CVE-2015-5854 in Mac OS X
Summary
by MITRE
The backup implementation in Time Machine in Apple OS X before 10.11 allows local users to obtain access to keychain items via unspecified vectors.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2015-5854 resides within the backup implementation of Time Machine functionality in Apple macOS operating systems prior to version 10.11. This flaw represents a significant security oversight that undermines the integrity of the system's credential management mechanisms. The issue manifests specifically within the backup process where Time Machine creates snapshots of the user's system, including sensitive data stored in the macOS keychain. The vulnerability allows local attackers to exploit unspecified vectors that bypass normal access controls, potentially enabling unauthorized retrieval of encrypted credentials and sensitive information stored within the keychain database.
The technical nature of this vulnerability falls under the category of improper access control and privilege escalation, with direct implications for the confidentiality and integrity of user credentials. According to CWE classification, this vulnerability corresponds to CWE-284 Access Control issues, specifically involving insufficient access control mechanisms during backup operations. The flaw exploits the trust model inherent in the backup system where Time Machine's snapshot creation process does not adequately validate access permissions for keychain data, allowing local users to extract sensitive information through compromised backup mechanisms. The unspecified vectors suggest that the vulnerability may be related to improper file system permissions, inadequate encryption handling during backup creation, or flawed privilege separation between the backup process and keychain access components.
The operational impact of CVE-2015-5854 extends beyond simple credential theft to potentially compromise the entire security posture of affected systems. Local users who can leverage this vulnerability gain access to stored passwords, encryption keys, certificates, and other sensitive authentication materials that would normally be protected by the keychain's access controls. This represents a critical escalation from standard local privilege escalation to credential compromise, as the attacker can access data that should remain protected even when the system is running under normal user privileges. The vulnerability affects all macOS versions prior to 10.11, making it particularly dangerous as it encompasses a wide range of system versions that were widely deployed in enterprise and consumer environments. The threat model aligns with ATT&CK technique T1552.001 Access Tokens, as the vulnerability enables unauthorized access to credential material that would typically require elevated privileges or specific authentication mechanisms to obtain.
Mitigation strategies for this vulnerability require immediate system updates to macOS 10.11 or later versions where Apple has addressed the backup implementation flaws. System administrators should conduct comprehensive vulnerability assessments to identify affected systems and ensure all endpoints are updated to patched versions. Additionally, organizations should implement monitoring for unusual backup activities or access patterns that might indicate exploitation attempts. The remediation process should include verification that Time Machine backups are properly configured with appropriate access controls and that sensitive data is not inadvertently exposed through backup operations. Security teams should also consider implementing additional controls such as encrypted backup storage and regular audits of backup systems to prevent unauthorized access to credential material. The vulnerability highlights the importance of proper access control implementation in system-level processes and demonstrates the critical need for thorough security testing of backup and restore functionality.