CVE-2020-3847 in macOS
Summary
by MITRE
An out-of-bounds read was addressed with improved input validation. This issue is fixed in macOS Catalina 10.15.3. A remote attacker may be able to leak memory.
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Analysis
by VulDB Data Team • 04/06/2024
The vulnerability identified as CVE-2020-3847 represents a critical out-of-bounds read flaw that was discovered within the macOS operating system. This issue manifests as a memory safety vulnerability that occurs when the system processes certain inputs without adequate validation mechanisms. The flaw specifically affects macOS Catalina versions prior to 10.15.3, where the operating system's memory management routines fail to properly validate input boundaries before accessing memory locations. Such vulnerabilities typically arise from insufficient bounds checking in memory operations, allowing malicious actors to potentially access memory regions that should remain protected or inaccessible. The vulnerability is particularly concerning because it enables remote code execution capabilities through memory leakage attacks that can expose sensitive system information.
The technical implementation of this vulnerability stems from inadequate input validation procedures within the system's memory handling components. When legitimate or malicious input is processed by affected system routines, the absence of proper boundary checks allows the program to read memory locations beyond the intended buffer boundaries. This flaw aligns with CWE-129, which specifically addresses issues related to insufficient validation of the length or size of input data. The vulnerability operates at the kernel level or system service layer where memory management occurs, making it particularly dangerous as it can be exploited by remote attackers without requiring local system access. Attackers can craft specific inputs that trigger the out-of-bounds read condition, potentially causing the system to leak memory contents including sensitive data such as kernel memory addresses, cryptographic keys, or other confidential information.
The operational impact of CVE-2020-3847 extends beyond simple information disclosure, as memory leakage can provide attackers with crucial information needed for more sophisticated exploitation techniques. When remote attackers successfully exploit this vulnerability, they can potentially gather kernel memory addresses that can be used for bypassing security mitigations such as address space layout randomization. This type of information leakage can facilitate advanced persistent threat campaigns where attackers use the leaked memory information to craft more effective exploit payloads. The vulnerability's remote exploitability means that attackers do not need physical access to the target system, making it particularly dangerous for enterprise environments where macOS systems may be exposed to untrusted networks. The memory leakage can also potentially reveal system configuration details, running processes, or other sensitive operational information that can be leveraged for further reconnaissance activities.
The remediation for this vulnerability involves updating macOS systems to version 10.15.3 or later, which includes improved input validation mechanisms that prevent out-of-bounds memory access. System administrators should prioritize patching affected systems to prevent exploitation, particularly in environments where macOS systems are exposed to external networks or untrusted users. The fix implemented by Apple addresses the root cause by introducing enhanced bounds checking procedures and proper input validation before memory operations occur. Organizations should also consider implementing network monitoring solutions to detect potential exploitation attempts targeting this vulnerability. Security teams should review system logs for unusual memory access patterns or network traffic that might indicate exploitation attempts. Additionally, the vulnerability demonstrates the importance of maintaining up-to-date operating systems and implementing robust security practices that include regular patch management, network segmentation, and continuous monitoring of system behavior for signs of potential compromise. The remediation process should also include verification that systems have been properly updated and that no vulnerable components remain in the operational environment.
This vulnerability is categorized under the ATT&CK framework as a memory corruption technique, specifically related to privilege escalation and information gathering activities. The attack pattern aligns with techniques such as privilege escalation through memory corruption and credential access through information disclosure, making it a significant concern for security professionals managing macOS environments. The vulnerability's classification as an out-of-bounds read demonstrates the ongoing challenges in memory safety within modern operating systems, highlighting the need for continuous security improvements and robust input validation across all system components. Organizations should also consider implementing additional security controls such as kernel extensions monitoring, system integrity checking, and intrusion detection systems to provide defense-in-depth against similar vulnerabilities that may exist in other system components.