CVE-2017-13872 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS High Sierra before Security Update 2017-001 is affected. The issue involves the "Directory Utility" component. It allows attackers to obtain administrator access without a password via certain interactions involving entry of the root user name.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability identified as CVE-2017-13872 represents a critical authentication bypass flaw within Apple's macOS High Sierra operating system prior to Security Update 2017-001. This issue specifically targets the Directory Utility component, which serves as a core system service responsible for managing directory services and user authentication within the macOS environment. The flaw manifests when certain interactions occur during the authentication process, particularly when the root user account is involved, creating an unintended pathway for unauthorized access to administrative privileges. The vulnerability stems from improper validation of user credentials during directory service operations, allowing attackers to bypass standard authentication mechanisms through crafted interactions with the system's authentication framework.
The technical exploitation of this vulnerability occurs through a specific sequence of operations involving the Directory Utility service and root user account handling. When a user attempts to authenticate through certain directory service interfaces, the system fails to properly validate the authentication request for the root account, enabling an attacker to gain administrative access without providing the required password. This flaw operates at the kernel level within the authentication subsystem, leveraging weaknesses in how the system processes directory service authentication requests for privileged accounts. The vulnerability specifically affects macOS High Sierra versions before the mentioned security update, where the underlying code that validates root user authentication contains a logic error that can be exploited through carefully constructed user interactions.
The operational impact of CVE-2017-13872 extends beyond simple privilege escalation to represent a fundamental compromise of system security integrity. An attacker who successfully exploits this vulnerability gains full administrative access to the affected system, enabling them to modify system configurations, install malicious software, access sensitive data, and potentially establish persistent backdoors. The vulnerability's severity is amplified by its ease of exploitation, as it requires no specialized tools or complex attack vectors beyond understanding the specific interaction patterns within the Directory Utility service. This authentication bypass effectively undermines the core security model of macOS, as it allows unauthorized users to assume administrative roles without proper credential verification, potentially affecting multiple systems within an organization if the vulnerability remains unpatched.
Mitigation strategies for this vulnerability center exclusively on applying the official Apple Security Update 2017-001, which addresses the underlying authentication validation flaw within Directory Utility. Organizations should implement comprehensive patch management processes to ensure all macOS systems receive the update promptly, as the vulnerability represents a critical security risk that could be exploited by both external attackers and insider threats. Additional defensive measures include monitoring system logs for unusual authentication patterns, implementing network segmentation to limit access to critical systems, and conducting regular security assessments to identify potentially affected systems. From a compliance perspective, this vulnerability aligns with CWE-287, which addresses improper authentication issues, and maps to ATT&CK technique T1078 for valid accounts and privilege escalation. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and highlights the potential for seemingly minor authentication flaws to create significant security breaches in enterprise environments.