CVE-2018-4241 in iOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. tvOS before 11.4 is affected. watchOS before 4.3.1 is affected. The issue involves the "Kernel" component. A buffer overflow in mptcp_usr_connectx allows attackers to execute arbitrary code in a privileged context via a crafted app.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability identified as CVE-2018-4241 represents a critical buffer overflow flaw within the kernel component of multiple Apple operating systems including iOS, macOS, tvOS, and watchOS. This security weakness specifically affects the Multipath TCP implementation known as mptcp_usr_connectx which handles network connection establishment processes. The flaw exists in the kernel space of these operating systems, making it particularly dangerous as it allows for privilege escalation attacks that can potentially compromise the entire system. The vulnerability was present in versions prior to iOS 11.4, macOS 10.13.5, tvOS 11.4, and watchOS 4.3.1, indicating that millions of devices were potentially at risk due to this fundamental design flaw.
The technical nature of this vulnerability stems from improper bounds checking within the kernel's Multipath TCP implementation. When a crafted application attempts to establish a network connection using the mptcp_usr_connectx function, the system fails to properly validate input parameters, leading to a buffer overflow condition. This overflow occurs in kernel memory space, where attackers can manipulate memory contents to redirect execution flow. The vulnerability is classified as a buffer overflow under CWE-121, which specifically addresses stack-based buffer overflow conditions that can lead to arbitrary code execution. The flaw enables attackers to execute malicious code with kernel privileges, effectively bypassing standard user-level security restrictions and gaining full system control.
The operational impact of CVE-2018-4241 extends far beyond simple network connectivity issues, as it provides attackers with a powerful vector for system compromise. Since the vulnerability operates at the kernel level, successful exploitation can result in complete system takeover without requiring user interaction or elevated privileges. Attackers can leverage this flaw to install persistent backdoors, steal sensitive data, modify system files, or even disable security features. The attack surface is particularly concerning because the vulnerability can be triggered through legitimate applications that utilize network connectivity, making it difficult to detect and prevent. This aligns with ATT&CK technique T1055 for process injection and T1068 for exploit for privilege escalation, demonstrating how attackers can move laterally through compromised systems and maintain persistent access.
Mitigation strategies for CVE-2018-4241 primarily focus on immediate system updates and patches provided by Apple. Organizations should prioritize updating all affected devices to the latest supported versions, which include iOS 11.4, macOS 10.13.5, tvOS 11.4, and watchOS 4.3.1. Network administrators should implement monitoring solutions to detect suspicious network activity that might indicate exploitation attempts, particularly around Multipath TCP connection establishment. System hardening measures such as disabling unnecessary network services and implementing strict application whitelisting can reduce the attack surface. Additionally, security teams should conduct comprehensive vulnerability assessments to identify any potentially compromised systems and implement network segmentation to limit lateral movement if exploitation occurs. The vulnerability also underscores the importance of maintaining current security patches and following the principle of least privilege in system configurations to minimize potential impact from similar kernel-level vulnerabilities.