CVE-2017-13819 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.1 is affected. The issue involves the "HelpViewer" component. A cross-site scripting (XSS) vulnerability allows remote attackers to inject arbitrary web script or HTML by bypassing the Same Origin Policy for quarantined HTML documents.
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Analysis
by VulDB Data Team • 09/04/2024
The vulnerability identified as CVE-2017-13819 represents a critical cross-site scripting flaw within Apple's HelpViewer component affecting macOS versions prior to 10.13.1. This security weakness resides in the operating system's handling of quarantined HTML documents, creating a pathway for malicious actors to execute arbitrary web scripts and HTML content. The issue specifically targets the Same Origin Policy implementation within the HelpViewer framework, which is designed to prevent unauthorized access between different web origins but fails to adequately protect against crafted malicious content.
The technical exploitation of this vulnerability occurs through the manipulation of quarantined HTML documents that are typically processed by the HelpViewer component. When users encounter specially crafted HTML content within the help system, the flawed Same Origin Policy implementation allows attackers to bypass normal security boundaries and inject malicious scripts that execute within the context of the HelpViewer application. This creates a persistent threat vector where remote attackers can deliver malicious payloads without requiring local user interaction beyond viewing the compromised help content. The vulnerability falls under CWE-79 which specifically addresses Cross-Site Scripting flaws, and represents a significant deviation from standard web security practices where quarantined content should be properly sanitized and isolated from executing code.
The operational impact of CVE-2017-13819 extends beyond simple script injection, as it provides attackers with a potential foothold for more sophisticated attacks within the macOS environment. Since HelpViewer is integrated into the core operating system and frequently accessed by users, the attack surface is substantial and the exploitation can occur through various vectors including malicious help documents, compromised websites, or even phishing attacks that direct users to view malicious content. The vulnerability enables attackers to potentially access user data, perform actions on behalf of the user, and establish persistent access points within the system. This aligns with ATT&CK technique T1059 which covers execution through scripting languages and command and control communications.
Mitigation strategies for this vulnerability primarily focus on immediate system updates to macOS 10.13.1 or later versions where Apple has implemented proper Same Origin Policy enforcement and HTML sanitization within the HelpViewer component. Organizations should also implement network-level controls to monitor and restrict access to potentially malicious content, particularly within help and documentation systems. Security administrators should conduct comprehensive vulnerability assessments to identify any custom help content or documentation systems that might be susceptible to similar issues, as the flaw could potentially be replicated in other components that handle quarantined HTML content. Additionally, user education regarding the dangers of viewing untrusted help content and implementing strict access controls for help system modifications can provide additional defense layers against exploitation attempts.