CVE-2015-9270 in the-holiday-calendar Plugin
Summary
by MITRE
XSS exists in the the-holiday-calendar plugin before 1.11.3 for WordPress via the thc-month parameter.
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Analysis
by VulDB Data Team • 03/28/2020
The vulnerability identified as CVE-2015-9270 represents a cross-site scripting flaw within the the-holiday-calendar WordPress plugin, affecting versions prior to 1.11.3. This issue arises from inadequate input validation and output escaping mechanisms within the plugin's handling of user-supplied data. The vulnerability specifically manifests through the thc-month parameter, which is processed without proper sanitization, creating an avenue for malicious actors to inject arbitrary JavaScript code into the web application's response. The flaw resides in the plugin's failure to properly encode or filter user input before incorporating it into dynamic web content, thereby enabling attackers to execute malicious scripts in the context of other users' browsers.
The technical implementation of this vulnerability follows the standard XSS attack pattern where the thc-month parameter serves as the injection vector for malicious payloads. When the plugin processes this parameter, it fails to apply appropriate HTML escaping or context-specific encoding mechanisms, allowing attackers to inject script tags or other malicious code that gets executed when legitimate users view the affected pages. This vulnerability falls under CWE-79 which categorizes improper neutralization of input during web page generation, specifically targeting the web application's output generation process. The attack chain typically involves an attacker crafting a malicious URL containing script code within the thc-month parameter and then persuading a victim to click on the crafted link, leading to script execution in the victim's browser context.
The operational impact of CVE-2015-9270 extends beyond simple script execution as it enables attackers to perform various malicious activities within the compromised user sessions. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious sites, deface the calendar displays, or even execute more sophisticated attacks such as credential harvesting or privilege escalation within the WordPress environment. The vulnerability affects the integrity and availability of the calendar plugin's functionality, potentially leading to unauthorized modifications of holiday data or complete compromise of user sessions. From an attacker's perspective, this vulnerability represents a low-hanging fruit that can be exploited without requiring elevated privileges or complex attack chains, making it particularly dangerous in environments where WordPress plugins are widely used and may not be regularly updated.
Mitigation strategies for CVE-2015-9270 primarily focus on immediate patching of the affected plugin to version 1.11.3 or later, which includes proper input validation and output escaping mechanisms. Organizations should implement comprehensive plugin management policies that include regular updates, security scanning, and monitoring for vulnerable components within their WordPress installations. The vulnerability demonstrates the importance of input validation and output encoding practices, aligning with ATT&CK technique T1566 which covers the use of malicious web content and T1213 which involves data from information repositories. Additionally, implementing web application firewalls with XSS detection capabilities and enforcing Content Security Policy headers can provide additional layers of defense. Security teams should also conduct regular vulnerability assessments of WordPress plugins and ensure that all third-party components are maintained with the latest security patches to prevent exploitation of similar vulnerabilities in other plugins or components within the web application ecosystem.