CVE-2016-8507 in Browser for iOS
Summary
by MITRE
Yandex Browser for iOS before 16.10.0.2357 does not properly restrict processing of facetime:// URLs, which allows remote attackers to initiate facetime-call without user's approval and obtain video and audio data from a device via a crafted web site.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2016-8507 affects Yandex Browser for iOS versions prior to 16.10.0.2357, representing a significant security flaw in mobile browser implementation that undermines user privacy and device security. This issue stems from improper handling of facetime:// URLs within the browser's URL processing mechanism, creating an exploitable vector that allows remote attackers to bypass normal user consent requirements. The flaw specifically targets the iOS operating system's FaceTime functionality, which is designed to require explicit user approval before initiating video or audio calls. When a malicious website crafts a facetime:// URL and presents it to a vulnerable Yandex Browser instance, the browser fails to properly validate or restrict the URL processing, enabling automatic execution of FaceTime calls without user interaction. This represents a direct violation of the principle of least privilege and user consent in mobile security architectures.
The technical implementation of this vulnerability involves the browser's failure to properly sanitize or validate external URL schemes that interface with system-level applications. According to CWE-20, this vulnerability maps to improper input validation, where the browser fails to properly validate the facetime:// URL scheme before processing it. The flaw demonstrates a classic case of insufficient restriction of URL schemes, where the browser should have implemented proper checks to prevent automatic execution of system-level calls. The vulnerability operates through the iOS URL scheme handling mechanism, where the browser's lack of proper validation allows crafted URLs to trigger system-level FaceTime functionality. This issue aligns with ATT&CK technique T1059.007, which describes the use of URL schemes to execute system commands or initiate privileged operations without user awareness. The vulnerability's exploitation requires no local privileges and can be initiated entirely through a web-based attack vector, making it particularly dangerous in mobile environments where users frequently browse untrusted websites.
The operational impact of this vulnerability extends beyond simple privacy violations to encompass potential security breaches and unauthorized access to sensitive device resources. Attackers can leverage this flaw to conduct unauthorized surveillance by automatically initiating FaceTime calls, potentially capturing video and audio data without the user's knowledge or consent. This capability creates opportunities for malicious actors to perform reconnaissance, gather intelligence, or conduct surveillance operations against targeted individuals. The vulnerability affects all users of the affected Yandex Browser versions, regardless of their security awareness or device configuration, as the exploitation occurs entirely within the browser's URL processing logic. The automatic nature of the attack means that users cannot easily detect or prevent the unauthorized FaceTime initiation, as it occurs without any visible user interaction or system prompts. This represents a significant threat to personal privacy and could potentially be exploited for more sophisticated attacks involving social engineering or data exfiltration.
Mitigation strategies for this vulnerability focus on both immediate remediation and long-term architectural improvements. The primary solution involves updating to Yandex Browser version 16.10.0.2357 or later, which includes proper URL scheme validation and restriction mechanisms. Organizations should implement browser security policies that restrict the execution of potentially dangerous URL schemes and maintain regular update schedules to address known vulnerabilities. System administrators should consider implementing network-level controls to block or monitor facetime:// URL traffic, though this approach may not fully address the browser-based exploitation. The vulnerability highlights the importance of proper input validation and URL scheme handling in mobile browser implementations, as outlined in security best practices for mobile application development. Additionally, users should be educated about the risks of visiting untrusted websites and the importance of keeping their browser software updated. Security frameworks such as the OWASP Mobile Security Project emphasize the need for proper URL handling and input validation in mobile applications, making this vulnerability a prime example of why such practices are essential in mobile security architecture.