CVE-2011-3254 in iOS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Calendar in Apple iOS before 5 allows remote attackers to inject arbitrary web script or HTML via an invitation note.
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Analysis
by VulDB Data Team • 11/24/2021
The vulnerability identified as CVE-2011-3254 represents a critical cross-site scripting flaw within the Calendar application of Apple iOS versions prior to 5.0. This security weakness resides in the improper validation and sanitization of user input within the invitation note field, creating an exploitable condition that enables remote attackers to execute malicious web scripts or HTML code within the context of a victim's browser session. The vulnerability specifically affects the calendar invitation functionality where users receive and view calendar event invitations containing potentially malicious content.
The technical implementation of this flaw stems from inadequate input validation mechanisms within the iOS Calendar application's processing of invitation notes. When a user receives a calendar invitation containing specially crafted malicious content in the note field, the application fails to properly sanitize or escape the input before rendering it within the web interface. This allows attackers to inject HTML tags, javascript code, or other malicious scripts that execute in the context of the victim's browser session. The vulnerability is classified as a classic reflected XSS attack vector since the malicious payload is delivered through the invitation note and executed when the user views the calendar event.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to perform various malicious activities within the user's session context. An attacker could potentially steal session cookies, redirect users to malicious websites, deface calendar entries, or execute phishing attacks that appear legitimate to the user. The vulnerability affects all iOS devices running versions earlier than 5.0, making it particularly concerning given the widespread adoption of these older iOS versions at the time of discovery. The attack requires minimal user interaction beyond viewing the malicious calendar invitation, making it particularly dangerous in enterprise environments where calendar sharing is common.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-79: Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly escape or sanitize user input before incorporating it into web content. The attack vector maps to the ATT&CK technique T1566.001: Phishing, as the vulnerability enables attackers to craft convincing phishing campaigns through calendar invitations that appear legitimate to users. Additionally, the vulnerability demonstrates the importance of input validation and output encoding principles, which are fundamental to preventing XSS attacks according to OWASP Top Ten security practices.
Mitigation strategies for this vulnerability primarily involve upgrading to iOS version 5.0 or later, where Apple implemented proper input sanitization measures to prevent the injection of malicious content. System administrators should also consider implementing additional network-level protections such as web application firewalls that can detect and block suspicious script injection attempts. Users should exercise caution when viewing calendar invitations from unknown or untrusted sources and should be educated about the potential risks of clicking on suspicious links within calendar events. Organizations should also consider implementing calendar access controls and monitoring for unusual invitation patterns that might indicate attempted exploitation of this vulnerability.