CVE-2021-1742 in watchOS
Summary
by MITRE • 04/03/2021
This issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. Processing a maliciously crafted image may lead to arbitrary code execution.
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Analysis
by VulDB Data Team • 04/09/2021
This vulnerability represents a critical security flaw in Apple's operating systems that could enable remote code execution through image processing routines. The issue affects multiple Apple platforms including macOS Big Sur, iOS, iPadOS, watchOS, and tvOS, indicating a widespread impact across the company's ecosystem. The vulnerability stems from insufficient validation mechanisms when processing specially crafted image files, creating a pathway for malicious actors to execute arbitrary code on affected systems. This type of vulnerability falls under the category of image parsing vulnerabilities that have historically been exploited for privilege escalation and system compromise attacks.
The technical implementation of this flaw involves the image processing libraries that handle various image formats including but not limited to jpeg, png, and gif files. When these libraries encounter malformed or maliciously crafted image data, they fail to properly validate input parameters before proceeding with decompression or rendering operations. This lack of proper bounds checking and input sanitization allows attackers to craft specific image files that trigger buffer overflows, stack corruption, or other memory corruption conditions. The vulnerability is particularly concerning because it operates at the kernel level or in privileged system processes that handle image rendering, giving attackers the potential to gain elevated privileges and execute malicious payloads with system-level access. According to the CWE database, this vulnerability maps to CWE-121 which describes heap-based buffer overflow conditions, and potentially CWE-125 for out-of-bounds read errors that can occur during image parsing operations.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and data exfiltration capabilities. Attackers could potentially deploy malware, establish persistent backdoors, or perform reconnaissance activities without detection. The vulnerability's exploitation requires minimal user interaction since image files are commonly encountered through email attachments, web browsing, or file sharing applications. Security professionals should note that this vulnerability aligns with attack patterns described in the MITRE ATT&CK framework under the T1059.007 technique for command and scripting interpreter, as attackers could use the executed code to spawn shell commands or deploy additional malicious tools. The widespread adoption of affected platforms means that organizations with Apple device fleets face significant risk exposure, particularly in environments where users regularly interact with untrusted image content from external sources.
Mitigation strategies should prioritize immediate deployment of vendor security updates as outlined in the advisory. System administrators should ensure that all affected Apple devices receive the latest security patches including macOS Big Sur 11.2, Security Update 2021-001 for Catalina and Mojave, watchOS 7.3, tvOS 14.4, and iOS 14.4 with iPadOS 14.4. Network-based defenses should include image file filtering at network boundaries and email gateways to prevent malicious image attachments from reaching end users. Organizations should also implement monitoring for unusual system behavior that might indicate exploitation attempts, particularly around image processing activities. Additional defensive measures include user education about avoiding suspicious image files, disabling automatic image previews in email clients, and maintaining comprehensive backup strategies to recover from potential compromise scenarios. The vulnerability demonstrates the importance of regular security patch management and highlights the need for layered security approaches that protect against both known and zero-day exploits in widely used software platforms.