CVE-2019-9239 in Android
Summary
by MITRE
In NFC, 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-121263487
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Analysis
by VulDB Data Team • 09/12/2020
The vulnerability identified as CVE-2019-9239 resides within the Near Field Communication (NFC) subsystem 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 NFC service fails to properly validate input data boundaries before processing. The vulnerability is categorized under CWE-129 as an insufficient bounds checking flaw, which directly relates to improper input validation mechanisms. The Android ID A-121263487 further identifies this as a specific security concern within the Android security framework.
The technical flaw manifests when NFC data is received and processed without adequate boundary validation checks. An attacker can craft malicious NFC content that, when read by an affected Android device, triggers an out-of-bounds memory access. This occurs because the NFC service does not perform proper validation of the data length or structure before attempting to access memory locations. The missing bounds check allows the system to read memory beyond the allocated buffer boundaries, potentially exposing sensitive data from adjacent memory regions. This type of vulnerability falls under the ATT&CK technique T1059.007 for command and script interpreter usage, as it can be exploited through crafted NFC payloads that trigger memory corruption.
The operational impact of this vulnerability is significant despite requiring user interaction for exploitation. The attack vector necessitates that a user intentionally interacts with malicious NFC content, typically through NFC tap or scan operations. However, the low privilege requirement means that no additional execution privileges or root access are needed for exploitation. The vulnerability can lead to local information disclosure, potentially exposing sensitive data such as cryptographic keys, personal information, or other confidential data stored in memory. This makes the vulnerability particularly concerning for mobile devices where users frequently interact with NFC-enabled services and applications.
The exploitation process requires careful crafting of NFC data that specifically triggers the out-of-bounds read condition. Attackers can create malicious NFC tags or messages that, when scanned by an affected device, cause the NFC service to access memory beyond its intended boundaries. The information disclosure occurs through the accidental exposure of memory contents that may contain sensitive data from other processes or system components. This vulnerability demonstrates the importance of proper input validation in mobile operating system components, particularly those handling external data inputs like NFC communications. The issue highlights the need for comprehensive security testing of system services that process untrusted data from external sources.
Mitigation strategies for CVE-2019-9239 primarily involve applying the latest Android security patches and updates from Google, which include proper bounds checking mechanisms in the NFC service implementation. Users should ensure their devices are running the latest security updates, particularly those released after the vulnerability disclosure. Organizations should implement NFC security policies that limit NFC functionality in sensitive environments and educate users about the risks of interacting with unknown NFC tags. Additionally, network security teams should monitor for potential NFC-based attacks and consider implementing mobile device management solutions that can enforce security policies and automatic update mechanisms. The vulnerability serves as a reminder of the critical importance of input validation in mobile security and the need for continuous security testing of system services that handle external data inputs.