CVE-2020-9847 in macOS
Summary
by MITRE
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Catalina 10.15.5. A malicious application may be able to break out of its sandbox.
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Analysis
by VulDB Data Team • 10/20/2020
This vulnerability represents a critical sandbox escape flaw in Apple's macOS operating system that allows malicious applications to bypass security restrictions and access system resources beyond their designated boundaries. The issue stems from an insufficient bounds checking mechanism within the system's memory management subsystem, specifically affecting the sandboxing implementation that is fundamental to macOS security architecture. The vulnerability was identified as an out-of-bounds read condition where the system fails to properly validate memory access boundaries, potentially allowing crafted malicious code to read memory locations that should remain protected.
The technical nature of this flaw places it squarely within the category of memory safety vulnerabilities, which are commonly classified under CWE-129 and CWE-131 depending on the specific implementation details. The vulnerability affects the core sandboxing mechanisms that are designed to isolate applications from each other and from system resources, creating a potential pathway for privilege escalation attacks. Attackers can exploit this weakness by crafting malicious applications that leverage the out-of-bounds read to access sensitive memory regions, potentially extracting system information or manipulating protected data structures. This type of vulnerability directly impacts the security model of macOS and represents a significant risk to system integrity.
The operational impact of CVE-2020-9847 extends beyond simple data access, as it fundamentally undermines the sandboxing security model that protects users from malicious software. When exploited, this vulnerability could enable attackers to gain unauthorized access to user data, system files, and potentially escalate privileges to gain root access. The attack surface is particularly concerning because it affects applications that are designed to operate within strict sandboxed environments, making it difficult for users to predict which applications might be vulnerable. The fix implemented by Apple in macOS Catalina 10.15.5 involves enhanced bounds checking mechanisms that properly validate memory access operations and prevent unauthorized memory reads that could lead to information disclosure or system compromise.
Security professionals should note that this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and defense evasion. The sandbox escape capability makes this vulnerability particularly dangerous as it allows attackers to bypass multiple layers of security controls that are typically in place to protect system integrity. Organizations should prioritize patch management for this vulnerability, as the window of exposure for this type of sandbox escape attack can be significant. The remediation process requires careful monitoring of system updates and verification that the patch has been properly applied, as the vulnerability affects core operating system components that are essential for system security. This vulnerability serves as a reminder of the critical importance of memory safety in operating system security and the potential consequences when bounds checking mechanisms fail to properly validate system operations.