CVE-2016-4646 in Mac OS X
Summary
by MITRE
Audio in Apple OS X before 10.11.6 mishandles a size value, which allows remote attackers to obtain sensitive information or cause a denial of service (out-of-bounds read) via a crafted audio file.
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Analysis
by VulDB Data Team • 09/06/2022
The vulnerability identified as CVE-2016-4646 represents a critical out-of-bounds read flaw within the audio handling components of Apple's macOS operating system versions prior to 10.11.6. This vulnerability resides in the core audio processing subsystem that manages various audio file formats and protocols, creating a potential attack vector that could be exploited by remote adversaries. The flaw specifically manifests when the system processes malformed audio files that contain manipulated size parameters, leading to improper memory access patterns that can result in information disclosure or system instability. The issue falls under the category of memory safety vulnerabilities and aligns with CWE-125, which describes out-of-bounds read conditions that occur when a program accesses memory beyond the boundaries of a buffer or array. Attackers can craft malicious audio files with deceptive size values that cause the operating system's audio processing engine to read memory locations outside the intended buffer boundaries, potentially exposing sensitive data from system memory or causing unexpected application crashes.
The technical implementation of this vulnerability exploits the lack of proper input validation within the audio file parsing routines. When macOS encounters an audio file with manipulated size fields, the system's audio decoder fails to properly validate the size parameters before attempting to allocate memory or process the audio data. This oversight allows attackers to manipulate the audio processing pipeline by embedding crafted size values that exceed the actual data boundaries, triggering memory access violations. The vulnerability's remote exploitability means that adversaries can deliver malicious audio files through various network channels including email attachments, web downloads, or malicious streaming content without requiring local system access. The out-of-bounds read condition can potentially expose kernel memory contents, including sensitive information such as cryptographic keys, user credentials, or system configuration data, depending on what memory locations are accessed during the malformed data processing. This type of vulnerability demonstrates a fundamental flaw in input sanitization and memory boundary checking that represents a classic example of insufficient validation of length fields in binary data structures.
The operational impact of CVE-2016-4646 extends beyond simple denial of service scenarios to encompass potential information disclosure and system compromise risks. Remote attackers who successfully exploit this vulnerability can cause applications to crash or behave unpredictably, leading to denial of service conditions that disrupt normal system operations. More critically, the out-of-bounds read could potentially expose sensitive information stored in memory, providing attackers with valuable data that could be used for further exploitation attempts or to facilitate more sophisticated attacks against the target system. The vulnerability affects a broad range of audio processing applications within the macOS ecosystem, including but not limited to the built-in audio players, media applications, and any software that relies on the system's audio handling capabilities. This widespread impact means that the vulnerability could be exploited across multiple attack vectors, making it particularly dangerous in enterprise environments where audio content is frequently processed through various applications and services.
The mitigation strategy for CVE-2016-4646 primarily involves upgrading to Apple macOS version 10.11.6 or later, which includes patches that address the flawed audio processing logic and implement proper size validation checks. System administrators should prioritize this update across all affected macOS systems to eliminate the vulnerability exposure. Additionally, organizations should implement network monitoring and content filtering measures to prevent the delivery of potentially malicious audio files through email systems, web proxies, or other network access points. The remediation process should include thorough testing of audio processing applications to ensure that the patches do not introduce compatibility issues or regressions in legitimate audio file handling. Security teams should also consider implementing application whitelisting policies that restrict the execution of audio processing applications from untrusted sources, reducing the attack surface for this and similar vulnerabilities. The vulnerability's classification under the ATT&CK framework would place it within the privilege escalation and defense evasion categories, as attackers could potentially use information disclosure from this vulnerability to gain further access to system resources or to craft more sophisticated attacks against the compromised systems.