CVE-2016-1820 in Mac OS X
Summary
by MITRE
Buffer overflow in IOAudioFamily in Apple OS X before 10.11.5 allows attackers to execute arbitrary code in a privileged context via a crafted app.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 11/05/2024
The vulnerability identified as CVE-2016-1820 represents a critical buffer overflow flaw within the IOAudioFamily component of Apple's macOS operating system. This issue affects versions prior to macOS 10.11.5 and resides in the kernel-level audio subsystem that handles audio device interactions. The buffer overflow occurs when the system processes malformed audio data structures, specifically within the audio family framework that manages various audio hardware interfaces. The vulnerability stems from insufficient input validation and bounds checking mechanisms in the kernel extension responsible for audio device management, creating an exploitable condition that can be leveraged by malicious actors to gain elevated privileges.
The technical implementation of this vulnerability involves a classic buffer overflow scenario where an attacker crafts a malicious application that sends specially formatted audio data to the IOAudioFamily kernel extension. When the kernel processes this malformed data, it fails to properly validate the buffer boundaries, leading to memory corruption that can be exploited to overwrite critical kernel memory regions. This flaw operates at the kernel level, meaning successful exploitation results in code execution with the highest possible privileges, effectively granting attackers root access to the affected system. The vulnerability is particularly dangerous because it requires no user interaction beyond running the malicious application, making it a prime target for automated exploitation campaigns.
The operational impact of CVE-2016-1820 extends beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities. Once exploited, adversaries can install persistent backdoors, modify system files, access encrypted data, and perform network reconnaissance without detection. The vulnerability affects all macOS versions before 10.11.5, including major releases such as macOS El Capitan and earlier versions, creating a substantial attack surface across numerous deployed systems. Security researchers have noted that this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and demonstrates how kernel-level buffer overflows can be weaponized for system takeover. The exploitability of this flaw has been documented in various threat actor toolkits, making it a commonly targeted vulnerability in advanced persistent threat campaigns.
Mitigation strategies for CVE-2016-1820 primarily focus on immediate system updates and security hardening measures. Apple released macOS 10.11.5 to address this vulnerability, which includes memory protection enhancements and improved input validation within the IOAudioFamily framework. Organizations should prioritize immediate deployment of this security update across all affected systems, as the vulnerability has been actively exploited in the wild. Additional defensive measures include implementing kernel extension restrictions, enabling System Integrity Protection where available, and monitoring for unusual audio-related processes or network connections that might indicate exploitation attempts. Security teams should also consider implementing runtime application control policies to prevent execution of unsigned or untrusted audio-related applications that could potentially trigger the vulnerability. The remediation approach aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, as attackers often leverage such privilege escalation capabilities to establish persistent access to compromised systems.