CVE-2010-1833 in Mac OS X
Summary
by MITRE
Apple Type Services (ATS) in Apple Mac OS X 10.6.x before 10.6.5 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted embedded font in a document.
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Analysis
by VulDB Data Team • 10/05/2021
Apple Type Services represents a critical component within macOS that handles font rendering and processing for applications and system services. This vulnerability affects Mac OS X 10.6.x versions prior to 10.6.5, specifically targeting the ATS framework's handling of embedded fonts within documents. The flaw stems from insufficient input validation and memory management when processing maliciously crafted font files that contain malformed or oversized data structures. Attackers can exploit this weakness by embedding specially constructed fonts within documents such as pdfs, word processing files, or other document formats that support embedded typography. The vulnerability manifests as a memory corruption issue that can lead to arbitrary code execution when the system attempts to render the malicious font or as a denial of service condition when the corrupted memory causes application crashes or system instability. This type of vulnerability falls under the CWE-125 vulnerability class, which describes out-of-bounds read conditions, and can be categorized under the ATT&CK technique T1059.007 for command and scripting interpreter usage. The exploitation scenario typically involves tricking a user into opening a malicious document containing the crafted font, which then triggers the vulnerable ATS component during document rendering. The memory corruption occurs at the kernel level within the font processing subsystem, making it particularly dangerous as it can potentially bypass standard user permissions and escalate privileges. The vulnerability affects not just individual applications but the entire system since ATS is a core system service that multiple applications utilize for font handling. This weakness represents a classic buffer overflow scenario where insufficient bounds checking allows attackers to overwrite adjacent memory locations, potentially leading to code execution in the context of the affected process. The impact extends beyond simple denial of service to include full system compromise when combined with additional exploitation techniques. The vulnerability is particularly concerning in enterprise environments where users may encounter malicious documents through email attachments, web downloads, or shared network resources, making it a significant threat vector for targeted attacks. Organizations should implement immediate patch management protocols to address this vulnerability, as the window for exploitation remains open for systems running affected versions of macOS.
The technical implementation of this vulnerability involves the ATS framework's failure to properly validate font file structures during parsing operations. When a document containing an embedded font is opened, the ATS component attempts to process the font metadata and rendering instructions without adequate bounds checking on the font data size or structure integrity. This lack of validation creates opportunities for attackers to craft font files that contain oversized arrays, malformed headers, or corrupted data that causes the memory allocator to behave unpredictably. The memory corruption occurs during the font processing pipeline where the system attempts to map font glyphs to memory locations, leading to potential overwrite of critical system data structures or executable code. This vulnerability demonstrates the inherent risk of complex font processing systems that must handle numerous font formats including truetype, opentype, and postscript fonts, each with their own parsing requirements and potential failure points. The flaw operates at the intersection of graphics rendering and memory management, making it particularly challenging to detect and prevent through traditional security measures. From a threat modeling perspective, this vulnerability can be leveraged as a primary attack vector in advanced persistent threat campaigns where attackers seek to establish persistent access to target systems. The vulnerability's exploitation requires minimal user interaction beyond opening a malicious document, making it suitable for phishing campaigns and social engineering attacks. Security researchers have noted that the vulnerability's impact can be amplified when combined with other memory corruption issues, potentially allowing for privilege escalation or information disclosure attacks. The ATT&CK framework categorizes this as a software exploitation technique that leverages system-level vulnerabilities to gain unauthorized access or execute malicious code. The vulnerability's presence in Apple's core system services makes it particularly difficult to isolate and secure, requiring comprehensive system-level patching rather than application-specific fixes. Organizations must ensure that all endpoints running affected macOS versions receive the necessary security updates to prevent exploitation of this critical vulnerability.