CVE-2016-1791 in Mac OS X
Summary
by MITRE
The AMD subsystem in Apple OS X before 10.11.5 allows attackers to obtain sensitive kernel memory-layout information via a crafted app.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-1791 represents a significant information disclosure flaw within the AMD graphics subsystem of Apple's macOS operating system. This issue affects versions prior to macOS 10.11.5 and stems from insufficient memory protection mechanisms that allow malicious applications to extract kernel memory layout details through carefully crafted software. The vulnerability specifically targets the graphics driver component that interfaces with AMD hardware, creating an avenue for attackers to gain insights into the kernel's memory organization that should remain protected from user-space applications.
The technical implementation of this vulnerability involves a flaw in how the AMD graphics driver handles memory access controls and privilege boundaries within the kernel space. When a crafted application executes, it can leverage improper memory management techniques to read kernel memory addresses and layout information that should be inaccessible to regular user processes. This type of information disclosure can reveal critical details about the kernel's memory mapping, which is classified as a weakness under CWE-200, specifically concerning the exposure of sensitive information through improper access controls. The vulnerability demonstrates a failure in the principle of least privilege and proper memory isolation between user-space applications and kernel-space operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as the leaked memory layout information can serve as a foundation for more sophisticated attacks. Attackers can utilize the disclosed kernel memory addresses to craft more effective exploits by understanding memory organization patterns, which may facilitate subsequent buffer overflow attacks, return-oriented programming exploits, or other advanced techniques that rely on knowledge of memory layout. This vulnerability aligns with ATT&CK technique T1059.003, which involves the use of application execution commands, and T1068, which covers the exploitation of remote services. The information obtained through this vulnerability can significantly reduce the complexity of future attack vectors by removing the need for extensive reconnaissance to understand the target system's memory structure.
Mitigation strategies for CVE-2016-1791 primarily involve upgrading to macOS 10.11.5 or later versions where Apple has implemented proper memory protection mechanisms and access controls within the AMD graphics subsystem. System administrators should ensure all endpoints are updated promptly to address this vulnerability. Additional protective measures include implementing application whitelisting policies that restrict the execution of untrusted applications, particularly those that might attempt to access kernel memory directly. The fix implemented by Apple likely involves strengthening memory access controls and ensuring proper privilege separation between graphics driver components and kernel memory spaces, addressing the underlying CWE-200 vulnerability through enhanced memory protection mechanisms. Organizations should also consider monitoring for suspicious application behavior that might indicate attempts to exploit this or similar information disclosure vulnerabilities.