CVE-2011-0229 in Mac OS X
Summary
by MITRE
Apple Type Services (ATS) in Apple Mac OS X through 10.6.8 does not properly handle embedded Type 1 fonts, which allows remote attackers to execute arbitrary code via a crafted document that triggers an out-of-bounds memory access.
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Analysis
by VulDB Data Team • 11/23/2021
Apple Type Services represents a critical component within macOS that manages font rendering and processing for various applications and system functions. The vulnerability exists in the handling of Type 1 font formats, which are legacy font standards that have been superseded by more modern font technologies. This flaw specifically affects Mac OS X versions through 10.6.8, indicating a long-standing issue that persisted across multiple system releases. The vulnerability stems from inadequate input validation and memory management within the ATS framework when processing malformed Type 1 font data embedded within documents. This represents a classic buffer overflow condition where attacker-controlled data can cause memory corruption beyond intended boundaries.
The technical implementation of this vulnerability allows remote attackers to craft malicious documents containing specially formatted Type 1 fonts that trigger out-of-bounds memory access during font processing. When the system attempts to render these fonts, the ATS component fails to properly validate font structure parameters, leading to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected application. This flaw operates at the intersection of font processing and memory management, creating a pathway for code execution through document rendering. The vulnerability's remote exploitability means that simply opening or previewing a malicious document can trigger the attack vector, making it particularly dangerous in email attachments or web-based content scenarios.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise and data theft. Since ATS is deeply integrated into macOS font handling, the attack surface includes virtually all applications that render text, from word processors to web browsers to email clients. The out-of-bounds memory access can lead to various outcomes including application crashes, privilege escalation, or complete system compromise depending on the exploitation method. This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a significant weakness in the system's memory safety mechanisms. The attack pattern follows typical remote code execution methodologies described in the MITRE ATT&CK framework under T1203 for Exploitation for Client Execution, demonstrating how legacy font processing can become a vector for modern exploitation techniques.
Mitigation strategies for this vulnerability require immediate system updates and patches from Apple, as the flaw exists in core system components that cannot be easily circumvented through application-level controls. Organizations should implement strict document filtering policies that prevent execution of potentially malicious documents containing embedded fonts, particularly from untrusted sources. System administrators should consider disabling font embedding in applications where possible and monitor for unusual memory access patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date system components and demonstrates how legacy code in system services can create persistent security risks. Security monitoring should focus on font processing activities and memory corruption indicators, while user education regarding suspicious document attachments remains crucial for preventing successful exploitation attempts.