CVE-2016-7639 in iCloud
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 10.2 is affected. Safari before 10.0.2 is affected. iCloud before 6.1 is affected. iTunes before 12.5.4 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.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-7639 represents a critical memory corruption flaw within Apple's WebKit rendering engine that affected multiple iOS and macOS products. This vulnerability specifically targets the WebKit component which serves as the core web browsing engine powering Safari and other Apple applications. The flaw manifests as a heap-based buffer overflow that occurs during the processing of malformed web content, creating a dangerous attack surface for remote threat actors. The affected versions include iOS before 10.2, Safari before 10.0.2, iCloud before 6.1, and iTunes before 12.5.4, indicating a widespread impact across Apple's ecosystem. The vulnerability's classification aligns with CWE-121, heap-based buffer overflow, which is a well-documented weakness in software security where data written to heap memory exceeds allocated buffer boundaries. This particular flaw demonstrates how WebKit's JavaScript engine and HTML parsing components can be manipulated to trigger memory corruption through carefully crafted web pages.
The technical exploitation of this vulnerability enables attackers to execute arbitrary code on affected systems with the privileges of the compromised application. When users navigate to a maliciously crafted website, the WebKit engine processes the malformed content and triggers a memory corruption condition that can be leveraged for privilege escalation or complete system compromise. The memory corruption manifests as either an application crash or more dangerously, allows for code execution through controlled memory manipulation. This type of vulnerability falls under the ATT&CK framework's technique T1059.007 for Command and Scripting Interpreter, as attackers can use the code execution capability to run malicious payloads. The vulnerability's impact extends beyond simple denial of service, as it provides attackers with the ability to bypass security mechanisms and potentially gain persistent access to affected devices. The attack vector is particularly dangerous because it requires no user interaction beyond visiting a malicious website, making it a prime target for drive-by download attacks and phishing campaigns.
The operational impact of CVE-2016-7639 is substantial given the widespread adoption of affected Apple products and the privilege escalation capabilities it provides. Organizations and individual users running vulnerable versions of iOS, Safari, iCloud, or iTunes face significant risk of compromise, particularly in environments where these applications are frequently used for web browsing and file synchronization. The vulnerability's exploitation can lead to complete system compromise, data theft, and persistent backdoor access. Security teams must understand that this vulnerability operates at the kernel level within the WebKit engine, making it particularly challenging to detect and mitigate. The flaw's presence in multiple Apple applications creates a cascading risk where compromise of one application could potentially lead to broader system infiltration. Organizations should recognize that this vulnerability aligns with ATT&CK technique T1068, Exploitation for Privilege Escalation, and T1190, Exploit Public-Facing Application, as it represents a remote exploitation vector targeting publicly accessible web applications. The vulnerability's memory corruption nature also makes it susceptible to advanced exploitation techniques including return-oriented programming and heap spraying methods.
Mitigation strategies for CVE-2016-7639 must prioritize immediate patch deployment across all affected Apple products, with particular attention to iOS devices and Safari installations. System administrators should implement network-based protections including web proxies and content filtering solutions that can block malicious websites before they reach vulnerable systems. The recommended approach involves updating to iOS 10.2, Safari 10.0.2, iCloud 6.1, and iTunes 12.5.4, which contain the necessary security patches. Organizations should also consider implementing browser hardening measures such as disabling JavaScript for untrusted sites, using sandboxed browsing environments, and maintaining strict network segmentation to limit potential lateral movement. Security monitoring should include detection of unusual memory allocation patterns and application crashes that could indicate exploitation attempts. The vulnerability's classification as a heap-based buffer overflow necessitates memory protection mechanisms including stack canaries, address space layout randomization, and data execution prevention. Regular security assessments should verify that all endpoints are updated and that no vulnerable applications remain in use. Given the vulnerability's potential for privilege escalation, organizations should also implement comprehensive incident response procedures to detect and respond to potential exploitation attempts, including monitoring for unauthorized access patterns and suspicious file modifications.