CVE-2020-9888 in macOS
Summary
by MITRE • 10/16/2020
An out-of-bounds read 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-2020-9888 represents a critical out-of-bounds read flaw within Apple's multimedia processing libraries that affects multiple operating systems including iOS, iPadOS, macOS, tvOS, and watchOS. This issue stems from insufficient bounds checking mechanisms when processing audio files, creating a scenario where maliciously crafted audio data can trigger memory access violations that extend beyond allocated buffer boundaries. The flaw exists in the underlying audio decoding and processing components that handle various audio formats, particularly those involving complex metadata structures or specialized encoding schemes. The vulnerability manifests when the system attempts to parse audio files that contain malformed or specially constructed data elements that exceed expected parameter limits, leading to unpredictable memory access patterns that can be exploited by attackers.
The technical exploitation of this vulnerability follows a well-defined attack pattern that aligns with common software security principles and attack methodologies documented in the attack mitigation framework. An attacker can craft audio files with specifically designed buffer overflows that cause the system to read memory locations beyond the intended boundaries of the audio data structure. This out-of-bounds memory access can result in information disclosure, system instability, or more critically, arbitrary code execution within the context of the affected application or system service. The attack vector is particularly concerning as it requires no user interaction beyond the mere presentation of the malicious file, making it a prime candidate for drive-by exploitation scenarios. The vulnerability demonstrates characteristics consistent with CWE-129, which describes improper validation of length of input buffers, and can be mapped to ATT&CK technique T1059.007 for command and scripting interpreter execution through legitimate system processes.
The operational impact of CVE-2020-9888 extends beyond simple system crashes or performance degradation, potentially enabling full system compromise and persistent access for threat actors. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with the privileges of the affected system component, which could range from sandboxed media applications to system-level services. The attack surface includes any application or service that processes audio files, including media players, messaging applications, web browsers, and file sharing platforms. The implications are particularly severe in enterprise environments where users may encounter malicious audio files through email attachments, file transfers, or web-based media content. The vulnerability also presents challenges for mobile device security as it affects Apple's ecosystem across multiple platforms, requiring coordinated patch management and security updates across various device types and operating system versions.
Apple's patch for CVE-2020-9888 implements enhanced bounds checking mechanisms that validate all buffer access operations and ensure proper parameter validation before memory operations occur. The fix addresses the root cause by introducing additional safety checks that prevent memory access violations when processing malformed audio data structures. Organizations should prioritize deployment of the applicable security updates for iOS 13.6, iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, and watchOS 6.2.8 to remediate this vulnerability. Additional mitigations include implementing network-based filtering to block suspicious audio file types, deploying endpoint protection solutions with behavioral monitoring capabilities, and establishing security awareness programs to educate users about the risks of opening untrusted audio content. The vulnerability also highlights the importance of maintaining up-to-date security patches and demonstrates how seemingly benign media processing functions can become attack vectors when proper input validation is absent. Security teams should conduct vulnerability assessments to identify systems running affected versions and implement continuous monitoring to detect potential exploitation attempts.