CVE-2017-2540 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.12.5 is affected. The issue involves the "WindowServer" component. It allows attackers to bypass intended memory-read restrictions via a crafted app.
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Analysis
by VulDB Data Team • 09/02/2024
The vulnerability identified as CVE-2017-2540 represents a critical security flaw within Apple's macOS operating system affecting versions prior to 10.12.5. This vulnerability specifically targets the WindowServer component which serves as the core graphical subsystem responsible for managing display operations and window management within the macOS environment. The WindowServer component plays a fundamental role in the operating system's security architecture by enforcing memory access controls and protecting system resources from unauthorized access attempts. When compromised, this subsystem can no longer effectively maintain the integrity of memory boundaries that separate different applications and system processes, creating a significant security risk for affected systems.
The technical exploitation of this vulnerability occurs through a crafted application that manipulates the WindowServer component to bypass intended memory-read restrictions. This flaw allows malicious actors to craft applications that can access memory regions that should normally be restricted to prevent unauthorized data access. The vulnerability stems from insufficient validation mechanisms within the WindowServer's memory management routines, enabling attackers to exploit a privilege escalation path that circumvents the normal access control mechanisms. This type of vulnerability falls under the CWE-264 category of "Permissions, Privileges, and Access Controls" and represents a classic case of insufficient access control enforcement within a system's core components. The attack vector specifically targets the graphics subsystem's memory handling capabilities, where the WindowServer fails to properly validate memory access requests from applications.
The operational impact of this vulnerability extends beyond simple data theft, as it provides attackers with the capability to execute arbitrary code within the system's memory space with elevated privileges. This means that an attacker could potentially gain access to sensitive system information, manipulate running processes, or even establish persistent backdoors within the affected macOS systems. The vulnerability affects all macOS versions before 10.12.5, making it particularly dangerous as it could potentially impact a large number of devices in enterprise and personal environments. The WindowServer component's role in managing the graphical user interface makes this vulnerability especially concerning since it could be exploited through seemingly legitimate applications that appear to be harmless. This type of attack pattern aligns with ATT&CK technique T1068 which involves the exploitation of legitimate credentials or system access to gain elevated privileges.
Organizations and individual users affected by this vulnerability should immediately implement mitigation strategies to protect their systems from potential exploitation. The primary recommended action involves updating to macOS version 10.12.5 or later, which includes patches that address the memory access control flaws within the WindowServer component. System administrators should prioritize deployment of this security update across all affected macOS devices within their environment, particularly those running older versions of the operating system. Additional mitigations include implementing application whitelisting policies that restrict execution of untrusted applications, monitoring system processes for unusual memory access patterns, and maintaining comprehensive system logging to detect potential exploitation attempts. The vulnerability demonstrates the importance of maintaining current security patches and highlights the critical nature of protecting core system components that handle privileged operations. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior patterns consistent with privilege escalation attacks targeting graphics subsystems.