CVE-2016-4623 in tvOS
Summary
by MITRE
WebKit in Apple iOS before 9.3.3, Safari before 9.1.2, and tvOS before 9.2.2 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, a different vulnerability than CVE-2016-4589, CVE-2016-4622, and CVE-2016-4624.
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Analysis
by VulDB Data Team • 09/06/2022
This vulnerability exists within the WebKit rendering engine used by Apple's iOS, Safari, and tvOS platforms, representing a critical memory corruption flaw that enables remote code execution. The issue affects versions prior to iOS 9.3.3, Safari 9.1.2, and tvOS 9.2.2, where improper handling of crafted web content can lead to arbitrary code execution or denial of service conditions. The vulnerability stems from insufficient input validation and memory management within WebKit's JavaScript engine, specifically in how it processes certain web page elements and objects. Attackers can exploit this by hosting malicious web content that, when loaded in a vulnerable browser, triggers memory corruption through improper memory allocation, deallocation, or pointer manipulation. The flaw operates at the intersection of multiple attack vectors including heap-based buffer overflows, use-after-free conditions, and memory corruption patterns that have been classified under common weakness enumeration CWE-125 for out-of-bounds read errors and CWE-787 for out-of-bounds write errors. This vulnerability aligns with tactics described in the attack pattern taxonomy where adversaries leverage browser-based exploits to establish initial access points. The operational impact of this vulnerability extends beyond simple code execution to include complete system compromise, as successful exploitation allows attackers to execute arbitrary commands with the privileges of the affected browser process. The memory corruption occurs during normal web page rendering operations when processing maliciously crafted HTML, JavaScript, or CSS elements that trigger improper memory handling within WebKit's internal structures. This type of vulnerability represents a significant concern for enterprise environments where users may inadvertently visit compromised websites, and for threat actors seeking persistent access through browser-based attack chains. The exploitability of this vulnerability is enhanced by the fact that it does not require user interaction beyond visiting a malicious website, making it particularly dangerous for widespread deployment. Security researchers have noted that such memory corruption vulnerabilities often serve as initial access vectors for more sophisticated attack chains, where the initial code execution leads to privilege escalation and further system compromise. The vulnerability's classification under attack techniques such as T1203 for Exploitation for Client Execution and T1059 for Command and Scripting Interpreter demonstrates its potential for broader attack surface exploitation. Organizations should consider implementing network-based protections such as web application firewalls and content filtering solutions alongside immediate patch deployment to mitigate the risk. The remediation approach requires updating to patched versions of the affected Apple operating systems, which include memory safety improvements and enhanced input validation mechanisms. Additionally, browser hardening techniques including sandboxing, memory protection, and strict content security policies should be implemented to reduce the potential impact of similar future vulnerabilities. The vulnerability highlights the importance of maintaining up-to-date browser security patches and demonstrates how rendering engine flaws can provide attackers with powerful exploitation capabilities.