CVE-2020-27922 in tvOS
Summary
by MITRE • 04/03/2021
A logic issue was addressed with improved state management. This issue is fixed in macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave, macOS Big Sur 11.0.1, iOS 14.2 and iPadOS 14.2, watchOS 7.1, tvOS 14.2. Processing a maliciously crafted font file may lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 04/08/2021
The vulnerability identified as CVE-2020-27922 represents a critical logic flaw in Apple's font processing subsystem that was addressed through enhanced state management controls. This issue specifically affects the handling of maliciously crafted font files within Apple's operating systems, creating a potential pathway for arbitrary code execution that could be exploited by threat actors. The vulnerability stems from insufficient validation mechanisms during font file parsing operations, allowing attackers to craft specially designed font files that could trigger unexpected behavior in the system's rendering engine.
The technical nature of this vulnerability aligns with CWE-254, which encompasses security weaknesses related to inadequate input validation and improper state handling. When the system processes these malicious font files, the flawed state management allows for improper memory handling and execution flow manipulation. The vulnerability operates at the intersection of font rendering engines and system security boundaries, where the normal processing flow becomes compromised. This type of flaw typically manifests when the application fails to properly validate or sanitize input data before processing, leading to potential exploitation through buffer overflows, memory corruption, or execution hijacking mechanisms.
The operational impact of CVE-2020-27922 extends across multiple Apple platforms including macOS Big Sur, iOS, watchOS, and tvOS, creating a widespread attack surface that threat actors could leverage. The vulnerability's exploitation potential is particularly concerning given that font files are commonly encountered in various digital contexts including web browsing, document viewing, and email attachments. Attackers could potentially deliver malicious payloads through seemingly benign font files embedded in documents, websites, or email attachments, making this vector particularly stealthy and difficult to detect. The arbitrary code execution capability provides attackers with complete system compromise potential, allowing for privilege escalation, data exfiltration, and persistent access.
The remediation for this vulnerability required Apple to implement enhanced state management protocols within their font processing frameworks, specifically addressing the improper handling of font file structures during rendering operations. The security updates released for macOS Big Sur 11.1, iOS 14.2, and other affected versions include patches that strengthen input validation, improve memory management during font parsing, and implement additional safeguards against malformed font data. These mitigations align with ATT&CK technique T1059.007, which covers the use of scripting languages for execution, as the vulnerability could enable attackers to execute arbitrary code through the compromised font processing subsystem. Organizations should prioritize deployment of these updates across all affected systems to prevent exploitation attempts and maintain operational security posture against this specific threat vector.