CVE-2010-4880 in ApPHP Calendar
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in calendar.class.php in ApPHP Calendar (ApPHP CAL) allow remote attackers to inject arbitrary web script or HTML via the (1) category_name, (2) category_description, (3) event_name, or (4) event_description parameter.
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Analysis
by VulDB Data Team • 01/22/2018
The vulnerability identified as CVE-2010-4880 affects ApPHP Calendar version 2.0.1 and represents a critical cross-site scripting flaw in the calendar.class.php file. This vulnerability resides within the web application's input validation mechanisms, specifically targeting four distinct parameters that handle user-supplied data for calendar categories and events. The flaw allows remote attackers to execute malicious scripts in the context of other users' browsers, potentially compromising the entire user session and enabling unauthorized access to sensitive information.
The technical implementation of this vulnerability stems from inadequate sanitization of user inputs within the calendar management system. When users create or modify calendar categories and events, the application fails to properly escape or filter special characters in the category_name, category_description, event_name, and event_description parameters. This lack of input validation creates an opportunity for attackers to inject malicious HTML or JavaScript code that gets stored and subsequently executed when other users view the affected calendar entries. The vulnerability operates under CWE-79 which specifically addresses cross-site scripting flaws in web applications, making it a classic example of improper output encoding or filtering.
From an operational perspective, this vulnerability poses significant risks to organizations using ApPHP Calendar for scheduling and event management. An attacker who successfully exploits this vulnerability can execute arbitrary scripts in users' browsers, potentially leading to session hijacking, credential theft, or redirection to malicious websites. The impact extends beyond simple script execution as it can enable more sophisticated attacks such as defacement of calendar content, data exfiltration, or establishment of backdoors within the application environment. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the system.
The attack surface for this vulnerability is particularly concerning as it affects core calendar functionality that users frequently interact with, making successful exploitation more likely. The vulnerability aligns with ATT&CK technique T1566.001 which covers "Phishing: Spearphishing Attachment" and T1566.002 which addresses "Phishing: Spearphishing Link," as attackers could craft malicious calendar entries designed to trigger exploitation when unsuspecting users view them. Organizations should immediately implement input validation and output encoding measures, including proper HTML escaping of all user-supplied data before storage and display. The recommended mitigation strategy includes upgrading to a patched version of ApPHP Calendar, implementing comprehensive input sanitization, and conducting regular security assessments to identify similar vulnerabilities in other components of the application stack.