CVE-2018-4252 in iOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.4 is affected. The issue involves the "Siri" component. It allows physically proximate attackers to bypass the lock-screen protection mechanism and obtain private notification content via Siri.
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Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2018-4252 represents a significant security flaw within Apple's iOS operating system affecting versions prior to 11.4. This issue specifically targets the Siri component of the device, which serves as the primary voice-activated assistant interface. The flaw enables attackers with physical proximity to bypass critical lock-screen protection mechanisms that are designed to safeguard user privacy and sensitive information. The vulnerability exists in the way Siri processes voice commands when a device is locked, creating an unexpected pathway for unauthorized access to private notification content.
The technical implementation of this vulnerability stems from insufficient validation and authorization checks within the Siri subsystem when processing voice inputs on locked devices. When a user speaks a command to Siri while their device is locked, the system should enforce strict security protocols to prevent access to protected content. However, the flaw allows attackers to exploit specific voice patterns or commands that can trigger Siri to display notification content without proper authentication. This represents a failure in the input validation process and demonstrates a weakness in the access control mechanisms that should prevent such unauthorized disclosure. The vulnerability is particularly concerning as it requires minimal physical proximity to exploit, making it accessible to attackers in close proximity to the target device.
The operational impact of CVE-2018-4252 extends beyond simple privacy violations, as it creates potential for more severe security breaches. Attackers can obtain sensitive information including calendar entries, messages, emails, and other private notifications that would normally be protected by the device's lock-screen security. This vulnerability directly violates the principle of least privilege and demonstrates a failure in the security model that separates user contexts and protects sensitive data. The attack vector is particularly dangerous because it does not require network access or sophisticated technical skills beyond having physical access to the device. The exploit can be executed through simple voice commands that are commonly used with Siri, making it accessible to anyone with basic knowledge of the device's voice interface. This vulnerability affects millions of iOS devices and represents a significant risk to user privacy and data protection.
Apple addressed this vulnerability in iOS 11.4 through a combination of code-level fixes and enhanced access control mechanisms within the Siri subsystem. The remediation focused on strengthening the authorization checks that occur when Siri processes voice inputs on locked devices, ensuring that all commands are properly validated before any content is displayed. Security researchers have classified this vulnerability under CWE-284, which deals with improper access control, and it aligns with ATT&CK techniques related to privilege escalation and information gathering. Organizations should prioritize updating affected iOS devices to the latest available versions to mitigate this risk, as the vulnerability remains exploitable on older iOS versions. The fix represents a critical security improvement that reinforces the fundamental security model of mobile operating systems and demonstrates the importance of continuous security testing and validation of voice-activated interfaces.