CVE-2018-4121 in iCloud
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.3 is affected. Safari before 11.1 is affected. iCloud before 7.4 on Windows is affected. iTunes before 12.7.4 on Windows is affected. tvOS before 11.3 is affected. watchOS before 4.3 is affected. The issue involves the "WebKit" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted web site.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2018-4121 represents a critical memory corruption flaw within Apple's WebKit rendering engine that affects multiple operating systems and applications. This issue resides in the core web browsing component responsible for processing and displaying web content across Apple's ecosystem. The vulnerability specifically impacts iOS versions prior to 11.3, Safari versions before 11.1, iCloud versions before 7.4 on Windows, iTunes versions before 12.7.4 on Windows, tvOS versions before 11.3, and watchOS versions before 4.3. The flaw demonstrates the classic characteristics of a remote code execution vulnerability that can be exploited through maliciously crafted web content, making it particularly dangerous in the context of modern web browsing activities where users frequently encounter untrusted content.
The technical nature of this vulnerability stems from improper memory handling within the WebKit component that processes web page elements and JavaScript code. When a user visits a malicious website, the crafted content can trigger memory corruption conditions that allow attackers to manipulate the application's memory space. This memory corruption can manifest in two primary ways: either by enabling remote code execution where attackers can run arbitrary malicious code on the target system, or by causing denial of service conditions that result in application crashes and system instability. The vulnerability's exploitation requires no user interaction beyond visiting the malicious website, making it particularly dangerous as it can be delivered through phishing campaigns, compromised websites, or malicious advertisements.
From an operational perspective, this vulnerability creates significant security risks for Apple device users who may unknowingly encounter malicious content during normal web browsing activities. The impact extends across Apple's entire ecosystem as the same WebKit component is shared across iOS, macOS, watchOS, and tvOS platforms, meaning that a single vulnerability can affect multiple device categories simultaneously. The remote exploitation capability means that attackers can compromise systems from anywhere in the world without requiring physical access or special privileges. This vulnerability directly maps to CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions, both of which are common in memory corruption vulnerabilities. The attack surface is particularly wide as it affects the core web browsing functionality that users rely on daily.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework where it would be classified under techniques such as T1059 for command and script injection, and T1203 for exploitation for privilege escalation. The vulnerability's presence in multiple Apple products means that organizations must ensure comprehensive patch management across all affected platforms. The recommended mitigations include immediate deployment of Apple's security updates for all affected versions, implementation of web content filtering solutions, and user education regarding safe browsing practices. Additionally, network administrators should consider implementing web proxy filtering to block access to known malicious domains that may exploit this vulnerability. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches across all operating systems and applications, particularly those that handle untrusted web content. Organizations should also consider implementing monitoring solutions that can detect unusual application behavior that might indicate exploitation attempts, as the memory corruption could potentially be leveraged for more sophisticated attacks beyond simple code execution or denial of service.