CVE-2019-8742 in iOS
Summary
by MITRE
The issue was addressed by restricting options offered on a locked device. This issue is fixed in iOS 13. A person with physical access to an iOS device may be able to access contacts from the lock screen.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability described in CVE-2019-8742 represents a significant security flaw in Apple's iOS operating system that persisted through multiple versions prior to iOS 13. This issue fundamentally compromised the device's lock screen security model by allowing unauthorized access to sensitive contact information through physical device access. The flaw existed in the way iOS handled contact data presentation when a device was locked, creating an unexpected information disclosure channel that bypassed normal security boundaries. This represents a classic example of inadequate access control mechanisms where the system failed to properly restrict data exposure based on device authentication state.
The technical implementation of this vulnerability stemmed from insufficient validation of user authentication status when displaying contact information on the lock screen interface. Specifically, the operating system did not properly enforce access restrictions for contact data when the device was in a locked state, allowing any individual with physical possession of the device to view contact information without proper authentication. This flaw aligns with CWE-284 Access Control issues, where improper access control mechanisms enable unauthorized access to protected resources. The vulnerability exploited the gap between the device's lock screen presentation layer and its underlying security enforcement mechanisms, creating an information leakage channel that should have been prevented by the device's authentication system.
The operational impact of CVE-2019-8742 extends beyond simple privacy concerns to encompass potential identity theft, social engineering attacks, and corporate data exposure. An attacker with physical access to an iOS device could immediately extract contact information including names, phone numbers, email addresses, and potentially other personal identifiers stored in the device's contact database. This vulnerability particularly affected enterprise environments where iOS devices might contain sensitive corporate contact information, employee directories, or customer data that could be exploited for targeted attacks. The flaw also aligns with ATT&CK technique T1083, which involves discovering system information, as it enabled unauthorized discovery of contact data that would normally be protected by device lock mechanisms.
The remediation implemented by Apple in iOS 13 addressed this vulnerability through enhanced access control restrictions on the lock screen interface. The fix specifically modified how contact information is presented when a device is locked, ensuring that sensitive data is properly restricted based on the device's authentication state. This update represents a fundamental improvement to iOS security architecture by strengthening the boundary between authenticated and unauthenticated access states. The solution demonstrates the importance of proper access control implementation and highlights how seemingly minor interface elements can create significant security vulnerabilities. Organizations should ensure all iOS devices are updated to iOS 13 or later to mitigate this risk, as the vulnerability could be exploited by anyone with physical access to a vulnerable device. The fix reinforces the principle that lock screen security should be robust and that all data presentation layers must respect authentication boundaries to prevent unauthorized information disclosure.