CVE-2019-9356 in Android
Summary
by MITRE
In NFC server, there is a possible out of bounds read due to a missing bounds check. This could lead to local information disclosure with no additional execution privileges needed. User interaction is needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-111699773
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability described in CVE-2019-9356 resides within the NFC server component of Android operating systems, specifically affecting Android 10 and earlier versions. This issue represents a classic out-of-bounds read condition that occurs when the system fails to properly validate array indices or buffer limits before accessing memory locations. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, which directly relates to the missing bounds checking mechanism that should prevent access to memory regions outside the intended buffer boundaries. The Android ID A-111699773 indicates this was tracked within Google's internal vulnerability reporting system, highlighting its significance in the mobile security landscape.
The technical flaw manifests when the NFC server processes incoming data or commands that contain malformed array indices or buffer specifications. Without proper bounds checking, the system attempts to read memory locations that may not belong to the intended data structure, potentially exposing sensitive information stored in adjacent memory regions. This type of vulnerability falls under the ATT&CK framework's T1059.001 technique for Command and Scripting Interpreter, as it can be exploited through crafted NFC communications that trigger the vulnerable code path. The out-of-bounds read operation can inadvertently reveal kernel memory contents, configuration data, or other sensitive information that should remain protected from unauthorized access.
The operational impact of this vulnerability is significant despite requiring user interaction for exploitation. An attacker must convince a user to interact with a malicious NFC device or service, but once triggered, the vulnerability can lead to local information disclosure without requiring any additional privileges beyond normal user access. This means that even a standard user account could potentially gain access to sensitive data that should only be available to system-level processes or administrators. The information disclosure could include cryptographic keys, user credentials, system configuration parameters, or other confidential data stored in memory regions accessible through the vulnerable NFC server component. The attack vector through NFC communication makes this particularly concerning for mobile environments where users frequently interact with NFC-enabled devices and services.
Mitigation strategies for CVE-2019-9356 should focus on implementing proper bounds checking mechanisms within the NFC server implementation and ensuring that all array accesses are validated against their legitimate boundaries. The recommended approach includes updating to Android 10 or later versions where this vulnerability has been patched, as well as implementing defensive programming practices such as using safe array access functions and conducting thorough input validation for all NFC-related communications. Organizations should also consider deploying NFC security monitoring solutions that can detect anomalous NFC interactions and provide alerts when potentially malicious NFC communications are detected. Additionally, users should be educated about the risks of interacting with unknown NFC devices and should be cautious when prompted to enable NFC functionality in applications or services that request access to NFC capabilities. The vulnerability demonstrates the importance of proper memory management in mobile operating systems and highlights how seemingly minor implementation flaws can lead to significant information disclosure risks in security-sensitive components like NFC servers.