CVE-2018-4200 in iCloud
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.3.1 is affected. Safari before 11.1 is affected. iCloud before 7.5 on Windows is affected. iTunes before 12.7.5 on Windows is affected. tvOS before 11.4 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 that triggers a WebCore::jsElementScrollHeightGetter use-after-free.
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Analysis
by VulDB Data Team • 01/05/2025
The vulnerability identified as CVE-2018-4200 represents a critical use-after-free flaw within Apple's WebKit rendering engine that affects multiple operating systems and applications. This security issue resides in the WebCore component of WebKit and specifically targets the jsElementScrollHeightGetter function which handles JavaScript access to scroll height properties of HTML elements. The vulnerability manifests when remote attackers craft malicious web pages that trigger memory corruption through improper handling of JavaScript object references, leading to potential arbitrary code execution or system crashes. The affected products include iOS versions prior to 11.3.1, Safari versions before 11.1, iCloud for Windows versions prior to 7.5, iTunes for Windows versions before 12.7.5, and tvOS versions before 11.4, demonstrating the widespread impact across Apple's ecosystem.
The technical exploitation of this vulnerability occurs through a use-after-free condition where a JavaScript object reference becomes invalid while still being accessed by the WebCore engine. When a malicious website triggers the jsElementScrollHeightGetter function with crafted input, the underlying memory management fails to properly handle the object lifecycle, creating a scenario where freed memory can be reallocated and accessed by subsequent operations. This memory corruption vulnerability falls under CWE-416, which specifically addresses use-after-free conditions in software development. The flaw allows attackers to manipulate memory contents through carefully constructed web content, potentially enabling privilege escalation or complete system compromise. The vulnerability's impact is particularly severe because it operates at the browser level, where users frequently interact with untrusted web content, making exploitation relatively straightforward for attackers who can convince victims to visit malicious sites.
The operational impact of CVE-2018-4200 extends beyond simple application crashes to encompass potential remote code execution capabilities that could enable attackers to gain unauthorized access to affected systems. When exploited successfully, this vulnerability could allow threat actors to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise. The memory corruption nature of the flaw means that even if immediate code execution is not achieved, the instability could be leveraged to perform denial of service attacks against critical services or to create persistent backdoors. This vulnerability aligns with ATT&CK technique T1059.007, which covers the use of scripting languages for code execution, and T1203, which addresses exploitation for privilege escalation. Organizations using affected Apple products face significant risk as the vulnerability can be exploited through standard web browsing activities without requiring any special user interaction beyond visiting compromised websites.
Mitigation strategies for CVE-2018-4200 primarily focus on immediate patch deployment across all affected Apple platforms and applications. Users should prioritize updating to iOS 11.3.1, Safari 11.1, iCloud 7.5, iTunes 12.7.5, and tvOS 11.4 or later versions to address the underlying memory management issues in WebKit. Security administrators should implement network-based protections such as web application firewalls and content filtering solutions to block access to known malicious domains until full patches are deployed. Additionally, organizations should conduct comprehensive vulnerability assessments to identify any systems running affected software versions and establish monitoring procedures to detect potential exploitation attempts. The remediation process should include regular security updates, user education regarding safe browsing practices, and implementation of sandboxing measures to limit potential damage from successful exploitation attempts. System administrators should also consider implementing network segmentation to isolate critical systems from untrusted web traffic and maintain detailed logging of web browsing activities to detect anomalous behavior that might indicate exploitation attempts.