CVE-2006-1439 in Mac OS X
Summary
by MITRE
NSSecureTextField in AppKit in Apple Mac OS X 10.4.6 does not re-enable secure event input under certain circumstances, which could allow other applications in the window session to monitor input characters and keyboard events.
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Analysis
by VulDB Data Team • 07/30/2022
The vulnerability identified as CVE-2006-1439 resides within the NSSecureTextField component of AppKit in Apple Mac OS X 10.4.6, representing a critical security flaw in the operating system's input handling mechanisms. This issue fundamentally compromises the security of password and sensitive data entry fields by failing to properly manage secure input states. The vulnerability operates under the principle that when certain conditions are met during the lifecycle of a secure text field, the system does not properly restore the secure event input mode, leaving keystrokes and input characters potentially visible to other applications within the same window session. This behavior directly violates the fundamental security principle of input isolation and confidentiality that users expect from secure text fields.
The technical implementation flaw stems from improper state management within the NSSecureTextField class where the secure input mode toggle mechanism fails to correctly re-enable secure event input processing. When applications interact with secure text fields, they rely on the system to maintain a secure input context that prevents other applications from capturing keyboard events and input characters through mechanisms like event monitoring or keylogging. The failure occurs specifically under certain circumstances involving window focus changes, application switching, or specific user interaction patterns that cause the secure input state to become inconsistent. This vulnerability operates at the kernel-level interface between the application framework and the underlying security mechanisms, making it particularly dangerous as it bypasses standard application sandboxing and security boundaries. The flaw essentially creates a window of opportunity where malicious or benign applications can monitor keyboard input even when users believe they are entering sensitive information in secure fields.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential credential theft, data exfiltration, and broader system compromise. Attackers could exploit this vulnerability to capture passwords, PINs, and other sensitive information entered into secure text fields across multiple applications, potentially leading to unauthorized access to accounts, systems, and sensitive data repositories. The vulnerability affects any application that utilizes NSSecureTextField for password entry or secure data input, which includes virtually all applications requiring authentication or sensitive data handling. This creates a widespread risk across the Mac OS X ecosystem where users may unknowingly expose their credentials to other running applications. The attack surface is particularly concerning given that the vulnerability operates at the system framework level rather than application level, meaning that even legitimate applications could potentially be exploited to monitor input events, and the security implications extend to both local and network-based attacks where credential compromise could lead to further system exploitation.
Mitigation strategies for CVE-2006-1439 focus on immediate system updates and application-level protections. Apple addressed this vulnerability through subsequent security updates that corrected the state management behavior in NSSecureTextField and related AppKit components. System administrators should ensure all Mac OS X systems are updated to versions containing the patched NSSecureTextField implementation, which typically involves updating to Mac OS X 10.4.7 or later releases. Application developers should implement additional input validation and monitoring within their own applications to detect potential interference with secure input fields, though this represents a workaround rather than a complete solution. The vulnerability aligns with CWE-200, which addresses improper information exposure, and relates to ATT&CK technique T1056.001 for Input Capture through keyboard event monitoring. Organizations should consider implementing additional security monitoring to detect potential exploitation attempts, particularly in environments where sensitive data handling is prevalent. The vulnerability also highlights the importance of proper state management in security-critical components and demonstrates how seemingly minor implementation flaws in system frameworks can have significant security implications across the entire operating system ecosystem.