CVE-2015-1093 in Watch OS
Summary
by MITRE
FontParser in Apple iOS before 8.3 and Apple OS X before 10.10.3 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 • 11/30/2024
The vulnerability identified as CVE-2015-1093 represents a critical memory corruption flaw within Apple's FontParser component that affected iOS versions prior to 8.3 and OS X versions prior to 10.10.3. This vulnerability resides in the core font processing functionality that handles various font file formats including TrueType, OpenType, and other embedded font types used throughout Apple's operating systems. The flaw manifests when the system processes malformed or specially crafted font files, leading to unpredictable memory behavior that can be exploited by remote attackers to gain arbitrary code execution privileges or induce system crashes through denial of service conditions.
The technical implementation of this vulnerability stems from insufficient input validation and memory management within the FontParser subsystem. When a malicious font file is processed, the parser fails to properly validate the font structure and header information, allowing attackers to craft specific byte sequences that trigger buffer overflows or memory corruption patterns. This type of vulnerability falls under the CWE-125 weakness category, which describes out-of-bounds read conditions, and is particularly dangerous because it operates at a low system level where font rendering occurs automatically during application launches or document processing. The vulnerability is classified as a remote code execution flaw because attackers can deliver malicious font files through various attack vectors including email attachments, web pages, or file sharing services without requiring user interaction beyond normal system operations.
The operational impact of CVE-2015-1093 extends beyond simple system instability to encompass full system compromise capabilities for skilled attackers. When successfully exploited, the vulnerability allows remote attackers to execute arbitrary code with the privileges of the affected application, typically resulting in complete system control. This makes it particularly dangerous in enterprise environments where users may inadvertently open malicious documents or visit compromised websites. The vulnerability is especially concerning because font processing occurs frequently during normal system operations, making exploitation opportunities abundant and difficult to predict or prevent. Attackers can leverage this flaw through various attack patterns that align with the ATT&CK framework's T1203 technique for exploitation of remote services, potentially using the vulnerability to establish persistent backdoors or escalate privileges within affected systems.
Mitigation strategies for this vulnerability require immediate patch application as the primary defense mechanism, with Apple releasing security updates for iOS 8.3 and OS X 10.10.3 that address the underlying memory corruption issues in FontParser. System administrators should implement proactive monitoring for suspicious font file handling activities and consider network-level restrictions on font file types where possible. Organizations should also deploy endpoint protection solutions that can detect and block malicious font file processing attempts, while maintaining regular security assessments to identify systems running vulnerable versions. The vulnerability serves as a reminder of the critical importance of font security in operating systems, as font processing represents one of the most common attack surfaces for privilege escalation exploits. Additionally, implementing principle of least privilege configurations and regular system updates can significantly reduce the risk of exploitation, while security awareness training can help users recognize potential phishing attempts that may deliver malicious font files.