CVE-2014-4455 in iOS
Summary
by MITRE
dyld in Apple iOS before 8.1.1 and Apple TV before 7.0.2 does not properly handle overlapping segments in Mach-O executable files, which allows local users to bypass intended code-signing restrictions via a crafted file.
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Analysis
by VulDB Data Team • 03/07/2022
The vulnerability identified as CVE-2014-4455 represents a critical flaw in Apple's dynamic link editor dyld component that affects iOS versions prior to 8.1.1 and Apple TV versions prior to 7.0.2. This issue stems from improper handling of overlapping segments within Mach-O executable files, which are the standard binary format used by Apple's operating systems. The flaw exists at the core of how the system loads and processes executable code, creating a pathway for malicious actors to circumvent security mechanisms that should prevent unauthorized code execution.
The technical implementation of this vulnerability involves the manipulation of Mach-O file structures where overlapping memory segments can be crafted to exploit how dyld processes these files during loading. When the dynamic linker encounters overlapping segments, it fails to properly validate the memory layout, allowing an attacker to place malicious code in locations that would normally be restricted by code-signing policies. This behavior directly relates to CWE-129, which describes improper validation of array indices, and CWE-128, which addresses improper validation of input boundaries. The vulnerability specifically targets the memory management and loading mechanisms of the operating system, creating a condition where the security model's assumptions about memory layout are violated.
From an operational perspective, this vulnerability enables local privilege escalation attacks where an attacker with access to the device can execute arbitrary code with elevated privileges. The bypass of code-signing restrictions means that malicious applications or code modifications can be loaded without proper digital signatures, effectively undermining the entire security framework designed to prevent unauthorized software execution. This creates a significant risk for users who may unknowingly execute compromised applications, potentially leading to data theft, system compromise, or further exploitation of other vulnerabilities. The impact extends beyond individual devices to potentially affect enterprise environments where iOS devices are used for business operations.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and defense evasion. Attackers can leverage this flaw to bypass security controls that would normally prevent code execution, making it easier to establish persistent access to affected systems. The vulnerability also demonstrates the importance of proper input validation and memory management in system-level components, as highlighted by ATT&CK technique T1055 for privilege escalation through dynamic link loading. Organizations should implement immediate patch management strategies to address this vulnerability, as the window for exploitation remains open for all affected versions. The remediation approach requires updating to iOS 8.1.1 or later versions and Apple TV 7.0.2 or later, which contain the necessary patches to properly validate Mach-O segment structures and prevent the overlapping memory handling issue that enables this bypass.