CVE-2019-8582 in iOS
Summary
by MITRE • 10/28/2020
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in iCloud for Windows 7.12, tvOS 12.3, iTunes 12.9.5 for Windows, macOS Mojave 10.14.5, Security Update 2019-003 High Sierra, Security Update 2019-003 Sierra, iOS 12.3. Processing a maliciously crafted font may result in the disclosure of process memory.
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Analysis
by VulDB Data Team • 11/28/2020
The vulnerability identified as CVE-2019-8582 represents a critical out-of-bounds read flaw that affects multiple Apple operating systems and applications. This security issue was discovered in the font processing components of Apple's ecosystem, specifically impacting how the system handles malformed or maliciously crafted font files. The vulnerability stems from inadequate bounds checking during font parsing operations, which allows an attacker to manipulate the parsing logic and potentially access memory locations beyond the intended buffer boundaries. This type of flaw falls under the CWE-129 weakness category, which specifically addresses improper validation of array indices and buffer bounds, making it a direct descendant of the broader class of buffer overflow vulnerabilities that have plagued software systems for decades.
The technical implementation of this vulnerability occurs when Apple's applications process font files that contain crafted malicious data structures. During normal font parsing operations, the system allocates memory buffers to store font metadata and rendering information. However, the insufficient bounds checking allows an attacker to provide font data that exceeds the allocated buffer size, causing the application to read memory locations that should not be accessible. This out-of-bounds memory access can result in information disclosure, where sensitive process memory contents become accessible to the attacker. The vulnerability affects multiple platforms including macOS, iOS, tvOS, and Windows versions of iCloud and iTunes, indicating a widespread impact across Apple's ecosystem and demonstrating the complexity of maintaining consistent security across diverse operating environments.
The operational impact of CVE-2019-8582 extends beyond simple information disclosure, as the memory disclosure could potentially reveal sensitive data such as cryptographic keys, user credentials, or application state information. Attackers could exploit this vulnerability by crafting malicious font files and distributing them through various attack vectors including email attachments, web downloads, or compromised websites. The attack surface is particularly concerning given that font files are commonly encountered in legitimate use cases, making the attack vector both accessible and difficult to detect. This vulnerability aligns with ATT&CK technique T1059.007 for Windows, as it could be exploited through script-based font processing, and represents a classic example of how seemingly benign file formats can become attack vectors in modern computing environments.
Apple's response to this vulnerability involved implementing improved bounds checking mechanisms across all affected platforms and applications. The fix was rolled out through multiple security updates including iCloud for Windows 7.12, tvOS 12.3, iTunes 12.9.5 for Windows, and various macOS security updates. The remediation approach focused on strengthening input validation and memory management during font processing operations, ensuring that all buffer accesses are properly validated before execution. This fix exemplifies the importance of defensive programming practices and demonstrates how security vulnerabilities can be addressed through proper bounds checking implementations. Organizations should prioritize applying these updates immediately, as the vulnerability could be exploited in the wild, and the memory disclosure capabilities make it particularly dangerous for environments handling sensitive data. The vulnerability also underscores the importance of supply chain security, as font files are often used in legitimate applications and could serve as a vector for more sophisticated attacks.