CVE-2019-8639 in Safari
Summary
by MITRE • 10/28/2020
Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in watchOS 5.2, iCloud for Windows 7.11, iOS 12.2, iTunes 12.9.4 for Windows, Safari 12.1. Processing maliciously crafted web content may lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 11/28/2020
The vulnerability identified as CVE-2019-8639 represents a critical memory corruption issue affecting multiple Apple operating systems and applications. This flaw resides in the memory handling mechanisms of Apple's ecosystem, specifically impacting iOS 12.2, watchOS 5.2, iCloud for Windows 7.11, iTunes 12.9.4 for Windows, and Safari 12.1. The vulnerability stems from insufficient validation and improper memory management when processing web content, creating opportunities for attackers to exploit memory corruption patterns that could lead to arbitrary code execution. The issue demonstrates the inherent complexity of modern web browsers and operating systems where memory safety mechanisms must account for various input vectors and execution contexts. According to CWE classification, this vulnerability maps to CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions, both of which are common manifestations of memory corruption vulnerabilities in software systems. The ATT&CK framework categorizes this as a privilege escalation technique through memory corruption, specifically under T1068, which involves exploiting legitimate credentials and privileges to gain higher-level access.
The technical exploitation of CVE-2019-8639 occurs when maliciously crafted web content is processed by affected applications, particularly Safari browser and iOS applications that render web pages. The memory corruption manifests during the parsing and rendering of specially crafted HTML, JavaScript, or multimedia content that triggers buffer overflows or use-after-free conditions in the underlying memory management systems. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected application, potentially leading to full system compromise. The exploitation process typically involves crafting web content that, when loaded, causes the application to write data beyond allocated memory boundaries or access freed memory locations, resulting in unpredictable behavior that can be controlled to execute malicious payloads. The vulnerability's impact extends across multiple platforms due to shared codebases and similar memory handling patterns in Apple's software architecture.
The operational impact of CVE-2019-8639 poses significant risks to enterprise and individual users alike, as it affects core productivity applications and operating systems that handle internet content regularly. Organizations with iOS or macOS devices face potential data breaches, system compromise, and unauthorized access to sensitive information when users visit malicious websites or open compromised web content. The vulnerability's exploitation requires only web-based interaction, making it particularly dangerous in environments where users frequently access untrusted websites or receive phishing emails with embedded malicious content. Security professionals must consider this vulnerability as part of their risk assessment for mobile and desktop environments, particularly in sectors handling sensitive data such as healthcare, finance, or government operations. The widespread nature of affected applications means that a successful exploitation could potentially impact thousands of devices across different organizations simultaneously.
Mitigation strategies for CVE-2019-8639 primarily focus on immediate patch deployment and operational security measures. Apple has addressed this vulnerability through security updates for iOS 12.2, watchOS 5.2, iCloud for Windows 7.11, iTunes 12.9.4 for Windows, and Safari 12.1, implementing improved memory handling and validation mechanisms. Organizations should prioritize immediate deployment of these security patches across all affected systems and maintain strict update policies to prevent exploitation. Network security measures including web filtering, sandboxing of web content, and monitoring for suspicious web traffic can provide additional layers of protection. Security teams should also implement behavioral monitoring to detect anomalous application behavior that might indicate exploitation attempts, particularly focusing on memory access patterns and privilege escalation activities. Regular security assessments and vulnerability scanning should include checks for this specific vulnerability to ensure comprehensive protection across the organization's digital infrastructure.