CVE-2017-13821 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.1 is affected. The issue involves the "CFString" component. It allows attackers to bypass intended memory-read restrictions via a crafted app.
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Analysis
by VulDB Data Team • 09/04/2024
The vulnerability identified as CVE-2017-13821 represents a critical memory safety issue within Apple's macOS operating system affecting versions prior to 10.13.1. This flaw resides within the Core Foundation framework's CFString component, which serves as a fundamental string handling mechanism throughout the operating system. The vulnerability stems from improper memory access controls that allow malicious applications to circumvent the intended security boundaries designed to protect system memory from unauthorized access.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where programs access memory locations beyond their allocated bounds. Attackers can exploit this weakness by crafting specially designed applications that manipulate the CFString component to perform unauthorized memory reads. The flaw essentially creates a pathway for privilege escalation where malicious code can access memory regions that should normally be restricted to system processes or protected kernel memory areas. This bypass mechanism operates at the kernel level, allowing attackers to read sensitive data that should remain protected from user-space applications.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to extract sensitive system information, potentially including cryptographic keys, user credentials, or other confidential data stored in memory. The attack vector requires the victim to install and execute a crafted application, making it a targeted vulnerability that could be delivered through malicious software or social engineering campaigns. This vulnerability significantly weakens the memory protection mechanisms that macOS employs to maintain system integrity and user privacy, potentially enabling more sophisticated attacks such as kernel exploitation or data exfiltration.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the techniques related to privilege escalation and credential access. The vulnerability enables an attacker to move laterally within a system by accessing memory that should remain protected, potentially leading to full system compromise. Organizations should immediately deploy the macOS 10.13.1 update or later versions that contain the patched CFString implementation. Additional mitigations include implementing application whitelisting policies, monitoring for unusual memory access patterns, and conducting regular security assessments to identify potentially compromised systems. The vulnerability underscores the importance of maintaining up-to-date operating system versions and highlights the critical nature of memory safety in modern operating systems where kernel-level protections must remain robust against sophisticated attack techniques.