CVE-2018-9447 in Android
Summary
by MITRE • 01/18/2025
In onCreate of EmergencyCallbackModeExitDialog.java, there is a possible way to crash the emergency callback mode due to a missing null check. This could lead to local denial of service with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 02/19/2025
The vulnerability identified as CVE-2018-9447 resides within the emergency callback mode functionality of Android devices, specifically in the onCreate method of the EmergencyCallbackModeExitDialog.java component. This flaw represents a classic null pointer exception vulnerability that can be exploited to cause system instability. The issue manifests when the application fails to perform proper null validation before accessing object references, creating a scenario where the emergency callback mode can be forcibly terminated through a deliberate crash condition. The vulnerability is classified under CWE-476 which specifically addresses NULL Pointer Dereference conditions, making it a straightforward yet impactful security weakness that affects the core emergency services functionality of mobile devices.
The technical exploitation of this vulnerability occurs through a direct manipulation of the emergency callback mode exit dialog initialization process. When the onCreate method attempts to access a null object reference without proper validation, the system experiences an unhandled exception that results in the emergency callback mode crashing entirely. This crash represents a local denial of service condition because the emergency callback mode, which is critical for emergency services functionality, becomes unavailable to users. The vulnerability does not require any user interaction or additional privileges beyond normal application execution, making it particularly dangerous as it can be triggered automatically during emergency service operations. The absence of a null check in the code path means that when certain conditions are met, the application will fail to handle the null reference gracefully, leading to immediate system termination of the emergency callback service.
The operational impact of CVE-2018-9447 extends beyond simple system instability to potentially compromise emergency communication services that are critical for public safety. When the emergency callback mode crashes, users may lose access to emergency services functionality, which could be catastrophic during actual emergency situations where immediate assistance is required. This vulnerability affects the reliability and trustworthiness of emergency services on affected Android devices, as the system cannot guarantee that emergency callbacks will function properly when needed. The attack surface is particularly concerning because emergency callback mode is designed to be available and responsive at all times, yet this vulnerability creates a condition where the system can be rendered non-functional without user intervention. This aligns with ATT&CK technique T1499.004 which covers Network Denial of Service attacks, though in this case the DoS is local and affects system services rather than network connectivity.
Mitigation strategies for CVE-2018-9447 should focus on implementing proper null pointer validation within the EmergencyCallbackModeExitDialog.java component. The fix requires adding explicit null checks before any object reference is accessed during the onCreate method execution, ensuring that the application gracefully handles cases where expected objects may not be initialized. This remediation approach directly addresses the root cause identified in CWE-476 by preventing the null pointer dereference that leads to the crash condition. Device manufacturers and software vendors should prioritize this fix as part of their security update protocols, particularly for devices that rely heavily on emergency services functionality. The vulnerability also highlights the importance of comprehensive code review processes that specifically examine critical system components such as emergency callback services, ensuring that all object references are properly validated before use. Additionally, implementing proper exception handling mechanisms can provide additional protection against similar vulnerabilities in other components of the emergency services framework, aligning with defensive programming practices that reduce the attack surface for denial of service conditions.