CVE-2019-8838 in tvOS
Summary
by MITRE • 10/28/2020
A memory corruption issue was addressed with improved memory handling. 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.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/29/2020
The vulnerability identified as CVE-2019-8838 represents a critical memory corruption flaw that existed within Apple's operating systems, specifically affecting iOS, iPadOS, watchOS, macOS, and tvOS versions prior to their respective security updates. This issue stems from inadequate memory handling mechanisms that could be exploited by malicious applications to gain unauthorized access to kernel-level privileges. The vulnerability falls under the category of memory safety issues and is classified as a heap-based buffer overflow according to CWE-121 standards, where improper memory management allows for arbitrary code execution. The flaw specifically impacts the kernel's memory allocation and deallocation processes, creating potential entry points for attackers to escalate their privileges from user-level applications to system-level operations.
The technical exploitation of this vulnerability enables a malicious application to execute arbitrary code with kernel privileges, which fundamentally compromises the operating system's security model. This type of privilege escalation is particularly dangerous because it allows attackers to bypass the kernel's protection mechanisms and gain complete control over the system. The memory corruption occurs during the handling of memory operations, where the system fails to properly validate memory boundaries or handle memory deallocation correctly, leading to potential overwrite conditions. Attackers could leverage this flaw by crafting malicious applications that trigger the vulnerable memory handling code paths, potentially causing the system to execute unintended code sequences with elevated privileges. The ATT&CK framework categorizes this as privilege escalation through kernel exploits, specifically mapping to technique T1068 which involves exploiting vulnerabilities in operating system kernels to gain elevated privileges.
The operational impact of CVE-2019-8838 extends beyond simple privilege escalation, as it represents a fundamental breach in the security architecture of affected Apple devices. Systems running vulnerable versions become susceptible to persistent malware installations that can operate at the kernel level, making detection and removal extremely difficult. The vulnerability affects all supported Apple operating systems including iOS 13.2 and earlier, macOS Catalina 10.15.1 and earlier, watchOS 6.1 and earlier, and tvOS 13.2 and earlier, creating widespread exposure across Apple's ecosystem. Organizations and individual users face significant risks as this vulnerability could be exploited by sophisticated attackers to establish persistent backdoors, exfiltrate sensitive data, or deploy additional malicious payloads. The security implications are particularly severe for enterprise environments where Apple devices are commonly used for business operations, as compromise of a single device could potentially lead to broader network infiltration.
Apple addressed this vulnerability through comprehensive security updates released as part of iOS 13.3, iPadOS 13.3, watchOS 6.1.1, macOS Catalina 10.15.2, and the respective security updates for Mojave and High Sierra. These updates implemented improved memory handling mechanisms, including enhanced bounds checking, proper memory deallocation procedures, and strengthened kernel memory management protocols. The mitigation strategies employed by Apple focus on preventing the specific memory corruption patterns that enabled exploitation, effectively closing the attack vectors that could be used to achieve kernel privilege escalation. Security researchers and organizations should prioritize deployment of these updates across all affected systems to eliminate the risk of exploitation. The fix demonstrates Apple's approach to addressing memory safety vulnerabilities through proactive patch management and enhanced code review processes, aligning with industry best practices for maintaining secure operating system implementations. Organizations should also implement additional security measures including network monitoring, application whitelisting, and regular security assessments to further protect against potential exploitation attempts that may target unpatched systems.