CVE-2019-8549 in macOS
Summary
by MITRE
Multiple input validation issues existed in MIG generated code. These issues were addressed with improved validation. This issue is fixed in iOS 12.2, macOS Mojave 10.14.4, tvOS 12.2, watchOS 5.2. A malicious application may be able to execute arbitrary code with system privileges.
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Analysis
by VulDB Data Team • 06/10/2024
The vulnerability identified as CVE-2019-8549 represents a critical security flaw within the MIG (Mach Interface Generator) framework used in Apple's operating systems. This issue stems from inadequate input validation mechanisms within the generated code that facilitates communication between user-space applications and kernel components. The MIG framework automatically generates interface code for Mach ports, which serve as the foundation for inter-process communication in macOS and iOS environments. When input validation is insufficient, it creates pathways for malicious actors to manipulate data flows and potentially escalate privileges.
The technical nature of this vulnerability falls under CWE-20, which addresses "Improper Input Validation" and aligns with ATT&CK technique T1068, "Exploitation for Privilege Escalation." The flaw specifically manifests in the MIG-generated code where parameters passed to kernel routines are not adequately validated before processing. This creates opportunities for attackers to craft malicious inputs that can bypass normal security boundaries and execute arbitrary code with kernel-level privileges. The vulnerability is particularly dangerous because it operates at the kernel level where system integrity is paramount, allowing attackers to gain root access and potentially compromise the entire system.
The operational impact of CVE-2019-8549 extends beyond simple code execution, as it fundamentally undermines the security model of Apple's operating systems. When exploited, this vulnerability enables malicious applications to bypass the sandboxing mechanisms that normally isolate user applications from system resources. The attack surface is particularly concerning because it requires only a malicious application to be installed on the device, as opposed to more complex attack vectors requiring physical access or additional exploitation chains. This makes the vulnerability highly attractive to threat actors seeking persistent access to target systems, especially in enterprise environments where macOS and iOS devices are prevalent.
Apple addressed this vulnerability through comprehensive input validation improvements in iOS 12.2, macOS Mojave 10.14.4, tvOS 12.2, and watchOS 5.2 updates. The fix involved strengthening the validation routines within the MIG-generated code to ensure that all parameters passed to kernel interfaces are properly checked before processing. Organizations should prioritize immediate deployment of these security updates across all managed devices, particularly those handling sensitive data or operating in high-risk environments. Additional mitigations include implementing application whitelisting policies, monitoring for suspicious process behavior, and maintaining robust endpoint detection and response capabilities to identify potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of secure coding practices in system-level components and the necessity of regular security assessments of core framework elements that handle inter-process communication.