CVE-2020-9927 in macOS
Summary
by MITRE • 10/23/2020
A memory corruption issue was addressed with improved input validation. This issue is fixed in macOS Catalina 10.15.6. An application may be able to execute arbitrary code with kernel privileges.
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Analysis
by VulDB Data Team • 11/26/2020
This vulnerability represents a critical memory corruption flaw that existed in Apple's macOS operating system, specifically affecting versions prior to Catalina 10.15.6. The issue stems from inadequate input validation mechanisms within the kernel, creating a pathway for malicious applications to escalate their privileges and execute arbitrary code with the highest level of system access. The vulnerability classifies under CWE-121, which encompasses buffer overflow conditions, and more specifically aligns with CWE-787, representing out-of-bounds write vulnerabilities that can lead to memory corruption. From an operational perspective, this flaw represents a severe privilege escalation vector that directly violates the principle of least privilege and could enable attackers to gain complete system control.
The technical exploitation of this vulnerability occurs when an application submits malformed input to kernel-level functions that lack proper validation checks. This allows the attacker to manipulate memory layout and potentially overwrite critical kernel structures, leading to arbitrary code execution with kernel privileges. The attack surface is particularly concerning because it requires no user interaction beyond running the malicious application, making it a latent threat that can be silently exploited in the background. This vulnerability directly maps to ATT&CK technique T1068, which describes the exploitation of legitimate credentials and system privileges for privilege escalation, and T1059, covering the execution of malicious code through system processes. The memory corruption aspect specifically relates to the kernel's memory management subsystem where the lack of proper bounds checking allows attackers to corrupt memory regions that should remain protected.
The operational impact of CVE-2020-9927 extends beyond simple privilege escalation, as successful exploitation can enable attackers to bypass all kernel-level security controls including System Integrity Protection, code signing enforcement, and other critical security mechanisms. This vulnerability effectively neutralizes the security model that macOS employs to protect against unauthorized system modifications and data access. Organizations running affected macOS versions face significant risk of persistent malware deployment, data exfiltration, and complete system compromise. The vulnerability's exploitation can occur through various attack vectors including malicious applications, compromised software installations, or even drive-by downloads that leverage the kernel's trust in legitimate system processes. Security professionals should note that this vulnerability represents a classic example of how insufficient input validation in kernel space can create a complete system compromise scenario.
The recommended mitigation strategy involves immediate deployment of macOS Catalina 10.15.6 or later versions where Apple has implemented improved input validation controls. System administrators should also implement additional monitoring for suspicious kernel-level activities and ensure that all applications are from trusted sources. The vulnerability demonstrates the critical importance of maintaining up-to-date system patches and highlights the need for continuous security monitoring to detect potential exploitation attempts. Organizations should also consider implementing application whitelisting policies and enhanced endpoint detection capabilities to identify and prevent exploitation of similar vulnerabilities in other system components. This vulnerability serves as a reminder of the critical nature of kernel security and the potential for a single validation flaw to compromise entire system security models.