CVE-2015-5891 in Mac OS X
Summary
by MITRE
The SMB implementation in the kernel in Apple OS X before 10.11 allows local users to gain privileges or cause a denial of service (memory corruption) via unspecified vectors.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2015-5891 represents a critical security flaw within the Server Message Block implementation in Apple's macOS kernel, affecting versions prior to 10.11. This issue resides in the core operating system kernel components that handle network file sharing protocols, specifically the SMB protocol stack that enables file and printer sharing across networks. The vulnerability's presence in the kernel level architecture means that any exploitation could potentially compromise the entire system integrity and provide attackers with elevated privileges. The unspecified vectors suggest that multiple attack surfaces within the SMB implementation could be leveraged by malicious actors, making the vulnerability particularly concerning from a security research perspective. The vulnerability affects the fundamental networking capabilities of macOS systems, particularly those that utilize SMB for file sharing operations.
The technical nature of this vulnerability involves memory corruption issues that occur within the kernel's SMB processing code, which can be triggered through malformed SMB protocol messages or improper handling of network requests. Such memory corruption vulnerabilities typically arise from insufficient input validation, buffer overflows, or improper memory management within kernel space code. The fact that this vulnerability exists in the kernel implementation means that local users could potentially exploit it to escalate privileges from standard user accounts to root level access, or alternatively cause system crashes and denial of service conditions. The kernel-level nature of the flaw also means that traditional user-space protections and sandboxing mechanisms would not prevent exploitation, as the vulnerability operates at the system's most privileged execution level.
From an operational impact perspective, this vulnerability creates significant risks for macOS environments, particularly those that rely heavily on network file sharing services or have multiple users with varying privilege levels. Local privilege escalation vulnerabilities are particularly dangerous because they require minimal attack vectors and can be exploited by users who already have access to the system. Organizations running affected macOS versions may experience unauthorized access to sensitive data, system compromise, and potential lateral movement within network environments where SMB services are active. The denial of service component of this vulnerability means that even without privilege escalation, attackers could disrupt services by causing system crashes or memory corruption that leads to system instability and potential data loss. This vulnerability could be particularly problematic in enterprise environments where macOS systems serve as file servers or where users have legitimate access to network resources.
Security mitigations for CVE-2015-5891 should focus on immediate system updates to macOS 10.11 or later versions where Apple has patched the kernel-level SMB implementation. Organizations should also consider implementing network segmentation and access controls to limit potential exploitation vectors, particularly by disabling unnecessary SMB services on systems that do not require them. System administrators should monitor for signs of exploitation attempts and implement proper logging mechanisms to detect anomalous SMB traffic patterns. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in kernel implementations, and may also relate to CWE-787, representing out-of-bounds write vulnerabilities in kernel space. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could be leveraged as part of initial access or lateral movement phases in attack campaigns. Organizations should also consider implementing endpoint detection and response solutions that can identify unusual memory access patterns or kernel-level anomalies that may indicate exploitation attempts. Regular security assessments of macOS systems should include verification of SMB service configurations and monitoring for potential exploitation indicators in network traffic logs.