CVE-2020-9966 in iOS
Summary
by MITRE • 12/09/2020
An out-of-bounds read was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0. An application may be able to execute arbitrary code with kernel privileges.
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Analysis
by VulDB Data Team • 12/14/2020
This vulnerability represents a critical out-of-bounds read flaw that existed within Apple's operating system kernel components, specifically affecting devices running iOS 14.0, iPadOS 14.0, macOS Big Sur 11.0.1, watchOS 7.0, and tvOS 14.0. The issue stems from insufficient input validation mechanisms within kernel-level processes that handle system calls or data processing operations. Such vulnerabilities typically arise when software fails to properly validate the boundaries of memory access operations, allowing malicious code to read data beyond allocated memory regions. The vulnerability is classified under CWE-129 as an insufficient input validation issue, which directly relates to improper validation of input data that can lead to memory corruption and privilege escalation attacks. From an operational perspective, this flaw represents a severe security weakness because it enables an application to execute arbitrary code with kernel privileges, effectively granting the malicious software the highest level of system access possible. The implications extend beyond simple data theft or system disruption, as kernel-level privilege escalation allows attackers to bypass all standard security controls, modify system files, install persistent backdoors, and potentially compromise the entire device. This vulnerability aligns with ATT&CK technique T1068 which describes the use of local privilege escalation to gain root or system-level access to compromised systems. The attack surface for this vulnerability encompasses any application that interacts with kernel services or system APIs, making it particularly dangerous as it could be exploited through seemingly benign applications that appear legitimate to users.
The technical exploitation of this vulnerability requires an attacker to craft malicious input that triggers the out-of-bounds read condition during kernel processing. When an application provides malformed or oversized input to a kernel function, the system's memory management routines may not properly bounds-check the data, allowing the program to access memory locations that should be protected. This can result in information disclosure, system instability, or more critically, code execution with elevated privileges. The fix implemented by Apple involved strengthening input validation mechanisms within the kernel components, ensuring that all data processed by system services undergoes proper boundary checking before memory access operations are performed. This represents a classic example of how insufficient input validation can lead to privilege escalation attacks, as detailed in the CWE taxonomy and commonly observed in advanced persistent threat campaigns. The vulnerability's impact is particularly severe because it affects core operating system components that are fundamental to system security and integrity. Devices running the affected versions of Apple's operating systems are vulnerable to attacks that can result in complete system compromise, making this a critical security issue that requires immediate remediation. The mitigation strategy involves updating to the patched versions of the affected operating systems, which include enhanced validation routines and improved memory management controls that prevent the out-of-bounds read conditions from occurring. Organizations should prioritize deployment of these security updates across all affected devices, as the vulnerability represents a significant risk to enterprise security infrastructure where Apple devices are commonly used. The fix demonstrates Apple's commitment to addressing kernel-level security issues through proactive patch management and improved code validation practices.