CVE-2019-6204 in Safari
Summary
by MITRE
A logic issue was addressed with improved validation. This issue is fixed in iOS 12.2, Safari 12.1. Enabling the Safari Reader feature on a maliciously crafted webpage may lead to universal cross site scripting.
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Analysis
by VulDB Data Team • 08/08/2023
The vulnerability identified as CVE-2019-6204 represents a significant security flaw in Apple's Safari browser and iOS operating system that was addressed through improved input validation mechanisms. This issue specifically affects the Safari Reader feature, which is designed to provide a cleaner reading experience by stripping away advertisements and clutter from web pages. The vulnerability stems from insufficient validation of web content when the Reader feature is enabled, creating a potential pathway for malicious actors to exploit the browser's rendering engine.
The technical flaw manifests when users navigate to a maliciously crafted webpage that has been specifically designed to trigger the Safari Reader feature. The vulnerability is classified as a logic issue under CWE-252, which deals with "Unchecked Return Value" and represents a broader category of flaws where the system fails to properly validate or sanitize inputs before processing them. When the Reader feature processes the malicious content, it fails to properly validate the HTML structure and embedded scripts, allowing for the execution of arbitrary code that can bypass normal security boundaries.
The operational impact of this vulnerability extends beyond simple cross-site scripting attacks, as it enables what is known as universal cross-site scripting. This means that attackers can potentially execute malicious scripts across all domains that the browser visits, creating a persistent threat vector that can compromise user data and session information. The vulnerability is particularly dangerous because it leverages a legitimate browser feature that users frequently employ, making social engineering attacks more effective and harder to detect. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1203 (Exploitation for Client Execution) categories, as it allows for client-side exploitation through browser-based attack vectors.
The remediation for CVE-2019-6204 was implemented through iOS 12.2 and Safari 12.1 updates, which introduced enhanced validation mechanisms for content processing within the Reader feature. These updates specifically addressed the input sanitization routines that were previously insufficient to prevent malicious content from being rendered in the reader context. Security professionals should note that this vulnerability highlights the importance of validating all user-facing content, even within seemingly benign browser features. Organizations should ensure that all systems are updated to the latest versions of Apple's operating systems and browsers to prevent exploitation of this and similar vulnerabilities that could lead to unauthorized access to sensitive information and persistent threat vectors within enterprise environments.