CVE-2020-9889 in macOS
Summary
by MITRE • 10/16/2020
An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.6 and iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, watchOS 6.2.8. Processing a maliciously crafted audio file may lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 11/03/2020
The vulnerability identified as CVE-2020-9889 represents a critical out-of-bounds write flaw that existed within Apple's multimedia processing frameworks. This issue specifically affected the handling of audio files within the operating system's core media libraries, where insufficient bounds checking allowed maliciously crafted audio data to trigger memory corruption. The vulnerability falls under the CWE-787 category of out-of-bounds write conditions, which is a fundamental memory safety issue that can lead to unpredictable system behavior and potential exploitation. The flaw was present in multiple Apple operating systems including iOS 13.5 and earlier versions, iPadOS 13.5 and earlier, macOS Catalina 10.15.5 and earlier, tvOS 13.4.7 and earlier, and watchOS 6.2.7 and earlier versions. Attackers could exploit this vulnerability by crafting specially formatted audio files designed to trigger the memory corruption during normal playback operations, potentially leading to complete system compromise.
The technical implementation of this vulnerability stems from inadequate input validation within Apple's audio processing pipelines. When the system attempts to parse and process malformed audio files, the lack of proper bounds checking allows data to be written beyond the allocated memory buffer boundaries. This memory corruption can overwrite critical system data structures, function pointers, or executable code segments, providing attackers with opportunities to execute arbitrary code with the privileges of the affected process. The exploitability of this vulnerability is particularly concerning because audio files are commonly encountered through various legitimate means such as email attachments, web downloads, or media streaming services, making the attack surface quite broad. The issue demonstrates how multimedia processing components can serve as attack vectors, as they often handle untrusted input data without sufficient sanitization measures.
The operational impact of CVE-2020-9889 extends beyond simple system instability, representing a significant threat to user security and system integrity across Apple's ecosystem. Successful exploitation could allow attackers to gain full control over affected devices, potentially enabling them to install malicious software, access sensitive user data, monitor communications, or establish persistent backdoors. The vulnerability's presence in multiple operating systems means that organizations and individuals using Apple devices across various platforms face similar risks, requiring coordinated patch management efforts. The exploitability of this flaw through audio file processing aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers could potentially use the arbitrary code execution capability to deploy additional payloads or establish command and control channels. Organizations relying on Apple devices for business operations must consider the broader implications of this vulnerability on their overall security posture.
Apple addressed this vulnerability through comprehensive bounds checking improvements implemented in their security updates released alongside iOS 13.6, iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, and watchOS 6.2.8. These updates introduced enhanced input validation mechanisms specifically targeting the audio processing components where the vulnerability existed. The mitigation strategy focused on strengthening memory boundary checks and implementing more robust data sanitization procedures for audio file parsing operations. System administrators and users should prioritize immediate deployment of these security updates across all affected Apple devices to eliminate the risk of exploitation. Additional defensive measures include implementing network-based filtering to block suspicious audio file downloads, maintaining up-to-date backup procedures, and monitoring for unusual system behavior that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of memory safety in multimedia processing components and the necessity of thorough input validation in all system components handling external data.