CVE-2012-3738 in iOS
Summary
by MITRE
The Emergency Dialer screen in the Passcode Lock implementation in Apple iOS before 6 does not properly limit the dialing methods, which allows physically proximate attackers to bypass intended access restrictions and make FaceTime calls through Voice Dialing, or obtain sensitive contact information by attempting to make a FaceTime call and reading the contact suggestions.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability described in CVE-2012-3738 represents a critical security flaw in Apple iOS versions prior to 6.0, specifically within the Passcode Lock implementation's Emergency Dialer screen. This issue stems from insufficient validation of dialing methods within the device's lock screen interface, creating a pathway for unauthorized access that bypasses intended security measures. The flaw exists in the fundamental design of how emergency calling functions interact with the passcode protection system, allowing attackers to exploit a seemingly benign feature to gain access to sensitive device functions.
The technical implementation of this vulnerability resides in the improper handling of dialing methods within the iOS lock screen environment. When a user attempts to make an emergency call through the Emergency Dialer screen, the system should enforce strict access controls to prevent unauthorized actions. However, the flaw allows attackers to manipulate the dialing process to execute FaceTime calls or access contact information without proper authentication. This occurs because the system fails to properly validate the calling method being initiated, permitting transitions from emergency calling to FaceTime functionality without requiring passcode verification. The vulnerability specifically affects the interaction between the lock screen interface and the device's telephony subsystem, where proper input validation and access control mechanisms are missing.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential data exposure and privacy breaches. Physically proximate attackers can exploit this weakness to make FaceTime calls without authentication, potentially leading to unauthorized communication sessions that could be used for surveillance or malicious activities. Additionally, the ability to read contact suggestions from FaceTime calls provides attackers with valuable information about the device user's social and professional networks. This information could be leveraged for social engineering attacks, identity theft, or targeted phishing campaigns. The vulnerability essentially transforms the emergency calling feature from a security mechanism into an attack vector, undermining the fundamental purpose of the passcode lock system.
From a cybersecurity perspective, this vulnerability aligns with CWE-668, which addresses "Exposure of Resource to Wrong Sphere," and represents a classic case of insufficient access control in a privileged context. The flaw demonstrates how seemingly harmless user interface elements can become security risks when proper validation and access control mechanisms are not implemented. The attack vector described in the CVE corresponds to ATT&CK technique T1546.001, which covers "Event Triggered Execution: Registry Run Keys / Startup Folder" but more accurately maps to privilege escalation through interface manipulation. Organizations should consider this vulnerability as part of broader mobile device security assessments, particularly in environments where physical security controls are insufficient.
Mitigation strategies for this vulnerability require immediate system updates to iOS 6.0 or later versions where Apple has implemented proper dialing method validation. System administrators should ensure all iOS devices are updated through official channels, as the patch addresses the core implementation flaw in the emergency dialer functionality. Additional protective measures include implementing mobile device management solutions that can enforce security policies and monitor for unauthorized access attempts. Security awareness training for users should emphasize the importance of keeping devices updated and being vigilant about physical security in public spaces. The vulnerability also highlights the need for comprehensive security testing of user interface elements, particularly those that provide access to sensitive functions or data, ensuring that all pathways through the system maintain proper access controls and validation mechanisms.