CVE-2018-4120 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. 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 • 02/08/2021
The vulnerability identified as CVE-2018-4120 represents a critical memory corruption flaw within Apple's WebKit rendering engine that affects multiple operating systems and applications. This vulnerability specifically targets the WebKit component which serves as the foundation for Safari web browser and other Apple applications that utilize web content rendering. The flaw exists in iOS versions prior to 11.3, Safari versions prior to 11.1, iCloud for Windows versions prior to 7.4, iTunes for Windows versions prior to 12.7.4, and tvOS versions prior to 11.3, indicating a widespread impact across Apple's ecosystem. The vulnerability stems from improper memory management within the WebKit engine when processing maliciously crafted web content, creating opportunities for attackers to exploit memory corruption issues that can lead to arbitrary code execution or application crashes.
The technical nature of this vulnerability aligns with CWE-125, which describes "Out-of-bounds Read" conditions that can result in memory corruption and potentially arbitrary code execution. Attackers can leverage this flaw by hosting malicious web content on compromised websites that, when loaded in affected Apple applications, trigger the memory corruption. The exploitation mechanism typically involves crafting specific web pages with malformed content that causes the WebKit engine to improperly handle memory allocation and deallocation, leading to buffer overflows or use-after-free conditions. When users navigate to these malicious sites through Safari or other affected applications, the WebKit engine processes the content in a way that corrupts memory structures, potentially allowing remote attackers to execute arbitrary code with the privileges of the affected application.
The operational impact of CVE-2018-4120 extends beyond simple application instability, as it presents a significant security risk that can be exploited for full system compromise. The vulnerability enables remote code execution, meaning attackers can gain unauthorized access to affected systems without requiring physical access or user interaction beyond visiting a malicious website. This makes the vulnerability particularly dangerous in targeted attack scenarios where threat actors can craft convincing phishing campaigns or leverage compromised websites to deliver malware. The memory corruption aspect also means that applications can crash unpredictably, creating denial of service conditions that can disrupt legitimate user activities while potentially providing attackers with additional opportunities to refine their exploitation techniques. The widespread nature of affected applications increases the attack surface significantly, as users may encounter malicious content through various entry points including web browsing, email attachments, or compromised websites.
Organizations and users should immediately apply the security patches released by Apple to address this vulnerability, particularly focusing on updating iOS, Safari, iCloud, iTunes, and tvOS to their latest versions. System administrators should implement network monitoring to detect potential exploitation attempts and consider deploying web content filtering solutions that can block known malicious domains. The mitigation strategy should include comprehensive patch management processes to ensure all affected Apple applications and operating systems are updated promptly. Additionally, user education regarding the dangers of visiting untrusted websites and the importance of keeping software updated remains crucial in preventing exploitation. Security teams should also monitor for indicators of compromise related to this vulnerability and consider implementing sandboxing techniques for web browsing activities to limit potential damage from successful exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and the potential consequences of running outdated software in enterprise and personal computing environments.