CVE-2015-3708 in Mac OS X
Summary
by MITRE
kextd in kext tools in Apple OS X before 10.10.4 allows attackers to write to arbitrary files via a crafted app that conducts a symlink attack.
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Analysis
by VulDB Data Team • 04/24/2025
The vulnerability identified as CVE-2015-3708 resides within the kextd component of Apple's operating system, specifically affecting versions prior to 10.10.4. This issue represents a critical path traversal flaw that enables malicious actors to manipulate file system operations through crafted applications. The kextd service, responsible for managing kernel extensions on macOS, operates with elevated privileges and handles various kernel extension related tasks including loading, unloading, and management of kernel modules. When an application attempts to interact with kernel extensions through kextd, the system processes these requests through a series of file system operations that become vulnerable to manipulation by attackers.
The technical exploitation of this vulnerability occurs through a carefully crafted symlink attack that exploits improper path resolution within the kextd service. Attackers create symbolic links that point to arbitrary file locations, then execute malicious applications that trigger kextd to process these symbolic links. The flaw manifests when kextd fails to properly validate or sanitize file paths during kernel extension operations, allowing the system to follow symbolic links to unintended destinations. This type of vulnerability aligns with CWE-22 Path Traversal and CWE-367 Time-of-Check to Time-of-Use (TOCTOU) flaws, where the system checks file access permissions at one point but then operates on different file content at another point. The vulnerability specifically targets the file system access controls and privilege escalation mechanisms that should prevent unauthorized file modifications.
The operational impact of CVE-2015-3708 extends beyond simple file system manipulation, as it provides attackers with a pathway to modify critical system files and potentially escalate privileges to root access. When successful, this attack allows adversaries to write to arbitrary files on the system, potentially enabling them to modify system binaries, configuration files, or other critical components that control system behavior. The attack vector is particularly concerning because it requires minimal user interaction beyond running a malicious application, making it suitable for social engineering campaigns or drive-by attacks. The vulnerability can be leveraged to install persistent backdoors, modify system integrity checks, or compromise the overall security posture of the operating system. This aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as the flaw enables both initial access and subsequent privilege elevation.
Mitigation strategies for CVE-2015-3708 focus primarily on patching the affected operating system versions to 10.10.4 or later, where Apple implemented proper path validation and symlink handling within kextd. System administrators should also implement additional security controls including monitoring for suspicious file creation patterns, restricting kernel extension loading capabilities, and employing application whitelisting policies to prevent execution of untrusted applications. The vulnerability demonstrates the importance of proper privilege separation and input validation in system services, particularly those handling sensitive operations like kernel extension management. Organizations should conduct regular security assessments to identify similar path traversal vulnerabilities in other system components and maintain updated threat intelligence to detect potential exploitation attempts. Network monitoring solutions should be configured to detect anomalous file system activity that might indicate exploitation attempts, while endpoint protection systems should be updated to recognize malicious application behavior patterns associated with this vulnerability class.