CVE-2019-8539 in macOS
Summary
by MITRE • 10/28/2020
A memory initialization issue was addressed with improved memory handling. This issue is fixed in macOS Mojave 10.14.6, Security Update 2019-004 High Sierra, Security Update 2019-004 Sierra. A malicious application may be able to execute arbitrary code with system privileges.
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Analysis
by VulDB Data Team • 11/27/2020
The vulnerability identified as CVE-2019-8539 represents a critical memory initialization flaw that affected Apple's macOS operating system across multiple versions including Mojave 10.14.6 and earlier releases of High Sierra and Sierra. This issue stems from inadequate memory handling practices during the initialization phase of system processes, creating potential attack vectors for malicious actors seeking to escalate privileges. The flaw demonstrates the importance of proper memory management in operating system security, particularly when dealing with system-level operations that require elevated privileges. Security researchers have classified this vulnerability under CWE-754, which specifically addresses improper initialization of resources, highlighting how seemingly minor memory handling issues can have severe security implications. The vulnerability exists in the kernel-level memory management subsystem where insufficient validation of memory allocation and initialization processes creates opportunities for exploitation.
The technical exploitation of CVE-2019-8539 occurs when a malicious application leverages the improper memory initialization to gain unauthorized access to system privileges. Attackers can craft applications that manipulate memory allocation patterns during system boot or process initialization, potentially causing memory corruption that allows arbitrary code execution with root-level privileges. This type of vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and specifically targets the kernel memory management layer where the flaw resides. The attack vector typically involves a malicious application that can be installed on a target system through social engineering or other means, as the vulnerability requires only local execution capabilities to be exploited. The memory handling issue manifests as uninitialized memory being accessed before proper initialization, creating a potential buffer overflow or memory corruption scenario that attackers can leverage.
The operational impact of CVE-2019-8539 extends beyond simple privilege escalation to encompass potential system compromise and data theft capabilities. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with system-level privileges, effectively granting them complete control over the affected macOS system. This includes the ability to install malware, modify system files, access sensitive user data, and potentially establish persistence mechanisms within the compromised system. The vulnerability affects multiple versions of macOS, creating widespread exposure across enterprise and consumer environments, particularly in organizations that have not yet applied the relevant security updates. Organizations running affected versions of macOS are at risk of advanced persistent threats that can remain undetected for extended periods, as the exploitation techniques leverage legitimate system processes and memory management functions.
Mitigation strategies for CVE-2019-8539 primarily focus on applying the vendor-provided security updates that address the memory initialization issues in the affected macOS versions. System administrators should prioritize immediate deployment of macOS Mojave 10.14.6, Security Update 2019-004 for High Sierra, and Security Update 2019-004 for Sierra, as these patches contain the necessary fixes for the memory handling vulnerabilities. Additional defensive measures include implementing strict application control policies, monitoring for suspicious memory allocation patterns, and conducting regular security assessments of macOS systems. Organizations should also consider deploying endpoint protection solutions that can detect anomalous behavior patterns consistent with memory corruption exploits, particularly those targeting kernel-level operations. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and implementing layered security approaches that can detect and prevent exploitation attempts even when specific vulnerabilities are not yet patched. Security teams should monitor for indicators of compromise related to memory-based attacks and ensure that their incident response procedures include specific handling for kernel-level privilege escalation attempts.