CVE-2011-0159 in iOS
Summary
by MITRE
The Safari Settings feature in Safari in Apple iOS 4.x before 4.3 does not properly implement the clearing of cookies during execution of the Safari application, which might make it easier for remote web servers to track users by setting a cookie.
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Analysis
by VulDB Data Team • 06/16/2017
The vulnerability identified as CVE-2011-0159 represents a significant privacy and security flaw within Apple iOS 4.x Safari implementation that persisted through versions prior to 4.3. This issue specifically targets the Safari Settings feature's handling of cookie management during application execution, creating a persistent tracking mechanism that undermines user privacy expectations. The flaw manifests when Safari fails to properly clear cookies as intended, allowing remote web servers to maintain user identification across browsing sessions despite apparent privacy controls.
This technical weakness stems from improper cookie clearing mechanisms within Safari's application architecture, where the browser does not adequately distinguish between session cookies and persistent tracking cookies during the clearing process. The vulnerability operates at the application layer, specifically affecting how Safari manages its cookie jar during runtime operations, particularly when transitioning between different browsing sessions or when users believe they have cleared their browsing data. The flaw is classified under CWE-200, which encompasses information exposure through improper handling of sensitive data, and aligns with CWE-312, concerning the exposure of sensitive information through partial clearing of data structures.
The operational impact of this vulnerability extends beyond simple privacy concerns to potentially enable sophisticated tracking and profiling activities by malicious actors. Remote web servers can exploit this weakness to maintain persistent identification of users across multiple visits, creating detailed behavioral profiles that could be used for targeted advertising, behavioral analysis, or even more nefarious purposes. This tracking capability undermines the fundamental privacy protections that users expect when they believe they have cleared their browsing history and cookies, effectively bypassing the intended privacy controls of the operating system.
Security researchers have documented that this vulnerability creates a persistent tracking vector that can be exploited across multiple domains and applications within the Safari browser environment. The flaw particularly affects users who rely on Safari's privacy features for protection against web tracking, as the browser's failure to properly clear cookies during execution negates these security measures. This vulnerability demonstrates a critical gap in Apple's implementation of privacy controls within iOS 4.x, where the intended functionality of cookie clearing does not align with the actual behavior of the application. The attack surface for this vulnerability includes any web server that implements tracking cookies, making it particularly concerning for users who browse the internet regularly and are exposed to numerous tracking mechanisms.
Organizations and users should implement immediate mitigations including updating to iOS 4.3 or later versions where this vulnerability has been addressed, implementing additional privacy protection measures such as cookie blocking extensions, and regularly reviewing browser privacy settings. Security professionals should consider this vulnerability when assessing mobile device security configurations and recommend comprehensive privacy management practices. The remediation process involves ensuring that all Safari-related components are updated to versions that properly implement cookie clearing functionality, with particular attention to verifying that the clearing process operates correctly across all browsing contexts and session types. This vulnerability serves as a reminder of the critical importance of proper cookie management and session handling in maintaining user privacy in web browsers.