CVE-2020-9873 in iCloud
Summary
by MITRE • 10/23/2020
An out-of-bounds read was addressed with improved input validation. 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, iTunes 12.10.8 for Windows, iCloud for Windows 11.3, iCloud for Windows 7.20. Processing a maliciously crafted image may lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 11/09/2020
The vulnerability identified as CVE-2020-9873 represents a critical out-of-bounds read flaw that existed within Apple's multimedia processing libraries across multiple operating systems and applications. This issue was particularly concerning because it could be triggered through the processing of maliciously crafted image files, potentially allowing attackers to execute arbitrary code on affected systems. The vulnerability demonstrates the inherent risks associated with image parsing libraries that fail to properly validate input boundaries, creating opportunities for attackers to manipulate memory access patterns and gain unauthorized system control.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where programs access memory locations beyond the allocated buffer boundaries. This specific flaw occurred during image file processing within Apple's core frameworks, where insufficient input validation allowed attackers to craft specially formatted image files that would cause the application to read memory beyond intended buffer limits. The exploitation mechanism leverages the typical memory corruption patterns associated with buffer over-read conditions, where attackers can manipulate the program flow by controlling what data is read from memory locations that should remain inaccessible.
The operational impact of CVE-2020-9873 extends across multiple Apple platforms including iOS, iPadOS, macOS, tvOS, and watchOS, making it a widespread concern for organizations relying on Apple ecosystems. The vulnerability's presence in iTunes and iCloud for Windows applications further amplifies its reach, as these components are frequently used in enterprise environments and by individual users for data synchronization and backup operations. Attackers could potentially exploit this flaw through social engineering campaigns that deliver malicious image files via email attachments, web downloads, or compromised websites, making the attack surface particularly broad and difficult to monitor comprehensively.
The exploitation of this vulnerability follows attack patterns consistent with the ATT&CK framework's technique T1059.007 for command and script interpreter, where the arbitrary code execution capability allows attackers to deploy additional payloads or establish persistent access. The fix implemented by Apple in versions iOS 13.6, iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, and watchOS 6.2.8 included enhanced input validation mechanisms that properly bounds-check image file data before processing. These mitigations address the root cause by ensuring that all image parsing operations validate buffer boundaries and reject malformed input before attempting to access memory locations. Organizations should prioritize immediate deployment of these updates across all affected systems to prevent potential exploitation.
The broader implications of this vulnerability highlight the importance of robust input validation in multimedia processing libraries, particularly those handling untrusted user data. This flaw exemplifies how seemingly benign file processing operations can become attack vectors when proper boundary checking is omitted. Security professionals should implement monitoring for suspicious image file handling activities and maintain awareness of similar vulnerabilities in third-party libraries that may be integrated into Apple applications. The remediation process should include comprehensive testing of image processing functionality to ensure that the input validation changes do not introduce performance regressions or compatibility issues with legitimate image files.
The vulnerability's classification as a remote code execution threat underscores the need for layered security approaches that include network monitoring, endpoint protection, and regular security assessments. Organizations should consider implementing network segmentation to limit the potential impact of successful exploitation, while also maintaining up-to-date threat intelligence to identify potential attack campaigns targeting this specific vulnerability. The fix demonstrates Apple's commitment to addressing security issues in their ecosystem, but also serves as a reminder that even well-established software platforms can contain critical vulnerabilities that require ongoing vigilance and proactive security measures from both vendors and users.