CVE-2017-13855 in watchOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.2 is affected. macOS before 10.13.2 is affected. tvOS before 11.2 is affected. watchOS before 4.2 is affected. The issue involves the "Kernel" component. It allows attackers to bypass intended memory-read restrictions via a crafted app that triggers type confusion.
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Analysis
by VulDB Data Team • 01/14/2025
The vulnerability identified as CVE-2017-13855 represents a critical kernel-level flaw affecting multiple Apple operating systems including iOS, macOS, tvOS, and watchOS. This vulnerability resides within the kernel component of Apple's operating systems, which serves as the core foundation responsible for system-level operations and memory management. The affected versions include iOS 11.1 and earlier, macOS 10.13.1 and earlier, tvOS 11.1 and earlier, and watchOS 4.1 and earlier, indicating a widespread impact across Apple's ecosystem. The vulnerability stems from a type confusion issue that fundamentally undermines the kernel's ability to properly validate data types during memory operations. Type confusion vulnerabilities occur when a program incorrectly handles data types, leading to situations where memory that should be protected becomes accessible to unauthorized processes.
The technical exploitation of this vulnerability allows attackers to bypass intended memory-read restrictions that are crucial for maintaining system security and isolation between processes. When a malicious application triggers this type confusion condition, it can manipulate the kernel's memory management routines to access memory regions that should normally be restricted to privileged system processes. This type of vulnerability falls under CWE-467, which specifically addresses "Use of sizeof() on a Pointer Type" and related type confusion issues. The attack vector requires a crafted application that can manipulate kernel memory structures through legitimate system interfaces, effectively creating a path for privilege escalation and unauthorized memory access.
The operational impact of CVE-2017-13855 extends beyond simple memory access violations as it provides attackers with the capability to bypass fundamental security mechanisms that protect system integrity. This vulnerability can enable attackers to read sensitive kernel memory, potentially accessing encryption keys, user credentials, or other confidential system information. The implications align with ATT&CK technique T1055, which covers "Process Injection" and related privilege escalation methods, as the vulnerability allows for unauthorized access to kernel memory spaces that should remain protected. The vulnerability also represents a significant risk for maintaining system confidentiality and integrity, as it allows attackers to potentially escalate privileges and gain deeper access to system resources than intended by the operating system's security model.
Apple addressed this vulnerability through security updates that corrected the type confusion issue within the kernel memory management subsystem. The mitigation strategy involved strengthening type validation mechanisms and improving memory access controls to prevent unauthorized memory reads. Organizations should prioritize applying the relevant security patches for iOS 11.2, macOS 10.13.2, tvOS 11.2, and watchOS 4.2 to ensure protection against this vulnerability. Security professionals should monitor for indicators of compromise related to unauthorized memory access attempts and implement additional monitoring for suspicious kernel-level activities. The vulnerability demonstrates the critical importance of kernel security in operating system design and highlights the necessity of rigorous type checking and memory validation mechanisms to prevent privilege escalation attacks that could compromise entire operating system ecosystems.