CVE-2016-4645 in Mac OS X
Summary
by MITRE
CFNetwork in Apple OS X before 10.11.6 uses weak permissions for web-browser cookies, which allows local users to obtain sensitive information via unspecified vectors.
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Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-4645 resides within Apple's CFNetwork framework, which serves as the core networking infrastructure for macOS operating systems. This flaw affects versions prior to macOS 10.11.6, representing a significant security weakness that undermines the integrity of web browser cookie storage mechanisms. The issue manifests through improper permission settings that govern how cookie data is stored and accessed within the system's file hierarchy.
The technical implementation of this vulnerability stems from weak file permissions applied to cookie storage locations within the CFNetwork subsystem. When web browsers and network applications store cookie data, they typically create files or database entries that contain session information, authentication tokens, and other sensitive user data. In affected macOS versions, these storage locations were configured with insufficient access controls, allowing any local user account to read cookie files that should remain protected. This permission misconfiguration creates a privilege escalation scenario where low-privilege users can access data belonging to other users or system processes.
The operational impact of this vulnerability extends beyond simple information disclosure, as cookie data often contains session identifiers, authentication tokens, and personal user information that could be leveraged for further attacks. An attacker with local access could potentially reconstruct user sessions, impersonate legitimate users, or extract sensitive authentication credentials that would otherwise remain protected. The unspecified vectors mentioned in the original description suggest that multiple attack surfaces within the network stack could be exploited, making this vulnerability particularly concerning for environments where multiple users share systems or where security boundaries are not properly maintained.
This vulnerability aligns with CWE-276, which addresses improper file permissions, and represents a classic case of inadequate access control implementation within a system's security architecture. The flaw demonstrates how seemingly minor permission settings can create significant security gaps that compromise user privacy and system integrity. From an adversary perspective, this vulnerability maps to several ATT&CK techniques including credential access through file and directory permissions modification, as well as privilege escalation by leveraging weakly protected data stores. The attack surface is particularly relevant in multi-user environments where local access is possible, making it a common target for both insider threats and attackers who have gained local system access through other means.
Mitigation strategies for CVE-2016-4645 require immediate system updates to macOS 10.11.6 or later versions where Apple has corrected the permission settings for cookie storage. System administrators should also implement additional monitoring of cookie storage locations and verify that proper file permissions are maintained across all network-related applications. Organizations should consider implementing additional security controls such as mandatory access controls, regular permission audits, and enhanced logging of file access patterns to detect potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date operating systems and underscores the critical role that proper file permission management plays in preventing unauthorized data access within networked environments.