CVE-2019-2135 in Android
Summary
by MITRE
In Mfc_Transceive of phNxpExtns_MifareStd.cpp, 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: Android. Versions: Android-7.0 Android-7.1.1 Android-7.1.2 Android-8.0 Android-8.1 Android-9. Android ID: A-125900276.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/01/2020
The vulnerability identified as CVE-2019-2135 resides within the Mfc_Transceive function of the phNxpExtns_MifareStd.cpp file within Android's NFC implementation. This flaw represents a classic out-of-bounds read condition that occurs when the system fails to validate array bounds before accessing memory locations. The vulnerability is classified under CWE-129 as an insufficient bounds checking issue, which directly enables unauthorized memory access patterns. The affected Android versions span from 7.0 through 9.0, indicating a substantial attack surface across multiple generations of the mobile operating system's NFC subsystem.
The technical exploitation of this vulnerability requires a specific sequence of operations involving NFC communication protocols and user interaction. An attacker must first establish a legitimate NFC connection and then trigger the Mfc_Transceive function through crafted NFC commands that manipulate the data buffer handling. The missing bounds check allows an attacker to read memory locations beyond the allocated buffer boundaries, potentially exposing sensitive data from adjacent memory regions. This information disclosure can include cryptographic keys, session tokens, or other confidential data stored in memory adjacent to the vulnerable buffer. The vulnerability does not require elevated privileges for exploitation, making it particularly concerning as it can be triggered by any NFC-enabled application.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially expose sensitive cryptographic material used in NFC transactions and secure element communications. The attack vector requires user interaction, typically through NFC handover or specific NFC tag reading operations, but once triggered, the out-of-bounds read can reveal portions of memory containing authentication credentials, encryption keys, or other sensitive operational data. This vulnerability aligns with ATT&CK technique T1059.005 for command and scripting interpreter, as it enables information gathering through memory manipulation. The exploitation process can lead to further compromise of NFC-based security mechanisms and potentially enable more sophisticated attacks against NFC-enabled devices.
Mitigation strategies for CVE-2019-2135 should focus on implementing proper bounds checking within the NFC subsystem's Mfc_Transceive function and ensuring all buffer operations validate array limits before memory access. Android security patches addressing this vulnerability typically include enhanced input validation and memory boundary checks in the NFC extension modules. Organizations should prioritize applying the latest Android security updates and consider implementing additional NFC transaction monitoring to detect anomalous behavior. The vulnerability demonstrates the critical importance of memory safety in mobile operating system components, particularly those handling cryptographic operations and secure communications. Security teams should also implement network-based monitoring to detect potential exploitation attempts through NFC traffic analysis and ensure that NFC functionality is properly configured with appropriate access controls to minimize exposure to malicious NFC interactions.