CVE-2016-4635 in macOS
Summary
by MITRE
FaceTime in Apple iOS before 9.3.3 and OS X before 10.11.6 allows man-in-the-middle attackers to spoof relayed-call termination, and obtain sensitive audio information in opportunistic circumstances, via unspecified vectors.
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Analysis
by VulDB Data Team • 09/28/2022
The vulnerability identified as CVE-2016-4635 represents a significant security flaw in Apple's FaceTime implementation across iOS and macOS platforms. This weakness specifically affects versions prior to iOS 9.3.3 and OS X 10.11.6, creating a window of opportunity for sophisticated attackers to exploit the communication protocols used during FaceTime calls. The vulnerability stems from insufficient validation mechanisms within the FaceTime application's handling of call termination processes and audio data transmission, particularly when calls are relayed through intermediate network infrastructure.
The technical flaw manifests as a man-in-the-middle attack vector that enables adversaries to manipulate the call termination process while simultaneously intercepting audio information. This occurs through unspecified network-level vectors that allow attackers to position themselves between communicating parties and alter the communication flow. The vulnerability operates at the application layer where FaceTime relies on standard network protocols for establishing and terminating calls, but fails to implement adequate cryptographic validation or session integrity checks. Attackers can exploit this by spoofing legitimate call termination signals while maintaining access to the audio stream, effectively creating a covert channel for information extraction.
The operational impact of this vulnerability extends beyond simple eavesdropping capabilities, as it enables attackers to obtain sensitive audio information during opportunistic network interactions. This creates a persistent threat vector that can be exploited in various network environments where FaceTime communications occur, particularly in public or unsecured networks where attackers have greater opportunities to position themselves within the communication path. The vulnerability is particularly concerning because it operates in a manner that is difficult to detect from the user perspective, as the call termination appears legitimate while the audio information is being captured. This allows for prolonged surveillance operations without immediate detection by the parties involved in the communication.
Mitigation strategies for this vulnerability require immediate system updates to the patched versions of iOS and macOS, which address the underlying implementation flaws in the FaceTime application. Organizations should implement network monitoring solutions to detect anomalous communication patterns that might indicate exploitation attempts, particularly focusing on unusual call termination sequences or unexpected audio data flows. The remediation process should also include user education regarding the risks of using FaceTime in untrusted network environments and the importance of maintaining current system patches. From a security architecture perspective, this vulnerability highlights the need for robust cryptographic validation in all communication protocols and demonstrates the importance of implementing proper session management and integrity checking mechanisms. The flaw aligns with CWE-310, which addresses cryptographic weaknesses in authentication and session management, and represents a clear violation of the principle of least privilege in network communications. Organizations should also consider implementing network segmentation and encryption policies that prevent the exploitation of such vulnerabilities in enterprise environments where FaceTime communications might be subject to additional security requirements.