CVE-2011-3449 in Mac OS X
Summary
by MITRE
Use-after-free vulnerability in CoreText in Apple Mac OS X before 10.7.3 allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted embedded font in a document.
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Analysis
by VulDB Data Team • 11/29/2021
The vulnerability identified as CVE-2011-3449 represents a critical use-after-free flaw within Apple's CoreText framework, which forms a fundamental component of macOS operating systems prior to version 10.7.3. This issue manifests in the processing of embedded fonts within documents, creating a dangerous condition where memory that has been freed is subsequently accessed by malicious code. The CoreText framework is responsible for text rendering and font handling across macOS applications, making it a prime target for exploitation due to its widespread use and deep integration with the operating system's core services. The vulnerability specifically affects the way the framework manages memory allocation and deallocation when processing crafted font files, creating opportunities for attackers to manipulate memory state and execute unauthorized operations.
The technical nature of this vulnerability aligns with CWE-416, which describes use-after-free conditions where memory is accessed after it has been freed, and can be mapped to ATT&CK technique T1059.007 for process injection and T1068 for local privilege escalation. Attackers can exploit this flaw by embedding a specially crafted font within a document that, when processed by an application utilizing CoreText, triggers the use-after-free condition. The malicious font contains memory pointers that, upon being freed, are later accessed by the application's code path, allowing for arbitrary code execution or system instability. This exploit can be delivered through various document formats that support embedded fonts, including PDF documents, rich text formats, and other document types that leverage CoreText for text rendering.
The operational impact of CVE-2011-3449 extends beyond simple application crashes, as it provides attackers with the capability to execute arbitrary code with the privileges of the compromised application. This can lead to complete system compromise, particularly when the vulnerable applications have elevated privileges or when the exploitation occurs in contexts where users might be tricked into opening malicious documents. The vulnerability's remote nature means that attackers do not require physical access to the target system, making it particularly dangerous in enterprise environments where users frequently open documents from external sources. Applications that utilize CoreText for font processing, including web browsers, document viewers, and productivity suites, all represent potential attack vectors for this flaw. The vulnerability affects a broad spectrum of macOS applications that rely on CoreText for text rendering, creating a significant attack surface that could be leveraged for persistent threats.
Organizations should prioritize immediate patching of affected systems to address this vulnerability, as Apple released security updates for macOS 10.7.3 and subsequent versions that resolve the use-after-free condition. System administrators should implement strict document handling policies, particularly for documents received from external sources, and consider deploying sandboxing solutions to limit the potential impact of exploitation. Network-based mitigations such as content filtering and email scanning can help prevent the delivery of malicious documents containing crafted fonts. Additionally, monitoring for unusual application behavior or system crashes that might indicate exploitation attempts should be implemented as part of comprehensive security operations. The vulnerability demonstrates the critical importance of memory safety in system components and underscores the need for regular security updates and proactive vulnerability management to protect against sophisticated exploitation techniques.