CVE-2015-5892 in iOS
Summary
by MITRE
Siri in Apple iOS before 9 allows physically proximate attackers to bypass an intended client-side protection mechanism and obtain sensitive content-notification information by listening to a device in the lock-screen state.
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Analysis
by VulDB Data Team • 06/16/2022
The vulnerability identified as CVE-2015-5892 represents a significant security flaw in Apple iOS versions prior to 9.0, specifically affecting the Siri voice assistant functionality. This issue stems from inadequate client-side protection mechanisms that fail to properly secure sensitive notification information when devices are in lock-screen mode. The vulnerability is particularly concerning because it allows attackers to bypass intended security controls through physical proximity, making it a prime example of a side-channel attack vector that exploits the trust model between user and device.
The technical flaw manifests when an attacker positions themselves in close physical proximity to a locked iOS device and listens to the device's responses to voice commands. Even though the device appears to be locked, Siri continues to process voice inputs and provide responses that may contain sensitive notification information from the device's lock screen. This occurs because the system fails to properly isolate the voice processing functionality from the notification display mechanisms during the lock-screen state. The vulnerability is categorized under CWE-200, which deals with exposure of sensitive information to an unauthorized actor, and represents a failure in information flow control within the operating system's security architecture.
From an operational perspective, this vulnerability creates a serious risk for users who may be in public spaces or shared environments where physical proximity attacks are feasible. Attackers can exploit this flaw to obtain sensitive information including calendar entries, messages, emails, and other notification content without requiring any authentication or specialized tools beyond basic proximity to the target device. The attack vector is particularly dangerous because it requires minimal technical skill and can be executed simply by having physical access to a device in lock-screen mode. This vulnerability directly impacts the principle of least privilege and demonstrates how seemingly benign features like voice assistants can become security risks when not properly isolated from sensitive data contexts.
The implications of this vulnerability extend beyond simple information disclosure, as it represents a failure in the device's security model to maintain proper separation between user interfaces and sensitive data processing. The attack can be executed without any network connectivity requirements, making it particularly stealthy and difficult to detect. This type of vulnerability is often categorized under the ATT&CK framework's technique T1552.001, which involves unsecured credentials and information exposure through physical access. Organizations and individuals should recognize that this vulnerability highlights the importance of proper access control mechanisms, particularly for features that operate in proximity-based contexts. The lack of proper input validation and output filtering during lock-screen operations creates an attack surface that can be exploited by adversaries with minimal resources and technical expertise.
Mitigation strategies for CVE-2015-5892 include upgrading to iOS 9.0 or later versions where Apple implemented proper isolation mechanisms between voice processing and notification display during lock-screen states. Users should also consider enabling additional security measures such as passcode requirements, automatic screen lock timeouts, and disabling Siri access when the device is locked. Security administrators should implement policies requiring regular operating system updates and conduct awareness training to help users understand the risks associated with leaving devices unlocked or in public spaces where physical proximity attacks may occur. The vulnerability underscores the importance of maintaining current security patches and demonstrates how seemingly minor design flaws in user interface components can create significant security risks.