CVE-2018-4257 in macOS
Summary
by MITRE
In macOS High Sierra before 10.13.5, a buffer overflow was addressed with improved size validation.
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Analysis
by VulDB Data Team • 04/29/2020
The vulnerability identified as CVE-2018-4257 represents a critical buffer overflow flaw discovered in macOS High Sierra versions prior to 10.13.5. This issue stems from inadequate size validation mechanisms within the operating system's kernel components, specifically affecting the handling of memory buffers during certain system operations. The flaw allows malicious actors to potentially execute arbitrary code by exploiting the insufficient bounds checking that occurs when processing user-supplied data or system inputs. The vulnerability demonstrates a classic security weakness that has been classified under CWE-121 as a stack-based buffer overflow, where insufficient validation of buffer sizes enables attackers to overwrite adjacent memory locations and potentially gain unauthorized system access. The affected system components likely involve kernel extensions or system services that process data without proper boundary checks, creating an exploitable condition that could be leveraged by threat actors to escalate privileges and compromise system integrity.
The technical implementation of this vulnerability involves the manipulation of memory allocation processes where the system fails to validate the size of incoming data before copying it into fixed-size buffers. When an attacker provides input that exceeds the allocated buffer boundaries, the excess data overflows into adjacent memory regions, potentially corrupting critical system data structures or injecting malicious code. This type of flaw typically occurs in system-level code where performance optimizations may have been prioritized over security validation, leading to scenarios where buffer operations are performed without adequate size verification. The exploitation of such vulnerabilities often requires sophisticated techniques including precise buffer overflow attacks, return-oriented programming, or other advanced exploitation methods that leverage the corrupted memory state to redirect execution flow. The specific nature of the buffer overflow in this macOS implementation suggests that it affects core system services or kernel modules that handle user input or system communications, making it particularly dangerous as it could be exploited to bypass system security controls and gain elevated privileges.
The operational impact of CVE-2018-4257 extends beyond simple privilege escalation to encompass potential system compromise and data theft capabilities for threat actors. An attacker who successfully exploits this vulnerability could gain root access to affected systems, enabling them to install malicious software, modify system files, monitor user activities, or exfiltrate sensitive information. The vulnerability affects all macOS High Sierra systems running versions earlier than 10.13.5, representing a substantial attack surface across enterprise and personal computing environments. The exploitation of such kernel-level vulnerabilities poses significant risk to organizations as it can lead to persistent backdoors, complete system compromise, and potential lateral movement within network environments. Security professionals should recognize this vulnerability as part of the broader ATT&CK framework's privilege escalation tactics, specifically targeting the use of system-level flaws to gain administrative access. The vulnerability's impact is amplified by the fact that it affects the underlying operating system kernel, making it particularly challenging to detect and remediate without proper system updates and patch management procedures.
Mitigation strategies for CVE-2018-4257 primarily focus on implementing timely security updates and maintaining comprehensive system patch management protocols. The most effective remediation involves upgrading affected macOS systems to version 10.13.5 or later, which includes the necessary size validation improvements that address the buffer overflow condition. System administrators should prioritize this update across all affected endpoints, particularly in enterprise environments where multiple macOS devices may be vulnerable. Additional protective measures include implementing network monitoring to detect anomalous behavior that might indicate exploitation attempts, deploying application whitelisting policies to prevent execution of unauthorized code, and maintaining regular security assessments of system configurations. Organizations should also consider implementing endpoint protection solutions that can detect and block exploitation attempts targeting kernel-level vulnerabilities. The vulnerability highlights the importance of maintaining current security practices including regular patch deployment, system hardening procedures, and continuous monitoring for emerging threats. Security teams should incorporate this vulnerability into their risk assessment frameworks and ensure that appropriate controls are in place to prevent exploitation attempts. The remediation process should also include verification procedures to confirm that systems have been properly updated and that the vulnerability has been fully addressed. Regular security training for system administrators and users can help prevent social engineering attacks that might attempt to exploit this vulnerability through phishing or other indirect attack vectors.