CVE-2017-2435 in tvOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 10.3 is affected. macOS before 10.12.4 is affected. tvOS before 10.2 is affected. watchOS before 3.2 is affected. The issue involves the "CoreText" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted font file.
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Analysis
by VulDB Data Team • 10/27/2024
The vulnerability identified as CVE-2017-2435 represents a critical memory corruption flaw within Apple's CoreText framework that affects multiple operating systems including iOS, macOS, tvOS, and watchOS. This vulnerability resides in the font processing subsystem where the CoreText component fails to properly validate font files before parsing them, creating a potential attack vector for remote code execution. The flaw specifically manifests when the system processes crafted font files that contain malformed data structures designed to trigger memory corruption during parsing operations.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations. Attackers can exploit this weakness by delivering malicious font files through various attack vectors including email attachments, web downloads, or malicious websites that automatically render fonts in applications. When affected systems attempt to process these specially crafted fonts, the CoreText framework encounters corrupted memory structures that can lead to unpredictable behavior including arbitrary code execution or system crashes. The memory corruption occurs during font rendering operations where the framework fails to properly bounds-check array accesses or validate data structures within the font file format.
The operational impact of CVE-2017-2435 extends across Apple's entire ecosystem of devices and applications that rely on CoreText for font rendering. This includes not only the primary operating systems but also applications that utilize the CoreText framework for text processing and display. The vulnerability's remote exploitability means that attackers do not require physical access to devices or local network privileges to carry out successful attacks. The potential for denial of service combined with arbitrary code execution makes this a particularly dangerous vulnerability that could be leveraged for more sophisticated attacks. Organizations and individual users face significant risk as the vulnerability affects widely deployed software versions, making it a prime target for nation-state actors and cybercriminals seeking to compromise Apple devices at scale.
Mitigation strategies for this vulnerability require immediate patching of affected systems through official Apple updates. Users should ensure their iOS, macOS, tvOS, and watchOS devices are updated to versions 10.3, 10.12.4, 10.2, and 3.2 respectively, which contain the necessary fixes for the CoreText memory corruption issue. System administrators should implement proactive monitoring for any attempts to access or process untrusted font files, particularly in enterprise environments where device management is critical. Network security controls including web filtering and email scanning should be enhanced to prevent automatic font rendering of suspicious content. The vulnerability also highlights the importance of input validation and proper memory management practices in font processing libraries, as outlined in the software security principles of the OWASP Top Ten and the CERT/CC secure coding guidelines. Organizations should consider implementing application whitelisting and sandboxing measures to limit the impact of potential exploitation attempts. Additionally, regular security assessments of font handling capabilities and comprehensive incident response procedures should be established to address similar vulnerabilities that may arise in the future.