CVE-2019-8743 in watchOS
Summary
by MITRE
Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in watchOS 6.1. Processing maliciously crafted web content may lead to arbitrary code execution.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/31/2024
The vulnerability identified as CVE-2019-8743 represents a critical memory corruption flaw affecting watchOS versions prior to 6.1. This issue stems from inadequate memory handling mechanisms within the operating system's web content processing subsystem, creating potential entry points for malicious actors to execute arbitrary code on affected devices. The vulnerability specifically manifests when the system processes maliciously crafted web content, exploiting weaknesses in how memory is allocated, managed, and freed during web rendering operations. Such memory corruption vulnerabilities typically arise from buffer overflows, use-after-free conditions, or improper memory deallocation patterns that allow attackers to manipulate memory contents and gain unauthorized control over system operations. The impact of this vulnerability extends beyond simple data corruption as it enables full arbitrary code execution capabilities, potentially allowing attackers to install malicious applications, access sensitive user data, or compromise the entire device security posture.
The technical nature of this vulnerability aligns with CWE-122, which describes "Heap-based Buffer Overflow" conditions, and CWE-476, which covers "NULL Pointer Dereference" scenarios commonly found in memory corruption vulnerabilities. These weaknesses create opportunities for attackers to manipulate memory structures through crafted web content that triggers improper memory handling during content rendering. The vulnerability operates within the watchOS web processing framework, specifically targeting the memory management routines that handle HTML, CSS, and JavaScript parsing. Attackers can leverage this flaw by delivering malicious web content through various vectors including phishing websites, compromised web applications, or even embedded within legitimate web pages that users might visit. The exploitation process typically involves crafting specific content that, when rendered by the watchOS browser engine, causes memory corruption that can be leveraged to execute attacker-controlled code with the privileges of the affected application.
The operational impact of CVE-2019-8743 is particularly concerning given the widespread adoption of Apple Watch devices and their integration with users' personal and professional data. The vulnerability affects not just individual device security but also creates potential risks for enterprise environments where Apple Watch devices may be used for corporate communications, access control, or sensitive data handling. Organizations using watchOS devices for business purposes face significant exposure risks, as successful exploitation could lead to complete device compromise and potential data breaches. The vulnerability's remote exploitation capability means that attackers do not require physical access to devices, making it particularly dangerous for users who frequently access web content on their Apple Watch devices. This threat landscape is further complicated by the ATT&CK framework's T1203 technique, which describes "Exploitation for Client Execution" and demonstrates how memory corruption vulnerabilities can be leveraged for persistent access to target systems.
The mitigation strategy for CVE-2019-8743 centers exclusively on updating to watchOS 6.1 or later versions where Apple has implemented improved memory handling mechanisms. This update addresses the root cause by strengthening memory allocation and deallocation processes within the web rendering engine, implementing proper bounds checking, and adding additional validation layers to prevent the exploitation scenarios that previously led to memory corruption. Security administrators should prioritize immediate deployment of this update across all affected watchOS devices within their organization's inventory. Additional protective measures include implementing web content filtering solutions that can block known malicious domains, monitoring for suspicious web traffic patterns, and establishing incident response procedures for potential exploitation attempts. Organizations should also consider network-level protections such as firewalls that can prevent access to known malicious websites and implement mobile device management solutions that can enforce automatic update policies for all connected devices. The vulnerability serves as a reminder of the critical importance of timely security patch management, particularly for mobile operating systems where users may not regularly update their devices, and highlights the need for continuous security monitoring of mobile device environments.