CVE-2018-4329 in Safari
Summary
by MITRE
Clearing a history item may not clear visits with redirect chains. The issue was addressed with improved data deletion. This issue affected versions prior to iOS 12, Safari 12.
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Analysis
by VulDB Data Team • 08/22/2023
The vulnerability identified as CVE-2018-4329 represents a significant privacy and data retention flaw within Apple's web browsing ecosystem. This issue specifically affected iOS versions prior to iOS 12 and Safari 12, where the browser's history clearing functionality failed to properly remove all associated visit data when users attempted to delete browsing history items. The flaw stemmed from the browser's inadequate handling of redirect chains that occur during web navigation, creating a persistent data leakage vector that undermined user privacy expectations.
The technical nature of this vulnerability lies in how Safari manages its internal data structures for tracking web visits and redirects. When a user cleared their browsing history, the system was designed to remove records of visited websites, but it failed to account for the complex redirect chains that often occur during web navigation. These redirect chains consist of multiple HTTP status codes that redirect users from one URL to another, creating a series of visit records that should be cleared alongside the primary history item. The flaw allowed these redirect chain entries to persist in the database even after the main history item had been deleted, creating a hidden trail of user activity that could be reconstructed by forensic analysis or accessed through various system interfaces.
From an operational perspective, this vulnerability created a substantial risk for user privacy and data protection. The persistence of redirect chain data meant that even when users believed they had completely cleared their browsing history, traces of their web activity remained accessible. This could potentially expose sensitive information about user behavior patterns, including visits to confidential websites, personal accounts, or potentially compromising web resources. The issue was particularly concerning for users who relied on private browsing modes or regular history clearing as privacy protection measures, as the flaw effectively nullified these security practices.
The vulnerability aligns with CWE-200, which addresses "Information Exposure Through Output Redirection," and represents a failure in proper data sanitization during user-initiated deletion operations. From an ATT&CK framework perspective, this flaw could be categorized under T1070.004, "File Deletion," as it involves improper handling of data removal processes, and potentially T1566, "Phishing," since the persistent data could be exploited to reconstruct user behavior patterns that might aid social engineering attacks. The issue was addressed through improved data deletion algorithms that properly traverse and remove all associated redirect chain entries when users initiate history clearing operations, ensuring that all related visit data is properly sanitized.
Mitigation strategies for this vulnerability required users to upgrade to iOS 12 or later versions where Apple implemented corrected data deletion procedures. System administrators and security professionals should have monitored for affected systems and ensured timely deployment of security updates. Organizations relying on Safari for web browsing should have conducted risk assessments to identify potential exposure windows and implemented additional monitoring for unauthorized data access patterns. The fix demonstrated Apple's commitment to addressing privacy-related vulnerabilities through improved data handling practices and proper sanitization of user-generated content.