CVE-2015-5944 in Mac OS X
Summary
by MITRE
CoreText in Apple OS X before 10.11.1 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted font file.
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Analysis
by VulDB Data Team • 11/18/2024
The vulnerability identified as CVE-2015-5944 represents a critical memory corruption flaw within Apple's CoreText framework affecting macOS versions prior to 10.11.1. This issue resides in the font processing subsystem that handles various font formats including TrueType, OpenType, and PostScript fonts. The vulnerability manifests when the system processes specially crafted malicious font files, leading to unpredictable behavior that can be exploited by remote attackers to gain unauthorized system access or disrupt normal operations through denial of service conditions.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within CoreText's font parsing routines. When processing malformed font data, the framework fails to properly bounds-check array accesses and validate memory allocations, creating opportunities for buffer overflows and memory corruption. This flaw aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, covering heap-based buffer overflow scenarios. The vulnerability operates at the kernel level within the graphics rendering pipeline, making it particularly dangerous as it can be triggered through various attack vectors including email attachments, web downloads, or malicious websites that serve compromised font files.
The operational impact of CVE-2015-5944 extends beyond simple exploitation capabilities to encompass significant security risks for macOS users and organizations. Attackers can leverage this vulnerability to execute arbitrary code with system-level privileges, potentially leading to complete system compromise, data exfiltration, or persistent backdoor installation. The memory corruption nature of the flaw also enables denial of service attacks that can crash applications or entire operating systems, disrupting business operations and potentially causing data loss. This vulnerability particularly affects enterprise environments where users frequently interact with untrusted content from web sources, email attachments, or collaborative documents containing embedded fonts.
Mitigation strategies for CVE-2015-5944 should prioritize immediate system updates to macOS 10.11.1 or later versions where Apple has implemented proper input validation and memory management fixes. Organizations should deploy automated patch management systems to ensure all endpoints receive security updates promptly. Network administrators can implement additional protective measures such as font filtering at network boundaries, email content scanning for suspicious font attachments, and web application firewalls that can detect and block malicious font file delivery. The vulnerability demonstrates the importance of defense-in-depth strategies as outlined in the MITRE ATT&CK framework, particularly focusing on privilege escalation and execution tactics. Security teams should also consider implementing monitoring solutions that can detect anomalous font processing activities or memory corruption patterns that might indicate exploitation attempts. Regular security assessments and penetration testing should include evaluation of font processing capabilities to identify potential vulnerabilities in custom applications or third-party software that may utilize CoreText functionality.