CVE-2016-4696 in macOS
Summary
by MITRE
AppleEFIRuntime in Apple OS X before 10.12 allows attackers to execute arbitrary code in a privileged context or cause a denial of service (NULL pointer dereference) via a crafted app.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/20/2022
The vulnerability identified as CVE-2016-4696 resides within AppleEFIRuntime, a critical component of Apple's operating system that interfaces with the Extensible Firmware Interface runtime environment. This flaw exists in Apple OS X versions prior to 10.12, representing a significant security weakness that could be exploited by malicious actors to gain elevated privileges or disrupt system operations. The vulnerability specifically manifests through a NULL pointer dereference condition that occurs when processing crafted applications, making it particularly dangerous as it can be triggered through seemingly benign software execution.
The technical implementation of this vulnerability stems from inadequate input validation within the AppleEFIRuntime subsystem. When a malicious application is executed, the runtime environment fails to properly validate certain parameters before attempting to dereference memory pointers. This NULL pointer dereference creates an opportunity for attackers to manipulate the execution flow of the privileged runtime environment, potentially allowing them to execute arbitrary code with elevated privileges. The flaw operates at a fundamental level within the system's boot and firmware runtime processes, making it particularly challenging to detect and mitigate.
From an operational perspective, this vulnerability presents a severe threat to system integrity and availability. Attackers can leverage this weakness to either escalate their privileges to system-level access or to induce a denial of service condition that could render the affected system unusable. The privilege escalation aspect is particularly concerning as it could enable attackers to bypass standard security controls and gain access to sensitive system resources. The potential for denial of service means that even a single compromised application could bring down critical system functions, affecting both individual users and enterprise environments that depend on stable operating system performance.
The impact of CVE-2016-4696 aligns with CWE-476, which specifically addresses NULL pointer dereference vulnerabilities, and demonstrates characteristics consistent with techniques described in the MITRE ATT&CK framework under privilege escalation and execution tactics. Organizations running affected versions of Apple OS X are particularly vulnerable to this attack vector as it operates at a low-level system interface that is difficult to monitor and protect through traditional application-level security measures. The vulnerability's exploitation requires minimal technical expertise, making it accessible to threat actors across different skill levels. Remediation efforts should prioritize immediate system updates to Apple OS X 10.12 or later versions, while organizations should implement additional monitoring for suspicious execution patterns within their network environments to detect potential exploitation attempts.
This vulnerability serves as a critical reminder of the importance of firmware security and the need for comprehensive security testing across all system layers. The fact that it can be triggered through standard application execution makes it particularly dangerous as it may not require specialized attack tools or techniques. System administrators should also consider implementing additional security controls such as application whitelisting and runtime protection mechanisms to provide defense-in-depth against similar vulnerabilities. Regular security assessments and patch management processes become essential to maintain system integrity against threats that exploit low-level system components like AppleEFIRuntime.