CVE-2015-3758 in iOS
Summary
by MITRE
UIKit WebView in Apple iOS before 8.4.1 allows attackers to bypass an intended user-confirmation requirement and initiate arbitrary FaceTime calls via an app that provides a crafted URL.
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Analysis
by VulDB Data Team • 06/10/2022
The vulnerability CVE-2015-3758 represents a critical security flaw in Apple iOS WebView components that affected versions prior to 8.4.1. This issue resides within the UIKit framework's handling of web content and specifically impacts how FaceTime calls are initiated through web-based interfaces. The flaw enables malicious actors to exploit a bypass mechanism that circumvents the expected user confirmation process that should normally occur before any FaceTime initiation. This represents a significant degradation in Apple's security model for user consent and privacy protection.
The technical implementation of this vulnerability stems from improper validation of FaceTime URL schemes within the iOS WebView component. When an application presents a crafted URL that triggers a FaceTime call, the system fails to properly enforce the user confirmation dialog that should appear before any network activity is initiated. This occurs because the WebView component does not adequately distinguish between legitimate user-initiated requests and automated malicious triggers. The flaw essentially allows an attacker to construct a specially formatted URL that, when processed by the WebView, automatically initiates a FaceTime session without requiring explicit user interaction. This behavior violates fundamental security principles of user consent and privilege escalation.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential security breaches and unauthorized communications. Attackers could leverage this flaw to initiate FaceTime calls to arbitrary phone numbers or email addresses without user knowledge or consent, potentially leading to unwanted communication, social engineering attacks, or even phishing attempts where victims might unknowingly engage in FaceTime sessions with malicious actors. The vulnerability could be exploited through various attack vectors including malicious websites, phishing emails, or compromised applications that embed the crafted URLs within their content. This represents a direct violation of Apple's security model and could be used to establish persistent communication channels or gather information through audiovisual means without user awareness.
Mitigation strategies for CVE-2015-3758 primarily involve updating to iOS 8.4.1 or later versions where Apple implemented proper validation mechanisms for FaceTime URL handling. Organizations should ensure all iOS devices within their environment receive timely security updates to prevent exploitation. Network administrators should monitor for suspicious web traffic patterns and consider implementing web content filtering solutions that can detect and block malicious FaceTime URL schemes. Additionally, user education programs should emphasize the importance of verifying application sources and avoiding untrusted websites that might contain malicious content designed to exploit this vulnerability. The flaw aligns with CWE-601 URL Redirection to Untrusted Site vulnerability pattern and could be categorized under ATT&CK technique T1190 for Exploit Public-Facing Application, representing a classic case of improper input validation leading to privilege escalation through user interface bypass mechanisms.