CVE-2021-1757 in tvOS
Summary
by MITRE • 04/03/2021
An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. A local attacker may be able to elevate their privileges.
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Analysis
by VulDB Data Team • 04/09/2021
This vulnerability represents a critical out-of-bounds read flaw that existed within Apple's operating system implementations across multiple platforms including macOS, iOS, watchOS, and tvOS. The issue stems from insufficient bounds checking mechanisms within the system's memory management operations, creating a potential pathway for malicious actors to exploit memory access violations. The vulnerability was specifically addressed through enhanced bounds checking protocols that prevent unauthorized memory access patterns. The affected versions include macOS Big Sur 11.2, Security Update 2021-001 for Catalina and Mojave, watchOS 7.3, tvOS 14.4, and iOS 14.4 along with iPadOS 14.4, indicating a widespread impact across Apple's ecosystem. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, which is classified as a common weakness in software development practices that directly relates to buffer over-read conditions.
The technical exploitation of this vulnerability allows a local attacker to potentially elevate their privileges from standard user level to administrative access within the affected systems. The out-of-bounds read condition occurs when the system attempts to access memory locations beyond the allocated buffer boundaries, which can result in information disclosure, system instability, or in this case, privilege escalation. Attackers could leverage this flaw by crafting malicious code that triggers the memory access violation, potentially allowing them to bypass system security controls and gain elevated privileges. The bounds checking improvements implemented in the security updates address the root cause by ensuring that all memory access operations are properly validated against allocated buffer limits, preventing unauthorized access to protected memory regions.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a privilege escalation vector that could enable attackers to gain full administrative control over affected devices. This poses significant risks to enterprise environments where iOS and macOS devices are commonly used for business operations, as successful exploitation could lead to complete system compromise. The vulnerability's presence across multiple Apple platforms including mobile devices, desktop operating systems, and embedded systems creates a substantial attack surface that requires immediate remediation. Organizations should consider this vulnerability as a high-priority threat that could be exploited in targeted attacks against critical infrastructure and sensitive data environments.
Security professionals should implement immediate patch management protocols to deploy the applicable security updates across all affected systems, particularly focusing on the macOS Big Sur 11.2, iOS 14.4, and watchOS 7.3 releases. The mitigation strategy should include comprehensive vulnerability scanning to identify systems running vulnerable versions and ensuring that all devices are updated to the patched releases. Additionally, organizations should monitor for potential exploitation attempts through network traffic analysis and system logs, as the privilege escalation nature of this vulnerability may generate suspicious activity patterns that align with attack techniques documented in the MITRE ATT&CK framework under privilege escalation tactics. The implementation of these security measures should be complemented by regular security awareness training for users to recognize potential social engineering attempts that might accompany such exploitation efforts.