CVE-2019-8833 in tvOS
Summary
by MITRE • 10/28/2020
A memory corruption issue was addressed by removing the vulnerable code. This issue is fixed in iOS 13.3 and iPadOS 13.3, watchOS 6.1.1, macOS Catalina 10.15.2, Security Update 2019-002 Mojave, and Security Update 2019-007 High Sierra, tvOS 13.3. An application may be able to execute arbitrary code with kernel privileges.
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Analysis
by VulDB Data Team • 11/29/2020
This vulnerability represents a critical memory corruption flaw that existed in multiple Apple operating systems including iOS, iPadOS, watchOS, macOS, and tvOS. The issue was classified as a kernel-level vulnerability that could potentially allow malicious applications to escalate privileges and execute arbitrary code with the highest level of system permissions. The vulnerability was addressed through the complete removal of the problematic code rather than implementing a patch, indicating the severity and risk associated with the memory corruption mechanism. This approach to remediation aligns with security best practices when dealing with fundamental architecture flaws that could be exploited to gain complete system control.
The technical nature of this vulnerability falls under memory corruption patterns that can be categorized as a weakness in the operating system's memory management subsystem. Memory corruption vulnerabilities typically occur when applications or processes can manipulate memory in ways that were not intended by the system designers, potentially leading to arbitrary code execution or privilege escalation. The fact that this issue required kernel-level privilege execution indicates that it was likely related to improper memory handling in system-level components that manage core operating functions. Such vulnerabilities often map to CWE-121, which describes stack-based buffer overflow conditions, or CWE-122, which covers heap-based buffer overflows, though the exact technical mechanism would depend on the specific implementation details of the vulnerable code.
The operational impact of this vulnerability was severe as it provided a pathway for malicious applications to bypass security controls and gain root access to affected systems. This type of privilege escalation allows attackers to completely compromise the device, potentially accessing sensitive user data, installing additional malware, or using the compromised device as a foothold for further attacks. The vulnerability affected multiple platforms simultaneously, suggesting it was likely present in shared kernel components or system libraries that were common across Apple's ecosystem. This cross-platform nature increases the attack surface and makes the vulnerability particularly concerning for organizations that rely on Apple devices for security-critical operations.
The remediation approach taken by Apple involved complete code removal rather than patching, which indicates the vulnerability was fundamental to the system architecture rather than a simple coding error. This method of remediation is typically employed when the risk of exploitation is extremely high or when patching the specific issue could introduce instability. The security updates released for this vulnerability covered all affected operating systems including iOS 13.3, iPadOS 13.3, watchOS 6.1.1, macOS Catalina 10.15.2, and the corresponding security updates for Mojave and High Sierra. Organizations should have prioritized deployment of these updates as they represented a critical security measure to prevent potential exploitation. The vulnerability's classification as a kernel-level privilege escalation aligns with ATT&CK technique T1068, which describes local privilege escalation, and demonstrates how memory corruption can be leveraged to achieve system-level control. This type of vulnerability also relates to the broader category of zero-day exploits that can be particularly dangerous due to their potential for widespread impact across multiple platforms and their ability to bypass traditional security controls.