CVE-2018-4381 in tvOS
Summary
by MITRE • 10/28/2020
A resource exhaustion issue was addressed with improved input validation. This issue is fixed in tvOS 12.1, iOS 12.1. Processing a maliciously crafted message may lead to a denial of service.
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Analysis
by VulDB Data Team • 11/27/2020
The vulnerability identified as CVE-2018-4381 represents a critical resource exhaustion flaw affecting Apple's mobile operating systems. This issue manifests when the affected systems process maliciously crafted messages that trigger improper input validation mechanisms. The vulnerability resides within the core messaging processing frameworks of iOS and tvOS, where insufficient validation allows attackers to craft specially formatted inputs that consume excessive system resources during processing. The flaw specifically impacts the handling of network protocols and message parsing components that form the foundation of communication services within Apple's ecosystem. Security researchers classified this vulnerability as a denial of service condition because the malformed inputs cause the affected processes to consume disproportionate amounts of memory and processing power, ultimately leading to system instability and service interruption.
The technical implementation of this vulnerability demonstrates a classic resource exhaustion attack pattern where attacker-controlled inputs are designed to trigger iterative processing loops or memory allocation patterns that expand beyond normal operational parameters. The issue stems from inadequate bounds checking and input sanitization within the messaging subsystem, allowing malicious data to bypass standard validation procedures that would normally prevent such inputs from being processed. When the system attempts to parse these crafted messages, it enters into resource-intensive operations that can quickly deplete available memory pools, CPU cycles, and other system resources. The vulnerability is particularly concerning because it operates at a low level within the operating system stack, making it difficult to detect and isolate without comprehensive monitoring of system resource utilization patterns. This flaw aligns with CWE-400 which categorizes resource exhaustion vulnerabilities as those that allow attackers to consume system resources beyond normal operating parameters.
The operational impact of CVE-2018-4381 extends beyond simple service disruption to potentially compromise the overall stability and security posture of affected devices. In practical attack scenarios, adversaries could exploit this vulnerability to remotely force devices into denial of service states, effectively rendering them unusable until manual restart or system recovery occurs. The attack vector typically involves sending specially crafted network messages or data payloads through legitimate communication channels that the affected systems process without proper validation. This vulnerability affects a wide range of Apple devices including iPhones, iPads, and Apple TV units running the vulnerable software versions, creating significant risk for both individual users and enterprise deployments. Organizations utilizing Apple devices for critical operations face potential business disruption if attackers successfully exploit this vulnerability, particularly in environments where continuous availability is essential for operations.
Apple's resolution for this vulnerability involved implementing enhanced input validation mechanisms within the messaging processing frameworks of iOS 12.1 and tvOS 12.1. The security update introduced stricter bounds checking, improved sanitization routines, and additional resource monitoring capabilities to prevent malicious inputs from triggering resource exhaustion conditions. System administrators should prioritize deployment of these updates across all affected devices to mitigate the risk of exploitation. The mitigation strategy emphasizes the importance of maintaining current software versions and implementing network monitoring to detect unusual resource consumption patterns that might indicate exploitation attempts. Security teams should also consider implementing network segmentation and access controls to limit potential attack surface and reduce the likelihood of successful exploitation. This vulnerability demonstrates the critical importance of input validation in preventing resource exhaustion attacks and aligns with ATT&CK technique T1499 which covers resource exhaustion tactics used in denial of service scenarios. Organizations should conduct regular vulnerability assessments and maintain comprehensive incident response procedures to address similar threats that may emerge in the future.