CVE-2016-4742 in macOS
Summary
by MITRE
NSSecureTextField in Apple OS X before 10.12 does not enable Secure Input, which allows attackers to discover credentials via a crafted app.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-4742 affects Apple macOS versions prior to 10.12, specifically targeting the NSSecureTextField component within the operating system's user interface framework. This flaw represents a significant security oversight in how the system handles sensitive input operations, particularly those involving password entry and other credential fields. The issue stems from the failure of NSSecureTextField to properly implement Secure Input mechanisms that would normally protect against malicious interference during credential entry processes. Attackers can exploit this weakness by crafting specially designed applications that monitor or intercept input events, potentially capturing sensitive information as users enter credentials into affected text fields. The vulnerability operates at the application layer of the operating system, leveraging the lack of proper input sanitization and interception protection mechanisms that should normally be present in secure credential handling components.
The technical implementation flaw resides in the NSSecureTextField class not properly engaging the Secure Input functionality that macOS provides to protect against malicious applications attempting to capture keystrokes or input events. This failure creates an attack surface where malicious software can potentially monitor input events even when users believe they are entering sensitive information into secure text fields. The vulnerability is particularly concerning because it affects the core user interface components that users interact with daily when entering passwords, PINs, or other confidential data. The absence of proper Secure Input implementation means that even legitimate applications running with elevated privileges or malicious software could potentially capture input events through various interception techniques. This weakness allows for credential harvesting through techniques that do not require direct system-level access or root privileges, making the attack vector more accessible to threat actors. The flaw aligns with CWE-200, which addresses the exposure of sensitive information, and represents a failure to properly implement security controls that should normally be present in secure input handling components.
The operational impact of CVE-2016-4742 extends beyond simple credential theft, potentially enabling attackers to conduct sophisticated credential harvesting campaigns against users of affected macOS versions. This vulnerability allows for the collection of sensitive information including passwords, account numbers, and other confidential data entered into secure text fields, which could then be used for identity theft, unauthorized access to accounts, or further exploitation within the compromised environment. The attack surface is particularly dangerous because it operates at the user interface level, meaning that even users who are cautious about running malicious applications could unknowingly expose their credentials. The vulnerability can be exploited by applications that are not necessarily malicious in nature but could be modified or compromised to include credential interception functionality. This creates a significant risk for enterprise environments where users may be running various applications that could potentially exploit this weakness. The attack vectors align with ATT&CK technique T1056.001, which involves credential injection through input capture mechanisms, and represents a failure of the operating system to properly isolate secure input contexts from potentially malicious applications.
Mitigation strategies for CVE-2016-4742 focus primarily on upgrading to macOS 10.12 or later versions where the vulnerability has been addressed through proper Secure Input implementation. System administrators should prioritize deployment of the latest macOS updates to ensure that NSSecureTextField components properly engage Secure Input mechanisms. Organizations should also implement application whitelisting policies to limit the execution of untrusted applications that could potentially exploit this vulnerability. Additional protective measures include monitoring for suspicious input interception behavior and implementing user education programs to raise awareness about the risks of running untrusted applications. Security solutions should be configured to detect and alert on potential credential interception attempts, particularly those involving text field input monitoring. The vulnerability demonstrates the importance of proper input validation and secure coding practices in user interface components, as well as the necessity of maintaining up-to-date operating system versions to protect against known security flaws. Regular security assessments should verify that Secure Input functionality is properly enabled and functioning across all affected applications and system components.