CVE-2015-5907 in iOS
Summary
by MITRE
WebKit in Apple iOS before 9 allows man-in-the-middle attackers to conduct redirection attacks by leveraging the mishandling of the resource cache of an SSL web site with an invalid X.509 certificate.
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Analysis
by VulDB Data Team • 06/16/2022
The vulnerability identified as CVE-2015-5907 represents a critical security flaw in Apple iOS versions prior to 9.0, specifically within the WebKit rendering engine that handles web content. This issue stems from improper handling of SSL certificate validation within the browser's resource caching mechanism, creating a significant attack vector for man-in-the-middle adversaries who can exploit this weakness to manipulate web traffic redirection. The vulnerability operates by exploiting the way iOS WebKit processes cached resources from websites that present invalid X.509 certificates, allowing attackers to intercept and redirect user requests without proper certificate validation.
The technical implementation of this vulnerability involves the WebKit engine's cache management system failing to properly validate SSL certificates when storing and retrieving cached resources. When a website presents an invalid X.509 certificate, the browser should reject the connection or at least warn the user about the security risk. However, in affected iOS versions, the caching mechanism continues to store and serve cached content from these insecure sites, effectively bypassing certificate validation for subsequent requests. This behavior creates a window of opportunity for attackers to perform SSL stripping attacks or redirect users to malicious sites while maintaining the appearance of a legitimate connection.
From an operational perspective, this vulnerability significantly impacts user security and privacy by enabling attackers to conduct sophisticated redirection attacks without detection. The man-in-the-middle attack scenario becomes particularly dangerous because users may not realize they are being redirected to malicious sites, especially when the cached content appears legitimate. The vulnerability affects all web browsing activities on affected iOS versions, making it a widespread concern that could compromise sensitive data transfers, authentication processes, and overall user trust in web applications. This weakness particularly impacts enterprise users and individuals who rely on iOS devices for secure online transactions and communications.
Security professionals should consider this vulnerability in relation to CWE-295 which addresses improper certificate validation, and the MITRE ATT&CK framework's T1573.002 technique for "Tunneling through a web service" which describes how attackers can manipulate web traffic to achieve their objectives. The vulnerability demonstrates how cache poisoning techniques can be leveraged to bypass fundamental security controls that should prevent insecure connections from being cached and reused. Organizations should implement immediate mitigations including updating iOS devices to version 9.0 or later, implementing additional network monitoring for suspicious redirection patterns, and educating users about recognizing potential security warnings. The fix in iOS 9.0 addressed the core issue by implementing stricter certificate validation procedures within the WebKit cache management system, ensuring that resources from sites with invalid certificates are not cached or served to users in subsequent connections.