CVE-2020-27031 in Android
Summary
by MITRE • 12/15/2020
In nfc_data_event of nfc_ncif.cc, there is a possible out of bounds read due to a missing bounds check. This could lead to local information disclosure with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-151313205
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-27031 resides within the NFC subsystem of Android 11 operating systems, specifically within the nfc_ncif.cc source file at the nfc_data_event function. This represents a critical out-of-bounds read condition that emerges from the absence of proper input validation mechanisms. The flaw manifests when processing NFC data events without adequate bounds checking, creating a scenario where memory access occurs beyond the allocated buffer boundaries. Such a condition typically arises when the system fails to validate the length or size of incoming NFC data packets before attempting to process them, leading to unpredictable behavior and potential security implications.
The technical nature of this vulnerability places it squarely within the CWE-129 category of "Improper Validation of Array Index" and potentially intersects with CWE-787 "Out-of-bounds Write" when considering the broader context of memory corruption vulnerabilities. The flaw operates at the system level within the NFC communication stack, where the nfc_data_event function processes incoming NFC data from external devices or internal NFC components. When malformed or oversized data packets are received, the function fails to validate the data boundaries before accessing memory locations, resulting in an out-of-bounds read operation that may expose sensitive memory contents to unauthorized access.
From an operational perspective, exploitation of this vulnerability requires an attacker to possess system execution privileges, which significantly limits the attack surface compared to user-level exploits. However, the potential impact remains severe as the vulnerability could lead to local information disclosure, potentially exposing sensitive system memory contents including cryptographic keys, authentication tokens, or other confidential data stored in memory. The fact that user interaction is not required for exploitation makes this vulnerability particularly concerning as it can be triggered automatically during NFC communication events, such as when an NFC-enabled device comes into proximity with another NFC device or when NFC functionality is actively engaged within the system. This automated exploitation capability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell and similar techniques that leverage system-level vulnerabilities without requiring user interaction.
The mitigation strategies for this vulnerability primarily involve implementing proper bounds checking mechanisms within the nfc_data_event function to validate all incoming data lengths and buffer sizes before processing. Android security patches would typically address this by adding validation checks that ensure data packet sizes remain within expected parameters, preventing memory access beyond allocated boundaries. System administrators and device manufacturers should prioritize applying the latest security updates and patches from Google to remediate this vulnerability. Additionally, network segmentation and access control measures can help limit the potential impact of such vulnerabilities by restricting NFC communication channels and reducing the attack surface. The vulnerability demonstrates the critical importance of input validation in system-level components and highlights how seemingly minor oversights in memory management can lead to significant security implications within mobile operating systems.