CVE-2015-7044 in Mac OS X
Summary
by MITRE
The System Integrity Protection feature in Apple OS X before 10.11.2 mishandles union mounts, which allows attackers to execute arbitrary code in a privileged context via a crafted app with root privileges.
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Analysis
by VulDB Data Team • 11/16/2024
The vulnerability identified as CVE-2015-7044 resides within Apple's System Integrity Protection (SIP) mechanism implemented in macOS operating systems prior to version 10.11.2. This security feature was designed to protect critical system files and directories from modification by unauthorized processes, thereby preventing malicious actors from compromising the integrity of the operating system. The flaw specifically manifests in how the system handles union mounts, which are filesystem constructs that overlay multiple directories to create a single unified view. Union mounts are commonly used in macOS for various system operations including the mounting of read-only filesystems and the creation of temporary filesystem overlays.
The technical implementation of this vulnerability stems from improper handling of union mount operations within the kernel-level filesystem management code. When a crafted application attempts to create or manipulate union mounts, the system fails to properly validate the mount operations, allowing for privilege escalation. This occurs because the SIP mechanism does not adequately enforce its restrictions when union mounts are involved, creating a path for malicious code to bypass the normal security boundaries that should prevent unauthorized modifications to protected system areas. The vulnerability essentially allows an attacker with a privileged application to manipulate the filesystem in ways that should be restricted, enabling the execution of arbitrary code with elevated privileges. This flaw directly relates to CWE-276, which describes improper privilege management, and represents a critical weakness in the access control mechanisms of the operating system.
The operational impact of CVE-2015-7044 is severe and far-reaching within the macOS ecosystem. Attackers can leverage this vulnerability to gain root-level access to systems running affected versions of macOS, effectively bypassing the core security protections that SIP was designed to provide. Once exploited, the vulnerability enables complete system compromise, allowing attackers to install persistent backdoors, modify critical system files, and establish covert communication channels. The attack vector requires only a crafted application with root privileges, which makes exploitation relatively straightforward for adversaries who have already gained some level of system access. This vulnerability particularly affects enterprise environments where macOS systems may be running outdated versions, as it provides a direct path to privilege escalation that can be used to maintain persistent access to networks. The impact extends beyond individual system compromise to potentially affect entire network infrastructures, as compromised systems can serve as launch points for further attacks against other networked devices.
Mitigation strategies for CVE-2015-7044 focus primarily on immediate system updates and operational security measures. The most effective remediation is upgrading to macOS version 10.11.2 or later, which includes the necessary patches to properly handle union mount operations within the SIP framework. Organizations should implement comprehensive patch management policies to ensure all macOS systems receive timely updates, particularly given the severity of this vulnerability. Additionally, system administrators should monitor for suspicious union mount operations and implement process monitoring to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper filesystem access control and the need for robust kernel-level validation of all mount operations. Security teams should also consider implementing additional monitoring controls that can detect unauthorized privilege escalation attempts and maintain detailed audit logs of system modifications. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and the potential consequences of running unsupported software versions in enterprise environments. The incident highlights the necessity of following ATT&CK framework principles for privilege escalation techniques, particularly those involving filesystem manipulation and kernel-level exploitation methods that bypass standard security controls.