CVE-2017-2439 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 "FontParser" component. It allows remote attackers to obtain sensitive information or cause a denial of service (out-of-bounds read and application crash) via a crafted font file.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability identified as CVE-2017-2439 represents a critical security flaw within Apple's font processing infrastructure affecting multiple operating systems including iOS, macOS, tvOS, and watchOS. This issue resides within the FontParser component which is responsible for interpreting and rendering font files across Apple's ecosystem. The vulnerability stems from inadequate input validation and memory handling within the font parsing logic, creating a pathway for malicious actors to exploit the system through specially crafted font files. The flaw manifests as an out-of-bounds read condition that can be triggered when the system attempts to process malformed font data, leading to unpredictable behavior and potential system instability.
The technical implementation of this vulnerability demonstrates a classic buffer over-read scenario where the FontParser component fails to properly validate font file structures before attempting to access memory locations beyond the allocated buffer boundaries. This type of flaw falls under the CWE-125 vulnerability category, which specifically addresses out-of-bounds read conditions in software implementations. The vulnerability's exploitation requires minimal user interaction as it can be triggered through automated font processing when a malicious font file is encountered during normal system operations. Attackers can craft font files that contain malformed data structures designed to cause the parser to read memory locations that do not belong to the intended data structure, potentially exposing sensitive information or causing application crashes.
The operational impact of CVE-2017-2439 extends beyond simple denial of service scenarios to encompass potential information disclosure risks that could compromise system security. When exploited, the vulnerability can cause applications to crash or behave unpredictably, leading to service disruption for end users. More concerning is the potential for sensitive memory contents to be exposed through the out-of-bounds read, as attackers might be able to extract system information, credentials, or other confidential data from memory locations that should remain protected. The vulnerability affects a wide range of Apple devices and operating systems, making it particularly dangerous as it can be exploited across multiple platforms without requiring device-specific exploitation techniques. This cross-platform nature aligns with ATT&CK technique T1059.007 for Windows, though in this case it operates across Apple's ecosystem where similar exploitation patterns occur.
The remediation approach for this vulnerability requires immediate deployment of Apple's security updates, specifically iOS 10.3, macOS 10.12.4, tvOS 10.2, and watchOS 3.2, which contain patches that address the font parsing logic and implement proper bounds checking. Organizations should prioritize patch management for all affected Apple devices within their environment, as the vulnerability can be exploited remotely through various attack vectors including email attachments, web downloads, or malicious websites. Security teams should monitor for indicators of compromise related to font file processing and implement network-based detection measures to identify potentially malicious font files. The vulnerability also underscores the importance of input validation and secure coding practices, particularly in components that process untrusted data such as font files, which are commonly encountered in multimedia applications and system rendering processes.