CVE-2015-7063 in Mac OS X
Summary
by MITRE
The kernel loader in EFI in Apple OS X before 10.11.2 allows local users to gain privileges via a crafted pathname.
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Analysis
by VulDB Data Team • 06/29/2022
The vulnerability identified as CVE-2015-7063 represents a critical privilege escalation flaw within the EFI kernel loader component of Apple's macOS operating system. This issue affects versions prior to macOS 10.11.2 and stems from improper handling of crafted pathname arguments during the EFI boot process. The vulnerability resides in the way the system processes and validates file paths when loading kernel modules or firmware components through the EFI environment, creating an opportunity for local attackers to manipulate the boot sequence and execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability involves a path traversal or injection attack vector where malicious input can be passed through pathname arguments to the EFI loader. When the system processes these paths, it fails to properly sanitize or validate the input, allowing an attacker to craft specific pathname sequences that bypass normal access controls. This flaw operates at the intersection of operating system boot security and firmware integrity, leveraging the trust relationships between the EFI environment and the kernel loading process. The vulnerability aligns with CWE-22 Path Traversal and CWE-78 Command Injection categories, as it allows for manipulation of path resolution and command execution within the privileged boot environment.
The operational impact of CVE-2015-7063 is significant as it enables local users to escalate their privileges from standard user level to system administrator level without requiring additional authentication or exploitation of other vulnerabilities. Once exploited, the attacker gains the ability to modify system files, install malicious software, or establish persistent access to the compromised system. The attack requires local system access but does not necessitate network connectivity or specialized hardware, making it particularly dangerous in environments where user accounts may be compromised or where insider threats exist. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under privilege escalation tactics, specifically targeting boot and logon processes where system integrity is most critical.
The mitigation strategy for CVE-2015-7063 involves upgrading to macOS 10.11.2 or later versions where Apple has implemented proper input validation and path sanitization within the EFI kernel loader. System administrators should also implement additional security measures including monitoring for unusual file access patterns, ensuring proper system patch management, and applying the official security updates provided by Apple. The vulnerability demonstrates the importance of secure boot chain implementation and proper input validation in firmware environments, emphasizing that security controls must be robust at every layer of the system architecture from user space through kernel space to firmware level operations. Organizations should also consider implementing endpoint protection solutions that can detect and prevent exploitation attempts targeting boot process vulnerabilities.