealing cookies, redirecting to phishing sites, or defacing the website. The root cause is a lack of input validation and output encoding (e.g., HTML entity encoding) for the i parameter before it is used to construct the image URL.
While no specific APTs are directly linked to this CVE, the ease of exploitation makes it attractive to a wide range of attackers, including script kiddies and opportunistic attackers. This vulnerability could be used as part of a larger attack chain. Not listed on CISA KEV.
Web server logs: Examine web server access logs for suspicious requests to feedlist/handler_image.php containing potentially malicious JavaScript or HTML in the i parameter. Look for patterns like <script>, onerror, javascript:, or HTML tags.
Intrusion Detection Systems (IDS): Implement IDS rules to detect XSS attempts, specifically targeting the feedlist/handler_image.php script and the i parameter. These rules should look for common XSS payloads.
Web Application Firewalls (WAF): Deploy a WAF to filter malicious requests before they reach the web server. Configure the WAF to block XSS payloads in the i parameter.
File Integrity Monitoring (FIM): Monitor the feedlist/handler_image.php file for unauthorized modifications.
Network Traffic Analysis: Analyze network traffic for unusual HTTP requests to the vulnerable endpoint.
Upgrade to a patched version of the FeedList plugin, if one exists. (Likely not possible, as the plugin is old.)
If upgrading is not possible, remove the FeedList plugin entirely. This is the most effective way to eliminate the vulnerability.
Implement a Web Application Firewall (WAF) to filter malicious requests. Configure the WAF to specifically block XSS attempts targeting the feedlist/handler_image.php script and the i parameter.
Implement Content Security Policy (CSP) to restrict the sources from which the browser can load resources, mitigating the impact of XSS attacks.
Thoroughly review and sanitize all user-supplied input before using it in dynamic content generation. This includes HTML entity encoding and other output encoding techniques.
Regularly scan the website for vulnerabilities using automated tools.
Implement a robust backup and recovery strategy to restore the website in case of a successful attack.