CVE-2016-7655 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 10.2 is affected. macOS before 10.12.2 is affected. The issue involves the "CoreMedia External Displays" component. It allows local users to gain privileges or cause a denial of service (type confusion) via unspecified vectors.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-7655 represents a critical type confusion flaw within Apple's CoreMedia External Displays component that affects multiple operating systems including iOS versions prior to 10.2 and macOS versions prior to 10.12.2. This issue resides in the kernel-level subsystem responsible for managing external display connections and media processing, making it particularly dangerous as it operates with elevated privileges. The type confusion vulnerability occurs when the system incorrectly handles data types during processing, leading to potential arbitrary code execution or system instability. According to CWE-466, this vulnerability falls under the category of improper handling of pointer type confusion, where the system fails to properly validate data types during memory operations. The attack vector for this vulnerability is particularly concerning as it allows local users to exploit the flaw without requiring network connectivity or user interaction, making it highly accessible to threat actors with physical access to affected devices.
The technical implementation of this vulnerability stems from improper memory management within the CoreMedia framework that handles external display protocols and media processing. When the system processes external display connections, it fails to properly validate the data types of incoming parameters, allowing an attacker to manipulate memory structures through crafted inputs. This type confusion can result in the execution of arbitrary code with kernel privileges, effectively bypassing standard security boundaries. The vulnerability's impact extends beyond simple privilege escalation as it can also lead to denial of service conditions where the system becomes unstable or crashes entirely. The flaw is particularly dangerous because it operates within the kernel space where the system's most critical functions reside, meaning successful exploitation can compromise the entire operating system. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting kernel-level vulnerabilities that allow attackers to gain administrative control over affected systems.
From an operational perspective, this vulnerability presents significant risk to organizations and individual users who rely on Apple devices for sensitive operations. The local exploitation requirement means that physical access to the device is sufficient for an attacker to compromise the system, which could occur in scenarios such as lost or stolen devices, insider threats, or unsecured physical access environments. The vulnerability affects a core component that handles external display connections, making it particularly concerning for enterprise environments where devices frequently connect to external monitors, projectors, or docking stations. Security professionals must consider that this vulnerability could be leveraged as part of a broader attack chain, potentially serving as a foothold for more sophisticated attacks. The lack of specific vector details in the original description indicates that the flaw may be exploitable through multiple attack paths, including malformed display protocol data or malicious external hardware connections, which complicates both detection and remediation efforts.
Mitigation strategies for CVE-2016-7655 require immediate action to update affected systems to the patched versions of iOS 10.2 and macOS 10.12.2, which contain the necessary security patches to address the type confusion vulnerability. Organizations should implement comprehensive patch management policies that prioritize critical security updates, especially for operating systems that handle sensitive data or provide access to critical infrastructure. System administrators should conduct thorough vulnerability assessments to identify all affected devices and ensure that updates are deployed across all endpoints. Additional defensive measures include monitoring for unusual system behavior that might indicate exploitation attempts, implementing device access controls to limit physical access to critical systems, and maintaining detailed inventory records of all devices to facilitate rapid response to security incidents. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how seemingly minor components like external display management can contain critical security flaws that affect system integrity and user privacy. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation, particularly in environments where multiple users share devices or where physical security controls may be insufficient.