CVE-2020-9949 in tvOS
Summary
by MITRE • 12/09/2020
A use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, iOS 14.0 and iPadOS 14.0, macOS Catalina 10.15.6, Security Update 2020-004 Mojave, Security Update 2020-004 High Sierra, tvOS 14.0. An application may be able to execute arbitrary code with kernel privileges.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/14/2020
This vulnerability represents a critical use-after-free condition that emerged in Apple's operating system frameworks, specifically within the kernel memory management subsystem. The flaw occurs when a program attempts to access memory that has already been freed, creating a scenario where malicious code could potentially exploit this temporal gap to manipulate system resources. Such vulnerabilities are particularly dangerous because they can be leveraged to escalate privileges from regular user-level applications to kernel-level execution, fundamentally compromising system integrity. The issue was identified as part of Apple's ongoing security hardening efforts and was addressed through enhanced memory management protocols that prevent the reuse of freed memory blocks. This particular vulnerability demonstrates the complexity of modern operating system security where memory management errors can create pathways for privilege escalation attacks.
The technical implementation of this use-after-free flaw involves improper handling of memory allocation and deallocation sequences within kernel space components. When system processes request and subsequently release memory resources, the memory management subsystem must properly track these operations to prevent reuse of freed memory regions. However, in this instance, the tracking mechanism failed to adequately prevent access to memory that had been marked for deallocation, creating a window where malicious applications could manipulate memory contents. This type of vulnerability falls under the CWE-416 category, which specifically addresses use-after-free conditions, and represents a classic example of how improper resource management can create security vulnerabilities. The attack surface is particularly concerning because it allows applications to execute code with kernel privileges, effectively bypassing the fundamental security boundaries that separate user space from kernel space operations.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and data integrity breaches. An attacker who successfully exploits this flaw could execute arbitrary code with the highest system privileges, potentially gaining complete control over affected devices. This capability enables a wide range of malicious activities including but not limited to persistent backdoor installation, data exfiltration, system monitoring, and further exploitation of other system components. The vulnerability affects multiple Apple operating systems including macOS Big Sur, watchOS, iOS, and various security update versions, indicating it was a widespread issue that required coordinated patching across the entire Apple ecosystem. From an attacker perspective, this vulnerability aligns with the ATT&CK framework's privilege escalation techniques, specifically targeting the execution of malicious code with elevated privileges through kernel-level exploitation.
Apple's response to this vulnerability involved implementing enhanced memory management controls that prevent the reuse of freed memory blocks in kernel space operations. The security updates released for affected versions include modifications to the kernel's memory allocator and improved validation mechanisms that ensure memory regions cannot be accessed after deallocation. These patches represent a defensive approach to memory safety that aligns with industry best practices for preventing use-after-free vulnerabilities. The fix demonstrates Apple's commitment to maintaining secure operating system environments through proactive vulnerability remediation and comprehensive security updates. Organizations and users should prioritize applying these security updates immediately, as the vulnerability represents a significant risk to system security and data protection. The remediation process involves not just patching the specific memory management flaw but also reinforcing the overall security posture of affected systems through proper update management practices.